Non-drowsy antihistamines are generally the best option, as they're less likely to make you feel sleepy.But types that make you feel sleepy may be better if your symptoms affect your sleep.Antihistamines are designed to block the effects of the histamine that your body produces.
It's stored in cells called mast cells, in almost all tissues of the body, and is released when the body reacts to a foreign substance (known as an allergen).
Anxiety and agitation with diffuse, deep, odd body sensations:"..bones are on fire", "I feel weird all over", "...a deep pricking, crawling sensation...".
Histamine carries its message to a large number of cells by attaching to a special receptor on the cells' surfaces.
Skin sensations local itching or burning sensation, flushing and a disagreeable heat.
Stomach pain acid secretion increases; small intestine contracts with crampy pain Respiratory - nose swelling, congestion, sneezing and wheezing.