Periactin Side Effects
Generic name: cyproheptadine
Note: This document contains side effect information about cyproheptadine. Some of the dosage forms listed on this page may not apply to the brand name Periactin.
Some side effects of Periactin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to cyproheptadine: oral syrup, oral tablet
Get emergency medical help if you have any of these signs of an allergic reaction while taking cyproheptadine (the active ingredient contained in Periactin) hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop taking cyproheptadine and call your doctor at once if you have a serious side effect such as:
confusion, hallucinations, unusual thoughts or behavior;
ringing in your ears;
feeling like you might pass out;
fast or pounding heartbeats;
easy bruising or bleeding;
urinating less than usual or not at all; or
pale or yellowed skin, dark colored urine, fever, or unusual weakness.
Less serious side effects of cyproheptadine may include:
mild drowsiness, dizziness, or spinning sensation;
feeling restlessness or excited (especially in children);
sleep problems (insomnia), tired feeling;
numbness or tingly feeling;
increased sweating or urination;
dry mouth or nose, upset stomach; or
nausea, diarrhea, constipation.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to cyproheptadine: compounding powder, oral syrup, oral tablet
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.
Gastrointestinal side effects have included dry mouth, diarrhea, constipation, nausea, and vomiting.
The effect of cyproheptadine (the active ingredient contained in Periactin) 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.
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.
Cardiovascular side effects have included hypotension, tachycardia, and palpitations.
Respiratory side effects have included dry nose and throat, thickening of bronchial secretions, chest tightness, and wheezing.
Ocular side effects have included blurred vision, diplopia, and dry eyes, due to the anticholinergic activity of the drug.
Genitourinary side effects have included urinary retention, urinary frequency and dysuria probably resulting from cyproheptadine (the active ingredient contained in Periactin) s anticholinergic activity.
Hematologic side effects have included hemolytic anemia, thrombocytopenia, and agranulocytosis, but these have been uncommon.
Hepatic side effects have included rare reports of cholestatic jaundice.
More Periactin resources
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