Short-acting type H1 antihistamines these medications, including diphenhydramine (Benadryl), are the primary treatment of mild cases of hives and angioedema. These are available without a prescription and are inexpensive. However, they must be taken every 6-12 hours and cause sleepiness, which can interfere with normal activity.



Long-acting H1 antihistamines these may also be used for mild cases of hives and angioedema. These drugs, which include fexofenadine (Allegra) and cetirizine (Zyrtec), are available by prescription. They are more expensive than nonprescription antihistamines but need to be taken only every 12-24 hours and usually do not cause disruptive sleepiness. The long-acting and nonsedating H1 antihistamine loratadine (Claritin) is now available without a prescription and one 10 mg tablet per day may be an alternative for some patients.

Type H2 antihistamines these drugs such as ranitidine (Zantac), cimetidine (Tagamet), and famotidine (Pepcid) have also been found to improve the rash and swelling when given with the type H1 antihistamines. Type H2 antihistamines were developed to treat ulcers. The US Food and Drug Administration (FDA) has not approved treating hives or angioedema with these drugs, but most physicians feel this is an appropriate use.

Corticosteroids, these drugs suppress the allergic response of the immune system. They may be given by injection or by mouth. Examples are prednisone (Deltasone), methylprednisolone (Medrol), and dexamethasone (Decadron). They reduce the chance of the rash coming back. They also relieve symptoms, such as swelling and inflammation, but may take a few hours to work. For severe situations, corticosteroids may be given by an injection or infused through an IV line.

H1- and H2-blocking drugs hives that do not respond to type H1 and H2 antihistamines may be treated with another type of drug. An example is doxepin (Sinequan). These drugs are intended as antidepressants, but they also have strong antihistamine effects, blocking both H1 and H2 histamine reactions. They can be very sedating. The FDA has not approved treating hives with these drugs, but most physicians feel this is an appropriate use.

Severe hives and most cases of angioedema may require more intense treatment. Epinephrine is a prescription drug, usually injected or given through an IV line, that rapidly reverses the most severe allergic reactions, including anaphylactic shock. IV fluids, usually saline solution, are given to increase blood pressure.

Oxygen may be given through a tube in the nose or via face mask in case of breathing trouble. Other medications may be given as needed to reverse symptoms or raise blood pressure. People who have angioedema usually need hospitalization as the recurrence risk is high, even with improvement after the initial treatment. Some cases of severe hives may also require hospitalization.

The treatment of hives depends on the severity of the symptoms. For mild to moderately severe localized symptoms, a nonprescription antihistamine by mouth is usually adequate, along with skin care measures for comfort. For more severe cases, an injection or short course of a corticosteroid may be needed to rapidly reduce swelling and itching.