Non sedating antihistamines definition

Sedating antihistamines oppose the effects of histamine on H1 receptors in your brain, which is why they cause sedation and drowsiness.Antihistamines are very good at relieving symptoms of an allergic reaction, such as: First-generation antihistamines were developed more than seventy years ago and are still in widespread use today.They are used primarily to treat disorders where abnormal or excessive histamine release by inflammatory cells is thought to underly illness.This includes conditions such as: Other conditions such as hyper-reactive (vasomotor) rhinitis and pruritus of any cause are commonly treated with antihistamines, although there is little evidence that histamine plays a contributory role.

This term is used to describe drugs that antagonise histamine H1 receptors.

Stimulation of these receptors can lead to conditions such as a skin rash or inflammation, a narrowing of the airways (bronchoconstriction), hay fever, or motion sickness.

Histamine-1 receptors are also found in the brain and spinal cord, and stimulation of these receptors makes you more awake and alert.

They act on histamine-1 receptors in the periphery and are unlikely to penetrate the brain, so are less likely to cause side effects or interact with drugs.

Most second-generation antihistamines do not cause drowsiness, although some (such as cetirizine and fexofenadine), may be more likely to do so at higher dosages.

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