Oxytocin

A nine-amino-acid hormone made in the brain and released from the pituitary. It triggers contractions in labor and milk let-down, and in the brain it shapes bonding and social reactions. As a drug it is Pitocin, an FDA-approved hospital injection for labor and bleeding after birth.

No nasal product is on the US market. Syntocinon nasal solution (40 USP units per mL) once had an approval, but Drugs@FDA lists it as discontinued. Today's sprays are compounded by pharmacies or made from research powder.

24 IU is the research standard. A review of 38 trials covered 18 to 40 IU, mostly as single doses. Community users report 20 to 40 IU once daily or before social events, and 10 to 20 IU for daily low-dose use.

Guides say 30 to 75 minutes. In a spinal-fluid study, 24 IU took up to 75 minutes to raise levels around the brain, even though blood levels peaked at 15 minutes.

The trials are underwhelming. In 29 couples, 24 IU did not change drive, arousal or erection but slightly raised orgasm intensity and contentment afterward. In 30 women with sexual dysfunction, 32 IU before sex for 8 weeks did no better than placebo, and both groups improved.

Different jobs. PT-141 works on melanocortin receptors and targets desire and arousal; oxytocin targets closeness and the after-orgasm feeling. Guides say PT-141 has much stronger libido evidence, and some people use both, PT-141 hours ahead and oxytocin 30 to 45 minutes before.

It varies a lot and no trial backs any of it. PeptIQ app users most often log 25 to 50 mcg per injection (range 0 to 400 mcg). One guide collects community protocols of 100 to 500 mcg once daily, and one vendor lists 20 to 50 mcg. The same guide argues injected oxytocin does not reach the brain the way nasal spray does.

2 mL (one vendor) or 3 mL (one guide); guides use 2 to 3 mL for 2 mg and 5 mg vials. At small doses the draw can fall under 2 units, so a finer 30-unit syringe helps. Enter your exact vial and water in a calculator.

About 1.67 mcg. The European Pharmacopoeia sets 1 mg of oxytocin as 600 IU for labelling, and the WHO International Standard (12.5 IU in about 21 mcg) agrees within 1%; this page uses 600 IU per mg. One vendor and one dosing guide say about 2 mcg per IU (1 mg is about 500 IU), which would put about 20% more peptide in each IU dose. Research vials vary in purity too, so dose by what your product is labeled in when you can.

Few in trials: a review of 38 studies found side effects no different from placebo at 18 to 40 IU. Guides list nasal irritation, transient headache and mild flushing. Community users most often mention thirst and strong emotional sensitivity, and many feel nothing at all.

At large doses, yes. The Pitocin label warns of water intoxication with convulsions from IV infusions of 40 to 50 milliunits per minute over long periods, and maternal deaths have been reported. That is far above nasal doses, but drinking big volumes of water around frequent dosing is a bad idea.

Not in the best trial so far. In 61 adults with obesity, 24 IU nasal four times a day for 8 weeks changed weight no more than placebo (0.20 vs 0.26 kg), though people ate 152 kcal less than the placebo group at a test meal.

The largest trial says no. In 290 children and teens, nasal oxytocin at a target of 48 IU a day for 24 weeks did no better than placebo on social withdrawal, and side effects were similar.

In the blood, minutes: the Pitocin label gives a half-life of about 1 to 6 minutes. Guides say behavioral effects of a nasal dose last roughly 30 to 120 minutes. After an IM shot, the uterine effect lasts 2 to 3 hours.

Pitocin vials stay at room temperature (20 to 25°C). A compounded nasal spray goes in the fridge. Research powder goes in the freezer or fridge, and a mixed vial lasts about 28 days in the fridge.

It is not named on the WADA 2026 Prohibited List, and as an approved drug it does not fall under the S0 class for unapproved substances.