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Cyproheptadine Side Effects

For the Consumer

Applies to cyproheptadine: oral solution, oral tablets

Side effects include:

Sedation, sleepiness (often transient), dizziness, disturbed coordination, restlessness, excitation.

For Healthcare Professionals

Applies to cyproheptadine: compounding powder, oral syrup, oral tablet

Nervous system

Nervous system side effects have commonly included central nervous system (CNS) depression, typically resulting in drowsiness and sedation. These effects have often been transient and often ceased with continued use. Motor skills have been be impaired. Infrequently, confusion, restlessness, nervousness, tremor, convulsions, and hallucinations have occurred.[Ref]


Gastrointestinal side effects have included dry mouth, diarrhea, constipation, nausea, and vomiting.[Ref]


The effect of cyproheptadine on weight gain has been studied in patients in whom weight gain would be beneficial, such as those suffering from anorexia nervosa. In healthy, thin individuals, weight gain of 4 kg in 56 days has been reported with a dosage of 12 mg orally per day.[Ref]

Other side effects have included weight gain. The mechanism of action is not known but appears to be related to appetite stimulation, although a decrease in physical activity resulting from the sedative effect of the drug may contribute to a small degree.[Ref]


Cardiovascular side effects have included hypotension, tachycardia, and palpitations.[Ref]


Respiratory side effects have included dry nose and throat, thickening of bronchial secretions, chest tightness, and wheezing.[Ref]


Ocular side effects have included blurred vision, diplopia, and dry eyes, due to the anticholinergic activity of the drug.[Ref]


Genitourinary side effects have included urinary retention, urinary frequency and dysuria probably resulting from cyproheptadine's anticholinergic activity.[Ref]


Hematologic side effects have included hemolytic anemia, thrombocytopenia, and agranulocytosis, but these have been uncommon.[Ref]


Hepatic side effects have included rare reports of cholestatic jaundice.[Ref]


1. Wortsman J, Soler NG, Hirschowitz J "Side effects of cyproheptadine ." Br Med J 1 (1978): 1217

2. Silverstone T, Schuyler D "The effect of cyproheptadine on hunger, calorie intake and body weight in man." Psychopharmacologia 40 (1975): 335-40

3. Watemberg NM, Roth KS, Alehan FK, Epstein CE "Central anticholinergic syndrome on therapeutic doses of cyproheptadine." Pediatrics 103 (1999): 158-60

4. Berger M, White J, Travis LB, Brouhard BH, Cunningham RJ 3d, Patnode R, Petrusick T "Toxic psychosis due to cyproheptadine in a child on hemodialysis: a case report." Clin Nephrol 7 (1977): 43-4

5. "Product Information. Periactin (cyproheptadine)." Merck & Co, Inc, West Point, PA.

6. Stiel JN, Liddle GW, Lacy WW "Studies of mechanism of cyproheptadine-induced weight gain in human subjects." Metabolism 19 (1970): 192-200

7. Noble RE "Effect of cyproheptadine on appetite and weight gain in adults." JAMA 209 (1969): 2054-5

8. Larrey D, Geneve J, Pessayre D, Machayekhi JP, Degott C, Benhamou JP "Prolonged cholestasis after cyproheptadine-induced acute hepatitis." J Clin Gastroenterol 9 (1987): 102-4

9. Karkalas Y, Lal H "Jaundice following therapy with imipramine and cyproheptadine." Clin Toxicol 4 (1971): 47-53

10. Henry DA, Lowe JM, Donnelly T "Jaundice during cyproheptadine treatment." Br Med J 1 (1978): 753

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.