Periactin is the brand name for cyproheptadine an antihistamine medication used to relieve allergy symptoms and to stimulate appetite. It works by blocking histamine h1 receptors that are activated during allergic reactions reducing itching sneezing and runny nose. In addition it antagonizes serotonin 5-ht2 receptors which contributes to its anti-migraine and anti-pruritic effects. By inhibiting these receptors it decreases the physiological responses that cause swelling of blood vessels and nerve irritation. The drug is also prescribed to increase weight gain in patients with conditions such as cystic fibrosis or severe malnutrition. Its effects are achieved through competitive inhibition of these receptors leading to reduced histamine and serotonin mediated activity.

Periactin is a medication that contains the active ingredient cyproheptidine and functions as an antihistamine with antiserotonergic properties. It is primarily used to relieve symptoms of allergic reactions and to stimulate appetite in certain clinical situations. The drug works by blocking histamine h1 receptors and antagonizing serotonin 5-ht2 receptors in the central nervous system. This dual antagonism interrupts the pathways that trigger itching, hives, and migraines. By modulating these chemical signals the medication helps reduce the severity and frequency of allergic responses. The overall pharmacological profile supports both anti-allergic effects and appetite enhancement.

Periactin can cause drowsiness as a common side effect. Some users may experience dizziness or lightheadedness. Dry mouth and mild skin dryness are reported frequently. Blurred vision or sensitivity to light may occur temporarily. Occasional constipation or changes in appetite can be observed. Mild headache or fatigue may also appear.

Periactin is an antihistamine used to relieve allergy symptoms. Common side effects may include drowsiness and dizziness. Some people experience dry mouth thirst headache and nausea. Weight gain can occur due to increased appetite. Changes in vision or ringing in the ears are also reported occasionally. Most of these effects are mild and often improve with continued use. Serious reactions such as heart rhythm problems are rare and usually linked to very high doses.