Antihistamines provide hayfever and allergy relief.
Route of administration- Oral tablets/ capsules or liquids, or nasal sprays. Some preparations are taken continuously and some are taken on demand. Main Effect- Antihistamines stop the effects of histamine. Most require an additional decongestant to counter nasal congestion (often available as a combination product). Side Effects- Some can cause drowsiness, but non-sedating types are available.