Histamine Antagonists

Doxylamine

first generation H1 antihistamine used as an over the counter sleeping medication

Promethazine

First generation H1 antihistamine that has antiemetic properties and is also used as a sedative → sometimes in the hospital setting (most sedative)

Hydroxyzine

First generation H1 antihistamine with antiemetic properties and is used as a sedative / sleeping aid

Diphenhydramine

First generation H1 antihistamine used in the treatment of allergies such as contact dermatitis and hay fever, is used as a sedative, used in pulmonary medicine due to their ability to decrease respiratory secretion

Side effects of antihistamines

Dry mouth, dry-hot skin, constipation, urinary retention, sedation, drowsiness, confusion, amnesia

Dimenhydrinate

First generation H1 antihistamine used to prevent motion sickness and vertigo with moderate sedating actions

Chlorpheniramine maleate

First generation H1 antihistamine with moderately sedating actions

Meclizine

First generation H1 antihistamine used to prevent motion sickness and vertigo with moderate sedative actions

Loratadine

Second generation H1 antihistamine

Desloratidine

Second generation H1 antihistamine

Certirizine

Second generation H1 antihistamine

Levocertirizine

Second generation H1 antihistamine

Fexofenadine

Second generation H1 antihistamine

Azelastine

Second generation H1 antihistamine

Cimetidine

H2 antihistamine that is effective at reducing gastric acid secretion and widely used in the treatment of peptic ulcer disease

Drug interactions of Cimetidine

Inhibits hepatic microsomal drug metabolizing enzymes (CYP450) which will prolong the actions of any drugs metabolized by the liver

Therapeutic used of H2 antihistamines

Gastric ulcers, duodenal ulcers, and Zolinger Ellison syndrome

Famotidine

H2 antagonist with lesser side effects

Nizatidine

H2 antagonist with lesser side effects