It is in all likelihood an allergy. The usual associated symptoms are itching and occasional pain. The major causes of hives or urticaria are;
1) Foods or food additives
2) Inhalation, ingestion of, or contact with antigens
3) Drug reactions
4) Infections: bacterial, fungal, viral, and helminthic/parasites
5) Insects (papular urticaria)
6) Cold urticaria
7) Aquagenic (water) urticaria
8) Solar (Sun) urticaria
9) Chronic autoimmune (problems of immunity) urticaria
10) Chronic idiopathic (unknown reason) urticaria
So it is a sort of detective work to find the cause.
A chronic urticaria is treated as following;
1) A consultation with an allergist, if not yet done.
2) Avoid foods with known food allergies.
3) Avoidance of mental stress over tiredness, alcohol, nonsteroidal anti-inflammatory drugs, and tight-fitting garments.
4) Psychologic stress can trigger or increase itching, so taking care of those factors.
5) Night time symptoms are helped by lukewarm bathing and keeping the temperature of the bedroom slightly low.
6) Itching is significantly helped by menthol and phenol cream.
7) Non sedating antihistamines.
8) Hydroxyzine or doxepin in night time.
9) Colchicine or dapsone is given who do not respond to above.
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