Generic Name: cyproheptadine

Drug Class: Antihistamines, 1st Generation

What is cyproheptadine, and what is it used for?

Cyproheptadine is a medication used to prevent and treat allergic reactions including sneezing, runny nose, watery eyes, swelling, itching, rashes and hives. Cyproheptadine is also used to prevent migraines and to manage severe life-threatening allergic reactions (anaphylaxis). Cyproheptadine is a first generation antihistamine which easily crosses the blood-brain barrier, causing drowsiness as a side effect, which the second generation antihistamines do not cause.

Cyproheptadine blocks the activity of histamine, a natural compound in the body that causes the allergy symptoms. Histamine is released by mast cells and basophils, types of immune cells, in response to allergen exposure. Cyproheptadine binds to histamine H1 receptors in blood vessels, respiratory tract and gastrointestinal tract, preventing their stimulation by histamine and the resultant allergic reaction.

Cyproheptadine also binds to serotonin 5-HT2 receptors and blocks serotonin from stimulating them. Serotonin is an important chemical neurotransmitter in the brain that regulates many functions including sleep, appetite and memory by activating different sets of receptors on the nerve cells (neurons). Serotonin plays a role in migraine by stimulating 5-HT receptors which causes constriction of blood vessels in the brain, and cyproheptadine prevents this activity.

Serotonin reduces appetite and blocking its effect in the appetite center in the hypothalamus may help stimulate appetite. Cyproheptadine inhibits another neurotransmitter acetylcholine which causes muscle contractions, and may help relieve bronchospasms in severe allergic reactions. Cyproheptadine may also block calcium channels in the neurons, inhibiting the action potential for transmission of pain signals.

Cyproheptadine is approved to treat both adults and children with allergic conditions that include:

Off-label uses include:



What are the side effects of cyproheptadine?

Common side effects of cyproheptadine include:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Latest Allergies News

Daily Health News

Trending on MedicineNet

What are the dosages of cyproheptadine?


Oral solution


Hypersensitivity reaction

  • 4 mg orally every 8 hours initially; maintenance: 4-20 mg/day, up to 32 mg/day divided every 8 hours in some patients; not to exceed 0.5 mg/kg/day

Spasticity associated with spinal cord (off-label)

  • 2-4 mg orally every 8 hours initially; not to exceed 24 mg/day

Migraine headache prophylaxis (off-label)

  • 2 mg orally every 12 hours with or without propanol

Decreased appetite secondary to chronic disease (off-label)

  • 2 mg orally every 6 hours for one week; THEN 4 mg every 6 hours

Drug-induced sexual dysfunction (off-label)

  • 4-12 mg orally 1-2 hours before anticipated coitus or 1-16 mg/day

Serotonin syndrome (off-label)

  • 12 mg initially orally, followed by 2 mg every 2 hours or 4-8 mg orally every 6 hours as needed to control symptoms

Dosing Modifications

  • Nonanticholinergic antihistamines should be considered first when treating allergic reactions (Beers Criteria)
  • Advanced age is associated with reduced clearance and greater risk of confusion, dry mouth, constipation, and other anticholinergic effects and toxicity; use lower end of dosage range (4 mg orally every 12 hours) for elderly patients, or administer less frequently
  • Renal impairment: Elimination is reduced in renal insufficiency; administer lower doses, and monitor closely


Hypersensitivity Reaction

  • Children younger than 2 years old: Safety and efficacy not established
  • Children 2-6 years old: 2 mg orally every 8-12 hours; not to exceed 12 mg/day
  • Children 7-14 years old: 4 mg orally every 8-12 hours; not to exceed 16 mg/day
  • Alternatively, total daily dose of 0.25 mg/kg or 8 mg/m²



  • Children younger than 3 years: Safety and efficacy not established
  • Children older than 3 years and adolescents: 0.2-0.4 mg/kg/day orally divided twice daily; not to exceed 0.5 mg/kg/day

Loss of appetite (including anorexia nervosa; off-label)

Stimulation of appetite

  • Children younger than 13 years: Safety and efficacy not established
  • Children older than 13 years: 2 mg orally every 6 hours initially; increased to up to 8 mg every 6 hours over 3 weeks

Dosing Modifications

  • Renal impairment: Elimination is reduced in renal insufficiency; administer lower doses, and monitor closely


  • Cyproheptadine overdose effects may vary from central nervous system (CNS) depression to stimulation, especially in pediatric patients. It may also cause symptoms such as dry mouth, fixed, dilated pupils, flushing, and gastrointestinal symptoms.
  • Induced vomiting and gastric lavage may be performed followed by activated charcoal treatment to eliminate unabsorbed drug in the stomach. CNS symptoms are treated with symptomatic and supportive care.


Allergies can best be described as: See Answer

What drugs interact with cyproheptadine?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

  • Severe Interactions of cyproheptadine include:
  • Serious Interactions of cyproheptadine include:
    • calcium/magnesium/potassium/sodium oxybates
    • eluxadoline
    • metoclopramide intranasal
    • pitolisant
    • sodium oxybate
    • Cyproheptadine has moderate interactions with at least 220 different drugs.
  • Mild Interactions of cyproheptadine include:

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information.

Check with your doctor or health care provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • Cyproheptadine use may be acceptable during pregnancy; studies have not revealed impairment to fertility or fetal harm.
  • It is not known if cyproheptadine is excreted in breast milk; do not use while breastfeeding because many drugs are excreted in milk

What else should I know about cyproheptadine?

  • Take cyproheptadine exactly as prescribed; seek medical help immediately in case of overdose
  • Keep cyproheptadine safely out of reach of children
  • Cyproheptadine may affect mental alertness and physical ability; do not engage in activities such as driving or operating heavy machinery
  • Do not drink alcohol or take alcohol-containing drugs while on cyproheptadine therapy

Subscribe to MedicineNet’s Allergy and Asthma Newsletter

By clicking “Submit,” I agree to the MedicineNet Terms and Conditions and Privacy Policy. I also agree to receive emails from MedicineNet and I understand that I may opt out of MedicineNet subscriptions at any time.

Medically Reviewed on 4/9/2022