Evidence: MediumPeptideResearch ChemicalEndogenous opioidNot a drugGiven in 1970s studies

Beta-Endorphin

Q: What is beta-endorphin?

A 31-amino-acid opioid peptide cut from proopiomelanocortin and released by the pituitary, acting at mu-opioid receptors, the same receptors morphine binds.

Q: Is it responsible for the runner's high?

It is the peptide usually named, and exertion raises it. The studies here measured it in stress, pain and labour rather than testing that explanation.

Q: Has it been injected into people?

Yes, in small studies around 1980. A single intravenous dose raised prolactin and changed the EEG like morphine, and in a later study it blunted provoked chest pain.

Q: Why was it never developed as a painkiller?

The human studies were tiny and nothing followed them. Like other endogenous opioids it is broken down quickly, and ordinary opioids act on the same receptor.

Q: Can a beta-endorphin blood test predict pain relief from opioids?

Not usefully. Resting plasma levels predicted morphine's effect on only 3 of 9 outcomes, and spinal-fluid levels before caesarean did not predict later opioid use.

Q: Do autistic people have high endorphins that block pain?

Studies do not support that. Autistic children expressed pain differently rather than feeling less, and beta-endorphin was not linked to self-injury or pain reactivity.

The pituitary opioid behind the runner's high, injected in a handful of small studies and never developed

Beta-endorphin is a 31-amino-acid opioid peptide cut from proopiomelanocortin and released by the pituitary under stress and exertion. Unlike the enkephalins it was given intravenously in small studies around 1980, where it blunted pain and changed the EEG much as morphine did.

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Overview

What is it?

Beta-endorphin comes from proopiomelanocortin, the same precursor as ACTH, and is released from the pituitary and the hypothalamus. It binds mu-opioid receptors, the receptors morphine acts on, which is why it is the peptide usually named in accounts of the runner's high.

It is one of the few endogenous opioids actually given to people. In small studies around 1980 it was injected intravenously: it produced EEG changes resembling morphine's, raised prolactin, and in a controlled pain study it blunted chest pain that met-enkephalin did not touch.

Most later human work measures it rather than gives it. Blood and spinal-fluid levels have been related to pain severity, to the premenstrual phase, and to acupressure in labour, and the steroid dexamethasone suppresses it along with cortisol, which places it in the stress-hormone axis.

As a measurement, it has mostly failed to predict anything useful. Resting plasma beta-endorphin predicted morphine's effect on only 3 of 9 pain outcomes, and lower spinal-fluid levels before a caesarean did not predict opioid use afterwards. In autism, an old theory held that excess endogenous opioids blunt pain and drive self-injury; studies of children found autistic children express pain differently rather than feel less, and found no link between beta-endorphin and self-injury.

Where it rises, the context matters. Levels were higher in severely affected autistic people, read as an acute stress response; they rose when flurbiprofen was added to opioids in refractory cancer pain; and they went with less depression after three months of exercise in myasthenia gravis. In mice, the benefit of electroacupuncture on nerve insulation in a multiple sclerosis model depended on beta-endorphin and opioid receptors.

Amino acids

cut from POMC, like ACTH

20 mg

Intravenous dose given around 1980

schizophrenia study, research only

3 of 9

Pain outcomes it predicted

resting plasma level and morphine relief

Science

Mechanism of Action

Beta-endorphin is a 31-amino-acid opioid peptide cut from proopiomelanocortin (POMC), the precursor of ACTH, and released from the pituitary and hypothalamus. It acts mainly on mu-opioid receptors, the receptors morphine uses.

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Pain

It is the body's own mu-opioid agonist; injected doses blunted provoked chest pain in a small study.

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Stress

It is released with ACTH, and levels rise in acute stress responses.

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Brain and hormones

Intravenous doses changed the EEG like morphine and raised prolactin.

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Nerve repair (animal)

In a mouse model of multiple sclerosis it mediated remyelination through opioid receptors.

Evidence

Published Research

These are the studies in people, read from their PubMed abstracts: three that gave it intravenously and three that measured it.

Human1996

It blunted provoked chest pain

In seven healthy volunteers given adenosine to provoke chest pain in a double-blind study, intravenous beta-endorphin counteracted the pain (p < 0.01) while met-enkephalin did not.

PMID: 8905708

Human1980

Injected in schizophrenia

Nine men with chronic schizophrenia received a single intravenous 20 mg dose of beta-endorphin or saline in a double-blind crossover. Serum prolactin rose significantly. Symptom scores improved significantly in eight patients, which the authors describe as not clinically obvious.

PMID: 7387335

Human1979

EEG changes like morphine's

In one patient given beta-endorphin, morphine and saline intravenously on separate occasions under double-blind conditions, beta-endorphin and morphine both increased alpha power on the EEG within 5 to 15 minutes, distinguishable from two saline injections.

PMID: 298341

Human1984

Spinal-fluid levels and pain severity

In 24 patients having myelography for suspected disc disease, spinal-fluid beta-endorphin-like immunoreactivity ran inversely with their pain ratings for the preceding 24 hours (r = -0.59, p < 0.001). Mood ratings showed no such relationship.

PMID: 6322046

Human1985

Dexamethasone suppresses it

In six healthy subjects, 2 mg of oral dexamethasone significantly lowered plasma beta-endorphin along with cortisol (15.3 to 9.1 pg/mL) while placebo did not. A less specific assay missed the change, which the authors use to show how much the measurement method matters.

PMID: 2930864

Human2022

Acupressure in labour

In 140 women in labour randomised to conventional, warm or cold acupressure at the LI4 point or to no acupressure, the three acupressure groups reported more pain relief and had higher plasma beta-endorphin levels than the control group.

PMID: 35193802

Human2017

Does resting level predict opioid relief?

In people with and without chronic pain given morphine under controlled conditions, resting plasma beta-endorphin predicted morphine's pain relief on only 3 of 9 outcomes, moderated by chronic pain status. The authors conclude it is unlikely to be a clinically useful predictor.

PMID: 27183154

Human2023

Spinal-fluid levels before caesarean

In healthy women having a scheduled caesarean, lower beta-endorphin in spinal fluid before surgery did not predict more opioid use afterwards, although spinal-fluid and plasma levels were linked with some pain measures at 48 hours and 2 weeks.

PMID: 37502834

Human2014

Refractory cancer pain

In patients with refractory cancer pain, adding intravenous flurbiprofen axetil to opioids improved pain relief and raised plasma beta-endorphin (62.4 vs 45.8 pg/mL in the opioid-only group), which the authors propose as the mechanism.

PMID: 25605189

Human2023

Exercise in myasthenia gravis

In myasthenia gravis, a three-month exercise programme improved quality of life, anxiety and depression scores, daily activity and walking distance, and the fall in depression went with higher beta-endorphin.

PMID: 36781738

Human1997

Stress hormones in autism

Plasma beta-endorphin and ACTH were higher in autistic individuals than in controls, driven by the more severely affected, which the authors read as a heightened acute stress response rather than chronically raised stress-system activity.

PMID: 9315980

Human2009

Pain reactivity in autistic children

In children and adolescents with autism, apparently reduced pain sensitivity reflected a different way of expressing pain, not endogenous analgesia, and did not support opioid theories of autism. The authors stress that autistic children feel pain.

PMID: 19707566

Human2018

Self-injury and pain in autism

In autistic children and adolescents, beta-endorphin levels were not related to self-injurious behaviour or to pain reactivity in any of three observed situations, which further undermines the opioid theory of autism.

PMID: 29617065

Animal2025

Electroacupuncture and remyelination in mice

In mice with experimental autoimmune encephalomyelitis, a model of multiple sclerosis, electroacupuncture promoted remyelination through beta-endorphin acting on opioid receptors, and blocking opioid receptors removed the benefit.

PMID: 41277766

Dosing

Dosing Data

Beta-endorphin is not an approved medicine. The doses on record are single intravenous research doses from around 1980.

This is a single research dose from a small 1980 study, not a treatment dose. Beta-endorphin acts on the same receptors as morphine. See a doctor first; no beta-endorphin product is approved.

ProtocolDoseFrequencyDurationRoute

Study: chronic schizophrenia, double-blind crossover Human studyPMID 738733520 mgSingle doseSingle sessionIntravenous

Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.

One historical research dose

The only human dose here is a single 20 mg intravenous injection from a 1980 study. There is no treatment dose.

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Safety

Side Effects & Contraindications

Reported Side Effects

From the studies that gave it intravenously, each in fewer than ten people.

● Raised serum prolactin after a single 20 mg intravenous dose

● EEG changes resembling morphine's within 5 to 15 minutes

● No adverse effects were described in the abstracts of these studies, which were small and short

Contraindications & Cautions

Not a medicine.

● Any use outside a supervised research study

● It is a mu-opioid agonist; the human studies are single doses in fewer than ten people each, so nothing is known about repeated use

Regulatory

Legal Status

Beta-endorphin is not a medicine.

JurisdictionStatusNotes

United StatesNot approvedNo application for beta-endorphin appears in Drugs@FDA (openFDA, read October 1, 2026). The human studies above were research.

Sport (WADA)Prohibited (S0 catch-all)Not named on the 2026 List. The S0 catch-all covers any pharmacological substance with no current approval by any governmental regulatory health authority for human therapeutic use — which, on its face, captures this. Inference, not a WADA ruling: confirm with Global DRO or your anti-doping organisation. Still not named in the 2027 List (published September 21, 2026; in force January 1, 2027); S0's text now lists “peptides” among its examples of non-approved substances. Source: the 2026 and 2027 WADA Prohibited Lists, read on September 27, 2026.

Questions

Frequently Asked Questions

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