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Urticaria is a common itchy skin rash which is also known as hives or wheals. The rash consists of red swollen patches of varying sizes on the skin resembling mosquito-bite reaction. The rash usually lasts for several hours before fading away. Sometimes, it can involve the soft tissue around the eyes or lips causing swelling. This is called angio-oedema.
Urticaria arises as a result of a substance called “histamine’ which is released from mast cells, a special type of immune cells in the skin. Histamine is released normally in allergic reactions or insect bite reactions. In urticaria, a trigger causes release of large amounts of histamine. Histamine causes the blood vessels in the skin to dilate and become leaky leading to accumulation of fluid in the tissues and swelling of the skin.
Individual hives in typical urticaria usually lasts less than a day, but new hives will appear on other areas. The whole episode of urticaria can last less than 6 weeks (acute urticaria) or more than 6 weeks (chronic urticaria).
Causes of acute urticaria include viral infections, drug allergies or reactions, insect bite or stings and food allergies. Very often, the cause of acute urticaria may not be apparent and none may be found.
Patients who have the chronic form of urticaria often have spontaneous urticaria in which no cause can be identified. Some of these cases may be autoimmune in nature. Physical factors/ stimulus can also cause chronic urticaria. When this happens, it is called physical urticaria. Examples of physical factors/ stimuli are physical pressure on the skin, exercise, cold/ hot temperature and sunlight.
If you see a doctor, the doctor will try to identify the cause of your urticaria by taking a detailed history. Sometimes, blood tests may be done to exclude underlying ill health or other associated conditions. The mainstay of treatment for urticaria is oral anti-histamines. These medications are used to suppress the effect of histamine.
It is also important to avoid any known triggers/ stimuli which cause or aggravate the urticaria. Generally, it is advisable to avoid alcohol and stay in a cool environment.
Some antihistamines may cause drowsiness. However, there are non-sedative antihistamines the doctor can prescribe if you experience drowsiness. Some antihistamines can also cause dry eyes and mouth in sensitive individuals. However, most antihistamines are very safe, even when taken for prolonged periods.
There are certain antihistamines which are safer in pregnancy, so it is important to discuss with your doctor what antihistamines to take if you are pregnant.