Medically Reviewed on 5/10/2023

What is Periactin, and what is it used for?

Periactin is an oral antihistamine used for treating various types of allergic reactions and the skin manifestations of allergic reactions.

Its off-label uses (non-FDA approved) include:

Periactin works by blocking the effects of histamine and is classified as a first generation antihistamine. Histamine is released by cells of the body during several types of allergic reactions and, to a lesser extent, during some viral infections, such as the common cold.

When the histamine binds to receptors on other cells, it stimulates changes within the cells that lead to the release of chemicals that cause sneezing, itching, and increased production of mucus. Antihistamines compete with histamine for cell receptors and bind to the receptors without stimulating the cells. In addition, they prevent histamine from binding and stimulating the cells.

Periactin also blocks the action of acetylcholine (anticholinergic effect) and serotonin, two neurotransmitters that nerves and muscles use to communicate with one another, and it causes drowsiness.

What are the side effects of Periactin?

Side effects of include:

Other side effects that have been reported include:

Antihistamines may reduce mental alertness, however, they may occasionally produce excitation in children.

Patients should be warned about driving a car or operating machinery and participating in other activities that require mental alertness and motor coordination.

Antihistamines may add to the sedative effects of alcohol, hypnotics, sedatives, tranquilizers, and anti-anxiety drugs.

Antihistamines are more likely to cause dizziness, sedation, and hypotension (low blood pressure) in elderly patients.

What is the dosage for Periactin?

  • The recommended starting dose for adults is 4 mg every 8 hours.
  • The dose range is 4 mg to 20 mg daily.
  • Some patients may require up to 32 mg day. The dose should not exceed 0.5 mg/kg daily.
  • The dosage for children 7 to 14 years of age should receive 4 mg 3 times daily. The maximum dose is 16 mg daily.
  • Children 2 to 6 years old are treated with 2 mg three times daily and the maximum dose is 12 mg a day.
  • The total daily dose may also be calculated by weight (0.25 mg/kg/day) or surface area (8 mg/m2).


Allergies can best be described as: See Answer

Which drugs interact with Periactin?

Periactin adds to the sedating effects of alcohol and other drugs like benzodiazepines, narcotics, tricyclic antidepressants, and high blood pressure (hypertension) medications, that can cause sedation.

1. Benzodiazepines is a class of drugs of anti-anxiety medications, for example:

2. Narcotics is a drug class of drugs of pain medications and its derivatives, for example:

3. Tricyclic's is a class of drugs of antidepressants, for example:

4. Certain antihypertensive medications, for example:

Periactin also can intensify the drying effects on moist tissues (such as the eye or mouth) of other medications with anticholinergic properties, for example, dicyclomine (Bentyl) and bethanechol (Urecholine), and probanthine.

Pregnancy and breastfeeding

  • Studies in women who are pregnant have not shown that Periactin harms the fetus during the first, second and third trimesters of pregnancy. However, these studies do not exclude the possibility of harm. Periactin should be used during pregnancy only if it is clearly needed.
  • It is not known whether Periactin is excreted in human milk.

What else should I know about Periactin?

  • This drug is available in the following preparations: Tablets: 4 mg; Oral Solution: 2 mg/5 ml
  • Store this medication should at room temperature, 15 C - 30 C (59 F - 86 F).
  • The FDA approved cyproheptadine in October 1961.


Periactin (cyproheptadine) is an antihistamine used to treat allergic reactions by blocking the histamines. The drug is used for various types of allergic reactions including skin reactions. Off-label (non-FDA approved) uses include spasticity associated with spinal cord injury and preventing migraine headaches. Review side effects, dosage, drug and supplement interactions, and pregnancy and breastfeeding safety information prior to taking this drug. Periactin, the brand name, has been discontinued.

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Medically Reviewed on 5/10/2023
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