Q.I have very large hives that appear in long lines all over my body. They are extremely itchy and can appear at any time with no provocation whatsoever. When I go to bed at night I get them in crisscrosses all over my body. Is there anything I can do to stop the itching or prevent it altogether? Thank you.

A.When you rub your skin or scratch, do you get a red "welt" area? This response is actually very common. Basically, it is a skin oversensitivity phenomenon called dermatographism. This is very similar to hives. There is a cell in the skin called a mast cell. This cell contains histamine. When the cell is "over-excited" or stimulated, it releases histamine in the skin. Many times antihistamines will control the problem. These are available now over-the-counter. Most of the time this will resolve on its own.

Q.Since early teens, I have experienced and 'exercise induced' rash with almost unbearable itching. The rash itself is unremarkable however the areas affected (generally the legs have an overall redness about them when affected. The rash occurs whether I am walking or even swimming, occurring more rapidly often in cold weather than warm. In warm weather, a walk of even half a mile will generally be enough to start the itch. Can you possibly advise your thoughts on this?

A.Exercise induced rashes may be suggestive of hives. Hives can be from a number of causes. A cell in the skin, called a mast cell, releases a chemical called histamine which produces welts and itching. Treatment is symptomatic; however, many people pre medicate themselves with antihistamines prior to an activity that causes hives. Read about Hives on for suggestions on maintenance.

Q.I am nine months pregnant and recently developed hives. My question is: Does pregnancy sometimes cause hives to develop? If so, why?

A. Hives during pregnancy are not unusual. The medical term is pruritic urticarial papules and plaques of pregnancy. Essentially, the flux of hormones and daily changes of pregnancy stimulate a histamine release in the skin. This is especially prominent during the last trimester of pregnancy. The skin eruption consists of firm pink to red plaques, sometimes vesicles, starting in the stretch marks and extending to the abdomen, thighs, buttocks and arms. Rarely is the upper chest involved. There is no risk to the pregnancy. Antihistamines are used to treat this but this should first be cleared with your OB/GYN. Topical anti-itch lotions are very comforting, especially if they are refrigerated. The hives usually resolve within the first two weeks after delivery

Q.I have very fair skin, so during the summer I like to use a self-tanning product. I have starting getting hives from these products. Do you know what is likely causing the reaction and is there a new brand I should try?

A.Hives are caused by the release of a chemical called histamine in the skin. When there is a clear association with a skin product, this can be considered an allergic reaction. Skin products contain many ingredients. The active ingredient in self-tanners is dihydroxyacetone (DHA). You will have to try different self-tanners and see which ones are irritating.

Q.My son has suffered from AQUAGENIC URTICARIA for fifteen years since his teens. It is a tormenting disease and antihistamines seem to help little. Is there a cure, or best, is there a cause so we can rid him of this horrible problem?

A.Aquagenic urticaria is hives from water exposure. There is a histamine release in the skin from water of any temperature. This type of urticaria is thought to have an immunological basis. The cause is unclear and the treatment varies from person to person. When antihistamines are ineffective, other medications such as calcium channel blockers or immunosuppressants can be used. This is a rare condition and you need to find a physician in your area that will work with you and try different medications as needed