Antihistamines



Antihistamines are drugs that can be used to alleviate the effects of histamine found in the blood. Histamine is the natural chemical which is produced by the immune system of the human body. The release of histamnes stimlates an increased blood flow to the area affetced. It causes the swelling of the mucous membranes lining in the nose and throat due to the flow of the fluid out of the blood vessels and stimulates the gland situated nearby to produce mucus. The symptoms such as itching, swelling or reddening is caused by histamine. It can also cause itchy eyes, running nose, watery eyes, sneezing and can even result in breathing difficulties.

The most important action of histamines is associated with allergies. Histamine is released as soon as the body comes into contact with an allergen, a substance which is not usually harmful, like pollen, but that may cause overreaction by the immune system of humans in some. The other functions of histamines in the body are tightening and widening of blood vessels as well as the squeezing of muscles in the respiratory system and digestive system.

Antihistamines are used to prevent the histamine from performing the overreactions. They are commonly used to treat allergic reactions. Some types are also used for treating conditions like stomach ulcers, travel sickness and migrane.

They can be availed as tablets, injection and creams. The earlier antihistamines tent to result in sedation, rarely, the heart arrhythmias. The antihistamines available now are non-sedating and have a longer effect, so that the dosage can be reduced.

The antihistamine creams are used to treating insect bites. The oral antihistamines for hay fever and antihistamine creams are available over-the-counter.

Usage

Antihistamines are commonly used in the treatment of allergies like hay fever and insect bites.
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They help in the reduction of itching of eyes and nose, runny nose as well as sneezing and watering eyes. They can be used in combination with decongestants as treatment for nasal congestion.

Oral antihistamines can also be used for allergies to some medicines, in preventing and treating migraine symptoms, and in relieving severe cases of morning sickness.
Topical antihistamines include ointments and creams that are applied to the skin. Both the antihistamine tablets and creams are effective in the reduction of urticaria, white itchy bumps on skin due to insect bites and stings. Oral antihistamines are also used to treat chronic (long-lasting) urticaria.

Eye drops with antihistamines may be applied to the eyes for allergic conjunctivitis. Antihistamine injections are used after adrenaline injections to avoid serious allergic reactions like anaphylactic shock.

Side effects

The major side effect of using older antihistamines is sedation Other side effects includes blurred vision, headache and dry mouth.

Antihistamine creams may result in hypersensitivity of skin, So use of topical antihistamines should be avoided to skin with eczema.

Even though new generations do not have sedating effects, one must wait to know the reactions. So avoid driving during such medication.

Terfenadine which is used for hay fever treatment even causes your heart beat faster as well as in an irregular way.

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