Antihistamine drugs antagonise the action of HISTAMINE and are therefore of value in the treatment of certain allergic conditions (see ALLERGY). They may be divided into those with a central action (e.g. ?upheniramine and cyclizine) and those such as loratidine and terfenadine with almost no central action. Antihistamines are also of some value in the treatment of vasomotor RHINITIS (see also under NOSE, DISORDERS OF); they reduce rhinorrhoea and sneezing but are usually less e?ective in relieving nasal congestion. All antihistamines are useful in the treatment of URTICARIA and certain allergic skin rashes, insect bites and stings, as well as in the treatment of drug allergies. Chlorpheniramine or promethazine injections are useful in the emergency treatment of angio-oedema (see under URTICARIA) and ANAPHYLAXIS.
There is little evidence that any one antihistamine is superior to another, and patients vary considerably in their response to them. The antihistamines di?er in their duration of action and in the incidence of side-effects such as drowsiness. Most are short-acting, but some (such as promethazine) work for up to 12 hours. They all cause sedation but promethazine, trimeprazine and dimenhydrinate tend to be more sedating while chlorpheniramine and cyclizine are less so, as are astemizole, oxatomide and terfenadine. Patients should be warned that their ability to drive or operate machinery may be impaired when taking these drugs, and that the effects of ALCOHOL may be increased.... antihistamine drugs
A characteristic set of symptoms experienced by many people when subjected to the constant changes of position caused, for example, by the pitching and rolling motion of a vessel at sea.
Depression, giddiness, nausea and vomiting are the most prominent.
Causes Although the vast majority of people appear to be liable to this ailment at sea, they do not all suffer alike. Many endure acute distress, whilst others are simply conscious of transient feelings of nausea and discomfort. A smaller proportion of people suffer from air and car sickness. The symptoms are a result of over-stimulation of the organs of balance in the inner EAR by continuous changes in the body’s position. The movements of the horizon worsen this situation.
Symptoms The symptoms generally show themselves soon after the journey has started, by the onset of giddiness and discomfort in the head, together with a sense of nausea and sinking at the stomach, which soon develops into intense sickness and vomiting. Most people recover quickly when the motion stops.
Treatment Innumerable preventives and remedies have been proposed. Cinnarizine 30 mg orally is useful 2 hours before travel, then 15 mg every 8 hours during the journey if necessary. Dimenhydrinate and promethazine are also commonly taken for motion sickness.... motion (travel) sickness
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