Antihistamines Include: Ethanolamine- Carbinoxamine. Clemastine, Diphenhydramine. Ethylenediamines- Pyrilamine, Triplennamine Akylamines- Brompheneramine, Chlorpheniramine, Dexchlor pheniramine, Triprolidine Phenothiazines- Methidilazine, Promethizine Piperadines- Azatadine, Cyproheptadine, Phenindamine Miscellaneous- Astemazole, Loratadine, Terfenadine

Increased BP with other sympathomimetic agents, eg decongestants, TCA, appetite supressants

Reduced hypotensive effects of methyldopa , alpha and beta adrenergic blockers,

Increased side effects eg. somnolence, agitation with atomoxetine Increased risk of hypertensive crisis with furazolidone,

avoid concurrent use Increased risk of hypertensive crisis with MAOIs ,

avoid concurrent use within after 2 weeks of stopping

MAOIs Increased risk of psychosis with bromocriptine

Decongestant, antihistamine

Antihistamines Include: Ethanolamine- Carbinoxamine. Clemastine, Diphenhydramine. Ethylenediamines- Pyrilamine, Triplennamine Akylamines- Brompheneramine, Chlorpheniramine, Dexchlor pheniramine, Triprolidine Phenothiazines- Methidilazine, Promethizine Piperadines- Azatadine, Cyproheptadine, Phenindamine Miscellaneous- Astemazole, Loratadine, Terfenadine 

CNS depression, paradoxical excitation in children, Dry mouth, blurring of vision, constipation, Urinary retension, Bradycarda followed by tachycardia and arrhythmias. G.I.disturbances, Blood dyscrasias, Rash, Vertigo, dizziness, Ataxia, tinnitus, Parathesias, headache.

Hypersens, pregnancy, GI/urinary outflow obstruction, paralytic ileus.

Special precautions: Severe CVS disorder, epilepsy, lactation,diabetes, hypertension, BHP,elderly.

Indications: Decongestant, antihistamine

Dosage: 2.5 mg 4 times a day.

 1. Inform patients of a history of glaucoma, peptic ulcer, urinary retention, or pregnancy before starting antihistamine therapy

2. May cause nervousness, insomnia, and dry mouth

3. May cause drowsiness, or dizziness(except astemazole,loratadine, and tefenadine)

4. Patients should observe caution while driving or performing other tasks requiring alertness, coordination or physical dexterity.

5. Avoid alcohol and other CNS depressants (eg,. sedatives, hypnotics, tranquilizers)

6. May cause GI upset, take with food. Take Astemazole on an empty stomach, at least 2 hours after or 1 hour before a meal. Take Lorantidine on an empty stomach.

7. Avoid prolonged exposure to sunlight, may cause photosentivity.

8. Do not crush or chew sustained releae preparations

9.Astemazole/ Terfenadine: Patients should not take these agents if they have hepatic dysfunction or if they are also receiving ketoconazole, itraconazole or erythromycin

10. Phenothiazines- Patients should report any involuntary muscle movements or unusual sensitivity to sunlight.