Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 866144
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
INDICATIONS AND USAGE Perennial and seasonal allergic rhinitis Vasomotor rhinitisAllergic conjunctivitis due to inhalant allergens and foodsMild, uncomplicated allergic skin manifestations of urticaria and angioedema.Amelioration of allergic reactions to blood or plasmaCold urticariaDermatographism As therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after the acute manifestations have been controlled.
About this medicine
DESCRIPTION Cyproheptadine HCl, is an antihistaminic and antiserotonergic agent. Cyproheptadine hydrochloride, USP is a white to slightly yellowish crystalline solid, with a molecular weight of 350.89, which is soluble in water, freely soluble in methanol, sparingly soluble in ethanol, soluble in chloroform, and practically insoluble in ether. It is the sesquihydrate 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine hydrochloride. The molecular formula of the anhydrous salt is C 21 H 21 N•HCl and the structural formula of the anhydrous salt is as follows: C 21 H 21 N• HCl M.W. 350.89 Cyproheptadine hydrochloride, USP is available for oral administration in 4 mg tablets. Each tablet contains: Inactives: Lactose Monohydrate, Microcrystalline Cellulose, Sodium Starch Glycolate and Magnesium Stearate. structure
Who should not take it
CONTRAINDICATIONS Newborn or Premature Infants This drug should not be used in newborn or premature infants. Nursing Mothers Because of the higher risk of antihistamines for infants generally and for newborns and prematures in particular, antihistamine therapy is contraindicated in nursing mothers. Other Conditions Hypersensitivity to cyproheptadine and other drugs of similar chemical structure. Monoamine oxidase inhibitor therapy (See DRUG INTERACTIONS .)Angle-closure glaucomaStenosing peptic ulcerSymptomatic prostatic hypertrophyBladder neck obstructionPyloroduodenal obstructionElderly, debilitated patients
Warnings
WARNINGS Pediatric Patients Overdosage of antihistamines, particularly in infants and young children, may produce hallucinations, central nervous system depression, convulsions, respiratory and cardiac arrest, and death. Antihistamines may diminish mental alertness; conversely, particularly, in the young child, they may occasionally produce excitation. CNS Depressants Antihistamines may have additive effects with alcohol and other CNS depressants, e.g., hypnotics, sedatives, tranquilizers, antianxiety agents. Activities Requiring Mental Alertness Patients should be warned about engaging in activities requiring mental alertness and motor coordination, such as driving a car or operating machinery. Antihistamines are more likely to cause dizziness, sedation, and hypotension in elderly patients (see PRECAUTIONS , Geriatric Use ).
Reported side effects
ADVERSE REACTIONS Adverse reactions which have been reported with the use of antihistamines are as follows: Central Nervous System Sedation and sleepiness (often transient), dizziness, disturbed coordination, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, paresthesias, neuritis, convulsions, euphoria, hallucinations, hysteria, faintness. Integumentary Allergic manifestation of rash and edema, excessive perspiration, urticaria, photosensitivity. Special Senses Acute labyrinthitis, blurred vision, diplopia, vertigo, tinnitus. Cardiovascular Hypotension, palpitation, tachycardia, extrasystoles, anaphylactic shock. Hematologic Hemolytic anemia, leukopenia, agranulocytosis, thrombocytopenia. Digestive System Cholestasis, hepatic failure, hepatitis, hepatic function abnormality, dryness of mouth, epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation, jaundice. Genitourinary Urinary frequency, difficult urination, urinary retention, early menses. Respiratory Dryness of nose and throat, thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness. Miscellaneous Fatigue, chills, headache, increased appetite/weight gain.
Interactions with other medicines
Drug Interactions MAO inhibitors prolong and intensify the anticholinergic effects of antihistamines. Antihistamines may have additive effects with alcohol and other CNS depressants, e.g., hypnotics, sedatives, tranquilizers, antianxiety agents.
If too much is taken
OVERDOSAGE Antihistamine overdosage reactions may vary from central nervous system depression to stimulation especially in pediatric patients. Also, atropine-like signs and symptoms (dry mouth; fixed, dilated pupils; flushing, etc.) as well as gastrointestinal symptoms may occur. If vomiting has not occurred spontaneously , the patient should be induced to vomit with syrup of ipecac. If patient is unable to vomit , perform gastric lavage followed by activated charcoal. Isotonic or ½ isotonic saline is the lavage of choice. Precautions against aspiration must be taken especially in infants and children. When life threatening CNS signs and symptoms are present, intravenous physostigmine salicylate may be considered. Dosage and frequency of administration are dependent on age, clinical response, and recurrence after response. (See package circulars for physostigmine products.) Saline cathartics , as milk of magnesia, by osmosis draw water into the bowel and, therefore, are valuable for their action in rapid dilution of bowel content. Stimulants should not be used. Vasopressors may be used to treat hypotension. The oral LD 50 of cyproheptadine is 123 mg/kg, and 295 mg/kg in the mouse and rat, respectively.
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 16 February 2026. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.