Different kinds of urticaria

• Heat rash. Heat can bring urticaria out, or make it worse.

• Chronic 'idiopathic' urticaria. By far the commonest form of urticaria which lasts a long time. A puzzling name for a puzzling condition.

• Cold Urticaria. If cold brings out your hives, take great care to avoid falling in the water, and see a specialist.

• Pressure Urticaria. There are at least two completely different kinds of urticaria brought on by pressure on the skin.

• Cholinergic urticaria. Tiny hives when you get hot.

• Sunlight can cause urticaria: Solar urticaria. Hives caused only by direct sunlight, a rather rare condition. The much more common 'polymorphous light eruption' can be mislabelled as solar urticaria.

• Urticaria caused by water. Aquagenic urticaria.

• Vasculitic urticaria, urticarial vasculitis.

• Contact urticaria. Hives from allergy to things touching the skin.

• Urticaria caused by aspirin, and by food colouring and preservatives, and salicylates.
  The commonest discoverable cause of chronic urticaria which you can do something about. The dietitian may make tablets unnecessary, but aspirin and some other painkillers could be dangerous.

• Can urticaria be caused by stress?

• Other kinds of urticaria

Other websites on urticaria

If you have a lumpy and itchy rash which looks like the effect of a nettle sting and occurs for more than six weeks, you are like the one person in five who gets this at some stage of life. We call this a 'nettlerash' even though it is not caused by nettles. The Latin name urticaria means exactly the same thing, because it comes from the Latin word 'urtica', which means stinging nettle. The English word 'hives' has the merit that it does not suggest the rash is caused by nettles.

Photograph of severe urticaria at the front of the elbow. The weals or hives are large, and have run into each other. There is no peeling or flaking of the skin at all, and the skin will look completely normal apart from any effect from scratching when the hives disappear. The hives are very itchy. Click here for more detailed picture (100K, 30 sec at 28.2 kbps).

You may not be sure whether you have blisters, or hives (weals). A blister is the sort of thing you might get after a burn or after rowing or heavy work with a spade; it is a little sac filled with clear liquid, which may break so that the liquid comes out and the sac becomes flat, with a loose membrane lying on the skin surface. A weal is also raised above the surface, but does not have a loose membrane over liquid which can run out. Here is a diagram to help you, though the colours are not realistic because of the limits of the Internet.

Diagram to show the difference between weals (hives) and blisters. The colours are not at all accurate because of limitations of Internet browsers, and the shape and size of weals can vary a lot.

If you do really have a rash with true blisters, you really must see a skin specialist. A rash with true blisters is not urticaria, with which the rest of this page is concerned.

Urticaria on the hands looks different. This is because the skin is so tightly bound down that it is simply not loose enough to form ordinary weals. Instead you get tiny very itchy pimples, especially on the sides of the fingers. This is called cheiropomphylix, a pompous word if ever there was one. But really it's just hives of the fingers.

People often say that someone with urticaria has 'an allergy'. This may well be true if the urticaria comes on just for a matter of days after a food or medicine which often causes allergic reactions, but is rarely if ever true of urticaria which lasts for months.

In England, people often call hives or urticaria a 'heat rash' because in some people urticaria seems to appear only in hot conditions. This expression is confusing in others, and I don't find it helpful. Wrongly, a lot of people refer to urticaria as 'prickly heat'. This really is nonsense. True 'prickly heat' is an entirely different problem caused in the tropics by infection in the sweat glands of people with bad skin hygiene who don't shower enough. It is not urticaria.

Some people who get urticaria also get much larger swellings as part and parcel of the same condition. This is ANGIOEDEMA (ANGIEDEMA). The swellings come and go, often affecting your lips, eyelids, other parts of your mouth or throat, and other parts of the body. Click here for more information about angioedema.  

Acute Urticaria

Many people get urticaria when they eat shrimps or strawberries or in hot weather. In fact they call it a 'strawberry rash' or a 'heat rash'. This usually lasts just a short time, hours or a few days. This is called 'acute urticaria'. The word 'acute' means that it lasts just a short time.

Acute urticaria can also be caused by other foods or by medicines, especially aspirin and some other painkillers. In this case it is usually obvious what is causing it, and the cause may be easy to avoid. However, aspirin-sensitive urticaria can also be caused by foods containing salicylates, some food colourings, and some food preservatives. This may not be obvious to you. If this seems possible, I would recommend the help of a dietitian to sort this out.

Acute urticaria can also be one of the features of a much more serious food allergy. This happens with allergy to nuts, for example, or with allergy to rubber latex, which goes with allergy to bananas and other fruits. In fact acute urticaria is also one of the symptoms of a serious kind of allergic reaction affecting the whole body, called anaphylaxis, which may be life-threatening.

Chronic Urticaria

If urticaria lasts six weeks or more, it is called 'chronic urticaria'. The word 'chronic' simply means that it lasts a long time.

But how long is long? In a survey, it lasted a year or more in more than 50% of sufferers and 20 years or more in 20% of them. Of course this does mean that in almost half the people it clears up within a year and in 80% it clears up within 20 years or less (Champion and others, British Journal of Dermatology 1969). So don't count on it clearing up next week (though it may), and get it treated properly.

Chronic urticaria is hardly ever caused by true allergy. In fact we usually can't find the cause, and this regrettable fact causes patients and doctors a vast deal of frustration. In recent years, top researchers have found that quite a lot of people with chronic urticaria have antibodies in their blood which seem to explain the urticaria. But the test for this is too complicated to be used except for research, and the results do not seem to make any difference to the outlook or the choice of treatment. Neither do we know why some people with urticaria make these antibodies.

The rest of this page is about chronic urticaria.

Heat rash

Almost all urticaria (perhaps all) urticaria gets worse if the skin is warm. You may notice this if you have a hot bath or shower, or if the weather is hot.

Mistakenly, some people describe this as 'prickly heat'. But prickly heat is completely different. It is an infection of the sweat glands which some people get if they live in the tropics and do not shower.

Some people get urticaria only on hot days. Many people call this a 'heat rash'. It is probably mostly ordinary urticaria which is just not bad enough to show up on its own but needs the extra factor of heat to make it show up.

Urticaria in which the lumps are especially tiny, appearing all over the body when you get hot, especially when exercising, could mean it is 'cholinergic urticaria''.

Chronic 'idiopathic' urticaria: by far the commonest type.
(Long-lasting urticaria with no known cause)

The word 'idiopathic' is a ridiculous word used by doctors to mean that they don't know the cause of something. It means 'self-causing', which is obvious nonsense. But we're stuck with the word because all doctors use it. There is a better word, even if you prefer Latin or Greek words to English ones; it is 'cryptogenic', which means 'hidden cause'. Nobody uses this more sensible word for urticaria with no currently discoverable cause.

Of course there has to be a cause. Every sensible doctor will agree that removing the cause would be the best treatment if only we knew what the cause was, and if only we could remove it without doing you more harm than the urticaria causes. Every patient would rather remove the cause than take treatment all the time.

But most people with chronic (lasting more than six weeks) urticaria have no cause found, no matter how hard everyone tries.

This frustrates everybody no end. Chronic urticaria is no joke, and the itching makes people thoroughly miserable, and for good reasons. But if you are the sort of person who won't accept that the doctor can't do anything else to find a cause, then you and the doctor are going to have a difficult time. More difficult than just having the illness alone.

It's not that your doctor does not care. It is that there are limits to medical science. Perhaps you could help by making your contribution to research, for example by volunteering to help with research tests, or by collecting or donating money for research on urticaria.

There is an idea about the way some chronic urticaria comes about. Research workers in London have found that a few patients have antibodies to their own 'allergy-producing antibodies', i.e. antibodies to their own antibodies. Others, far more numerous, have antibodies to molecules on the surface of the histamine-producing cells (mast cells). In either case the result is that these cells release histamine (and other chemicals) into the skin. Histamine in the skin produces urticaria, though evidently it is not the only substance which can do so. This discovery seems to apply to quite a lot of patients in a clinic so specialised that other experts send their especially puzzling urticaria patients there. Whether it applies just as often among all urticaria patients is something which remains to be found out, as far as I know.

Unfortunately this discovery makes no difference to treatment, even for those people who have these antibodies. There are treatments which can be used to remove the antibodies or to interfere with this mechanism, but at the moment these have too many disadvantages to be worth using except for research.

So mostly the treatment is just the same as for most kinds of urticaria, and relies mainly on antihistamine tablets.

You can also avoid aggravating factors. Almost certainly hot conditions will make you worse, and cool conditions will make you better. So, for example, using a minimum of bedclothes, so that you are no warmer than necessary, will help quite a lot of people.

The good news is that the treatment usually works, or can be made to work by skilled choice of medicines. But there are a very few sufferers for whom the usual specialist treatments do not work. They need to find a specialist, usually a dermatologist, who takes a special interest in urticaria.

The other good news is that sooner or later the urticaria nearly always clears up. But this may happen in weeks or after decades, and is totally unpredictable.

Doctors often treat severe urticaria which does not respond to the usual treatment with 'steroid tablets'. This makes sense in the short run if the urticaria is really getting you down, or is going to interfere with something important you have to do, like an important interview or dealing with an especially stressful situation. But in the long run the steroid tablets would have serious side effects, so they must be stopped. When they are stopped, the urticaria usually comes back.

'Steroid creams' usually don't work for urticaria.

Cold Urticaria

One value of the 'ice cube test' is that you can use it to check whether your treatment is working. It is pretty easy to do this test for yourself at home in a standard way, with and without the treatment. Check with your doctor or specialist how to do the test. In a few people the ice cube test does not work, though they get into terrible trouble when they immerse themselves in cold water.

Suggestions about the ice cube test: wrap an ordinary ice cube from the freezer in a thin plastic bag. Fold a kitchen towel to form an insulating pad through which you can hold the ice cube, in its bag, in one hand. Apply the ice cube to the middle of your other forearm, on the same side of your forearm as the palm of your hand. Hold in place firmly for 1, 3 or 5 minutes (try each of these in succession until you get a result or have tried them all). When you remove the ice cube there will be a pale patch of skin where the ice was. If you get slight but very definite swelling over the next 3 to 5 minutes, as the skin warms up again, this is a positive result.
N.B.: a specialist will know more than this.

Usually we don't know why people get cold urticaria, though it is very clear that it is not all one disease; there are quite a few variant forms. Your specialist may do some blood tests for things called cryoglobulins, cryofibrinogen, cold agglutinins and other things, but in our experience these are most unlikely to be abnormal. However, occasionally they are, and quite a number of underlying illnesses can cause cold urticaria. This is an area for a specialist. So one reason why it is useful to know if you have cold urticaria is that you probably should see a specialist, even though the outcome is likely to be reassuring to you. If you have any other symptoms of illness as well as cold urticaria, then a specialist consultation may be important. Your family doctor will be able to help you decide.

It is important to know if you have cold urticaria, particularly if you take part in water sports. If you fall in the water, the sudden cooling of all of your skin (even in the tropics!) is dangerous. This is because cold urticaria all over your body at once can make your blood pressure drop because so much fluid comes out of your blood vessels to make the swellings. You may become unconscious, with a risk of drowning. If you have cold urticaria, take extra care not to fall in the water or to make sure you can be fished out promptly and easily (e.g. if yachting, clip on a safety harness even in circumstances when others would not). Take a full dose of a good antihistamine beforehand. Wearing a wet suit or dry suit even when you otherwise would not will provide considerable protection. And of course an efficient life jacket is more important for you than for others.

Antihistamines often don't work so well in cold urticaria, although we still recommend them. However, modern low-sedating antihistamines cetirizine (Zyrtec, Zirtec) and loratadine (Clarityn) worked just as well as some older antihistamines which have a reputation in this condition but make you drowsy. The new antihistamines terfenadine (Allegra, Telfast) and desloratadine (Neoclarityn) should also turn out to be good.

Information for doctors: Villas Martinez F, Contreras FJ, Lopez Cazana JM, & others: A comparison of new nonsedating and classical antihistamines in the treatment of primary acquired cold urticaria (ACU). J Investig Allergol Clin Immunol. 1992;2:258-62.

People have tried other treatments.
Information for doctors: One group (Husz S, Toth-Kasa I, Kiss M, Dobozy A. Treatment of cold urticaria. Int J Dermatol. 1994;33:210-3.) found tablets normally used for asthma (terbutaline and aminophylline) helpful. Theophylline is essentially the same drug as aminophylline, but less likely to cause rashes.

It may be possible to 'desensitise' yourself against cold exposure by starting with a form of washing which you know does not harm you, and repeating this, slowly increasing your exposure to cold. You must get advice from a specialist about this before trying it, as people with cold urticaria are so different from each other. Done badly, it could be dangerous in some people.

25% of people with cold urticaria lose the problem within about 1 to 2 years, but 20% continue to have it for more than 10 years (Habif, Clinical Dermatology, 3rd ed.). These are global figures; they will obviously differ between different forms of cold urticaria. Unfortunately, some people may never lose the cold urticaria.

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Pressure Urticaria

A generally more serious form of urticaria produced by pressure is delayed pressure urticaria. It may also appear under bra straps and belts, and may be a problem in people who carry heavy items over the shoulder, or in the feet of people who have to stand a lot. This typically comes on some hours after sustained pressure on the skin, but the time ranges from 30 minutes to 9 hours after pressure. Although this is called urticaria, the appearance is typically quite different from ordinary urticaria. It is a more diffuse swelling, and not really a typical weal or hive. The microscopic changes in the skin are also different from those in common urticaria.

Unfortunately delayed pressure urticaria is difficult to treat. Antihistamines are usually a big disappointment, and people have generally found that the only successful treatments are steroid tablets at quite high doses (e.g. prednisolone or prednisone 30 mg daily), or avoiding the pressure. Steroid tablets at these doses do have important side effects, so doctors will be reluctant to use them for more than short periods. Avoiding pressure may mean changing jobs for people who encounter the problem at work. There is an isolated report (Engler RJ; Squire E; Benson P. Chronic sulfasalazine therapy in the treatment of delayed pressure urticaria and angioedema.. Ann Allergy Asthma Immunol. 1995; 74: 155-9) claiming that a drug called sulphasalazine helped two patients, but this is a drug with enough potential for side effects to merit careful consideration by a specialist before it should be prescribed for you. The absence of other reports of benefit since 1995 makes me wonder whether this treatment works for many people. I have tried it without success. The condition is sufficiently distressing in many of the people who have it, and is a sufficient area of interest to skin specialists, for new ideas to be tried pretty quickly.

A skin specialist will have more detailed knowledge about pressure urticaria, and we definitely recommend that you should see one if you have delayed pressure urticaria or if your urticaria does not go away after your usual doctor has tried all the treatments he or she can think of.

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Cholinergic urticaria

Tiny lumps (2 to 4 mm diameter) all over appearing when the body gets hot, especially when exercising, are typical of 'cholinergic urticaria'.

The word 'cholinergic' was used because the rash can also be produced in some people by injections of a chemical released by nerves and called acetylcholine. It is not clear that this is the way the rash comes about in people who have cholinergic urticaria.

Cholinergic urticaria is difficult to treat, so seeing a specialist may be well worthwhile.

Sunlight can cause urticaria. Solar urticaria

All urticaria is made worse by heat. But if you get true urticaria only when sunlight has been shining on your skin, you may have solar urticaria. This is rather rare, and people often confuse it with a much more common rash called polymorphous light eruption (polymorphic light eruption). If you have solar urticaria, you get weals in minutes and they last for less than an hour. But if you have polymorphous light eruption the rash takes hours to appear, takes days to disappear, only rarely looks like real urticaria (though it can have a number of different appearances), and needs different treatment. There are other kinds of skin problem which can be caused by sunlight, and a skin specialist will be expert on these. Some skin specialists take a special interest in rashes caused by light.

There are different kinds of solar urticaria, and your specialist may want to do some blood and urine tests. The effectiveness and choice of sunscreen creams depends on which kind of solar urticaria you have, and some people may need sunscreen creams with titanium oxide or zinc oxide. Some people will not get it if they are behind glass, but others will. The effect of antihistamines varies a lot.

Urticaria caused by water. Aquagenic urticaria.

Some people get urticaria when their skin comes into contact with water, whether it is hot, cold or anything in between. Antihistamines before contact with water or taken regularly are the standard treatment.

Vasculitic urticaria, urticarial vasculitis, hypocomplementemic urticaria (hypocomplementaemic urticaria)

Some people with vasculitic urticaria have an abnormal blood test result showing that something called 'complement' is present in lower amounts than normal. The urticaria is then called hypocomplementemic (hypocomplementaemic) urticaria . As far as I am currently aware, the significance is much the same as in vasculitic urticaria generally, but it would certainly make your doctor want to test you for autoimmune diseases, particularly systemic lupus erythematosus (SLE), usually with the result that you turn out not to have this. The word autoimmune means that the immune system of the body, which is mainly meant to defend us against invaders such as bacteria and viruses, is reacting against the body itself. Autoimmune reactions are common, particularly later in life, and do not necessarily make you ill. Rheumatoid arthritis is a common example of an illness caused by autoimmune reactions, but there is quite a variety of such illnesses.

SLE is a moderately common autoimmune condition and ranges in severity from trivial to life-threatening. It has its own range of treatments, which are highly effective if used promptly and with appropriate long-term vigilance by a specialist, but which in all but the mildest cases do involve a risk of side effects which you would definitely want to discuss with the doctor.

Complement is a collection of protein substances in the blood plasma involved in the removal of foreign substances. The complement proteins which we normally have in our blood help to remove bacteria, viruses and other micro-organisms from our bodies. They also help the removal of the body's own proteins when these have become bound to antibodies, something which does happen and in fact is important for health. Usually we do not understand why they can be low in some vasculitic urticaria. When complement is at work it can also mimic some allergic reactions because it can trigger cells in your body to release substances such as histamine, which can bring about allergy-like symptoms including urticaria.

Your specialist may well remove a small piece of skin (take a skin biopsy) to have it looked at under the microscope. This is often the best way of knowing whether you have vasculitic urticaria.

Treatment is more difficult than for ordinary urticaria, and usually needs quite different medicines.

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Contact Urticaria

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Urticaria caused by aspirin, and by food colouring and preservatives, and salicylates.

Some people get urticaria or angioedema. or both if they take aspirin or painkillers such as ibuprofen (e.g. Nurofen in the UK) called 'NSAIDs'. This abbreviation stands for 'Non-Steroidal Anti-Inflammatory Drugs', but a wit wrote that it stood for 'New Sorts of Aspirin In Disguise'. Reactions can endanger life, and the fact that a remedy contains aspirin or a similar drug may not be obvious at all. For example in the UK Beecham's powders and Alka Selzer both contain full doses of aspirin. If you have this condition, consult a specialist, and do not take any painkiller or similar remedy without checking with a doctor or qualified pharmacist that it is all right for people with aspirin hypersensitivity. Reactions are also caused by amidopyrine, a painkiller banned in the USA and UK but used in many other countries under many trade names. Paracetamol is usually all right for people who are hypersensitive to aspirin, and if it does cause reactions in them, they are always much milder. Also all right are the codeine family of painkilers, codeine phosphate, dihydrocodeine and dextropopoxyphene. HOWEVER, DO NOTE THE DISCLAIMER AT ON THE HOME PAGE OF THIS WEBSITE, AND NOTE THAT NOTHING IN THIS WEBSITE IS INTENDED OR CAN BE REGARDED AS INDIVIDUAL MEDICAL ADVICE. IRRESPECTIVE OF WHAT YOU READ IN THIS SITE, YOUR MEDICAL TREATMENT SHOULD FOLLOW THE RECOMMENDATIONS OF YOUR OWN DOCTOR, WHO SEES YOU IN PERSON.

Some people with chronic or recurring urticaria (or angioedema.) get complete relief if they avoid food and drink (and medicines) containing substances called salicylates, which are present in some plant foods, and if they also avoid foods containing some artificial colouring (azo dyes) or preservatives (benzoates). The effect is dramatic and makes antihistamines unnecessary in these people. SUCH PEOPLE ARE ALSO HYPERSENSITIVE TO ASPIRIN AND NSAIDs, WHICH MAY BE DANGEROUS IN THIS CONDITION. Often they have not used aspirin as such, and people may come to the wrong conclusion that because of this aspirin cannot be the cause. If you have this problem, you need to see a dietitian. Although some doctors hand out a diet sheet for this, dietitians get better results.

In my own experience this cause of urticaria is by far the commonest discoverable cause of chronic urticaria which you can do something about, even though this applies in only a minority of people with chronic urticaria. Moreover, the benefits of discovering this cause are that you should be able to do without medication except when you eat the offending foods, and that it is important to know that you must not have aspirin or NSAIDs.

There is no blood test or skin test for aspirin hypersensitivity. Avoidance and consumption are the only known ways of diagnosing it. IF YOU THINK YOU MAY BE HYPERSENSITIVE TO ASPIRIN IT COULD BE EXTREMELY DANGEROUS TO TEST YOURSELF BY TAKING ASPIRIN. RELY ON A DOCTOR WITH SUITABLE EXPERTISE TO HELP YOU GET A DIAGNOSIS.

Experts are not agreed about whether aspirin and related substances are the fundamental cause of this urticaria, or whether some people who have urticaria for another reason (usually unknown) have it worsened or made apparent by aspirin. For practical purposes the consequences are the same, and it is valid to refer to aspirin as a cause of such urticaria, even if it is not the sole cause.

We do not understand why aspirin and the other substances mentioned here cause urticaria. There is good evidence that it has little or nothing to do with common allergies such as hay fever, asthma, allergy to pets, and common food allergies.

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Other kinds of urticaria

There are other recognised kinds of urticaria. It is unlikely that we will ever deal with all of them on this page.

Treatment of urticaria

• Antihistamines (H1 blockers)

  Antihistamines are the mainstay of treatment, and most patients need no other treatment. It is very important that you should have an antihistamine which is appropriate for you. We are talking here about the sort of antihistamine usually used for allergies, even though chronic urticaria is rarely if ever caused by true allergies. This type of antihistamine is called an 'H1 blocker'. These commonly used antihistamines are two main kinds.

  • Older H1 blocker antihistamines, which make you sleepy

  • Newer H1 antihistamines, which cause little nor no sleepiness

  Actually this is an oversimplification; the real difference is even more serious. The older antihistamines affect driving safety even when they don't make you feel noticeably sleepy. They also affect learning by schoolchildren.

  However, this same sedative effect of the older antihistamines means they help better against itchiness at night.

  Whether your doctor chooses the older or the newer type is an important matter; it needs to be the best one for your particular needs.

  Click here to find out more about antihistamine tablets, capsules, or liquid medicines

• Antihistamines which are usually used for stomach or duodenal ulcers (H2 blockers)

  Some clinical trials showed that taking a different kind of antihistamine called an 'H2 blocker' as well as one of the H1 blockers increased the success rate of treatment slightly. But a view is growing that they contribute little help for urticaria in practice, and I share that view. H2 blockers are mainly used for ulcers and inflammation in the gullet, stomach and duodenum. You should not take them if an H1 blocker gives you adequate relief. If you do try them and they do not cause an obvious improvement, ask your doctor whether it would be better for you to stop taking them.

• Other medicines

  These are mostly the province of specialists. If the ordinary treatments don't work well enough, you should surely see a specialist. The point is that alternatives do exist. In the difficult situation in which antihistamines don't help chronic urticaria, doctors often resort to prescribing steroid tablets such as prednisone or prednisolone. It is definitely worth seeing a good specialist if you are facing long-term treatment with these steroids, because there is a view that other treatments are preferable and that long-term steroid tablets are rarely necessary. Recent book chapters and articles by M. Greaves and A. Kobza-Black cover this point.

Other websites on urticaria

Look first at the excellent site of the International Chronic Urticaria Society (ICUS) who provide a gargantuan list of other urticaria sites in addition to good information. The section on different kinds of urticaria is written very well as regards factual content, but frequently uses professional jargon in places where it should use plain English. It is referenced; in other words it gives sources for its opinions, which the AAIR site does not. This is a definite point in favour of the ICUS site. It has a section on 'alternative' approaches to treatment which does warn you that they do not endorse these, and I suppose they have included it in the interests of freedom of expression and a democratic approach. I do not endorse such approaches at all. Stick to their mainstream section.

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