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Beta-Endorphin31 residuesYGGFMTSEKSQTPLVTLFKNAIIKNAYKKGEEach bubble = one amino acid. Size = residue mass. Color = chemical class.Also known as: β-endorphin, beta-EP, β-EP
Thirty-one amino acids, 18 to 33 times more potent than morphine, and your body makes it for free. Beta-endorphin is the strongest pain-killing molecule the human body produces. It floods your system during intense exercise, acute trauma, and childbirth, binding mu-opioid receptors with nanomolar affinity. The catch: injecting it doesn't replicate that experience. Subcutaneous beta-endorphin can't cross the blood-brain barrier, so systemic dosing produces hormonal shifts (LH suppression, prolactin rise) without the CNS analgesia or mood effects people typically want. Researchers still study it to understand endogenous opioid pharmacology, but clinical development was abandoned in the 1990s.
Eighteen to thirty-three times the analgesic potency of morphine on a molar basis. That number alone explains why beta-endorphin attracted intense research interest after Choh Hao Li and David Chung first isolated it from camel pituitary glands in 1976 [1]. Beta-endorphin (CAS 61512-77-4) is a 31-amino-acid peptide cleaved from the C-terminal end of pro-opiomelanocortin (POMC), the same precursor protein that gives rise to ACTH and alpha-MSH. The arcuate nucleus of the hypothalamus and the anterior pituitary are the primary production sites. Once released, it binds mu-opioid receptors with a Ki of roughly 1 to 3 nM and also acts at delta-opioid receptors. In practical terms, your body releases beta-endorphin during intense exercise, acute pain, physical trauma, and labor. Plasma levels spike; the "runner's high" is partly attributed to this peptide [2]. Beyond pain modulation, it influences immune function by modulating natural killer cell activity, regulates appetite through hypothalamic feeding circuits, and participates in reward pathways that overlap with those activated by exogenous opioids. The clinical trajectory peaked in the early 1980s. Foley and colleagues administered 5 to 10 mg IV to cancer pain patients and documented clear analgesia [3]. One early clinical study showed 3 mg intrathecal produced analgesia lasting roughly 33 hours. Then research stopped. Rapid enzymatic degradation, blood-brain barrier impermeability from systemic routes, and morphine-equivalent dependency risk made synthetic opioids the more practical analgesic path. No modern development pipeline exists. Beta-endorphin today is a research reagent, not a therapeutic candidate.
Beta-endorphin's primary target is the mu-opioid receptor (MOR). Binding activates Gi/Go proteins and triggers three downstream cascades simultaneously. First, adenylyl cyclase is inhibited, dropping intracellular cAMP. Second, voltage-gated N-type calcium channels close, reducing neurotransmitter release from presynaptic terminals. Third, G-protein-coupled inwardly rectifying potassium channels (GIRKs) open, hyperpolarizing the membrane. The net result at the spinal level: nociceptive signals get suppressed at dorsal horn synapses. Pain transmission slows. In the periaqueductal gray and rostral ventromedial medulla, beta-endorphin works through disinhibition. It suppresses tonically active GABAergic interneurons, which releases the brakes on descending serotonergic and noradrenergic analgesic pathways. Pain signals heading up get blocked; pain-suppressing signals heading down get amplified. Beyond pain, arcuate nucleus POMC neurons release beta-endorphin onto mu-opioid receptors in the ventral tegmental area. This modulates dopaminergic signaling in the nucleus accumbens, contributing to reward processing and stress resilience. The immune system also responds. T-lymphocytes, B-cells, and natural killer cells express mu-opioid receptors; beta-endorphin binding alters cytokine release and cellular immune responses. Signal termination happens fast. Aminopeptidase N and enkephalinase (neprilysin/CD10) degrade the peptide in plasma within 20 to 35 minutes. That short window is one reason clinical development never progressed.
No published SC dosing protocol exists in humans. All clinical exogenous administration used IV or intrathecal routes at milligram-range doses (2.5–10 mg IV; 3 mg intrathecal). Demonstrated acute analgesia, LH suppression, and prolactin rise. SC mcg-range dosing tiers have zero clinical basis. BBB impermeability confirmed: systemic administration does not produce CNS effects.
Foley et al. 1979 (PMID 291954): IV 5–10 mg produced analgesia in cancer patients; plasma t½ ~37 min (not 27 min as in pkData)
All human exogenous dosing data from 1978–1992; no SC data; full mu-opioid agonist carries morphine-equivalent dependency risk; BBB impermeability limits CNS access from systemic routes; rapid enzymatic degradation (aminopeptidase N, enkephalinase); research pipeline abandoned in 1990s in favour of stable synthetic opioids
No self-administration community use documented. Absent from r/Peptides, r/nootropics, r/PeptidesSourceTalk. Not available from gray-market peptide vendors. Prohibitive cost (~$155–$203/mg research-grade reagent; ~$78–$102/day at aggressive tier) prevents practical use.
Historical clinical literature demonstrates clear IV/intrathecal efficacy and hormonal effects. Self-administration community use is effectively nonexistent. SC dosing tiers in the database are unvalidated extrapolations with no clinical counterpart and are explicitly disclaimed as speculative.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 100mcg | EOD |
| Moderate | 250mcg | EOD |
| Aggressive | 500mcg | Daily |
No subcutaneous dosing protocol has ever been tested in humans. The 100 to 500 mcg SC doses listed are speculative extrapolations with zero clinical basis. Every human study used IV (2.5 to 10 mg) or intrathecal (3 mg) routes, and SC at microgram-range doses sits 10 to 100x below those studied amounts. Reconstitution math for reference: a 1 mg vial with 2 mL bacteriostatic water gives you 500 mcg/mL, so 250 mcg equals 0.5 mL (50 units on an insulin syringe). At research-reagent pricing of $155 to $203 per milligram, that single vial costs roughly $155 to $203, and a 500 mcg dose runs about $78 to $102. SC injection won't cross the blood-brain barrier. You'll get peripheral hormonal changes (LH drops, prolactin goes up, cortisol shifts) but no CNS analgesia or mood effects. If the goal is boosting the endogenous endorphin system, low-dose naltrexone (1.5 to 4.5 mg nightly) works in the opposite direction and has actual clinical evidence behind it.
Due to limited human clinical data, cycling recommendations are extrapolated from general opioid peptide pharmacology. Conservative protocols suggest a maximum of 4 weeks of intermittent use followed by an equal off period to minimize the risk of tolerance development and HPA axis suppression. Monitoring of mood, pain sensitivity, and endocrine markers is recommended during and after the on-cycle. Abrupt cessation after prolonged use may produce rebound effects.
Chronic mu-opioid receptor activation by beta-endorphin triggers MOR downregulation via beta-arrestin recruitment, receptor internalisation, and reduced cAMP signalling efficiency. Concurrent POMC axis suppression reduces endogenous beta-endorphin synthesis in the arcuate nucleus. The 4-weeks-on / 4-weeks-off protocol in peptides.ts is extrapolated from general opioid pharmacology to allow MOR resensitisation and POMC axis recovery. No beta-endorphin-specific cycling data exists in humans. Secondary rationale: hormonal-axis-recovery (HPA and HPG axes require off-cycle recovery time to restore cortisol, ACTH, LH, and sex hormone baseline).
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Expected: Transient analgesia; measurable LH suppression, prolactin rise, and cortisol modulation. CNS effects (mood, reward) not produced via IV at these doses without direct CNS delivery.
Monitor: Continuous respiratory monitoring (RR, SpO2), blood pressure, pulse oximetry. Naloxone 0.4 mg IV reversal agent required on site.
Reconstitute the lyophilized powder by adding 2 mL of bacteriostatic water slowly along the vial wall. Swirl gently until dissolved. Do not shake or vortex.
For a 1 mg vial reconstituted with 2 mL, the concentration is 500 mcg/mL. A 100 mcg dose equals 0.2 mL (20 units on an insulin syringe). A 250 mcg dose equals 0.5 mL (50 units). A 500 mcg dose equals 1.0 mL (100 units, a full syringe).
For a 2 mg vial reconstituted with 2 mL, the concentration is 1000 mcg/mL. A 100 mcg dose equals 0.1 mL (10 units). A 250 mcg dose equals 0.25 mL (25 units). A 500 mcg dose equals 0.5 mL (50 units).
Use a 29 to 31 gauge insulin syringe for subcutaneous injection. Inject into abdominal or upper thigh tissue. Rotate injection sites each time.
No specific timing relative to meals or sleep has been established. All dosing schedules are speculative.
Use within 14 days. Do not freeze reconstituted solution.
Pulse oximetry monitoring (SpO2) and respiratory rate checks should accompany every administration, even at SC doses. Naloxone should be accessible.
2.5–10 mg (milligram range); 100% bioavailability; immediate onset; t½ ~37 min
Foley 1979 (5–10 mg, cancer pain analgesia) and Reid 1981 (2.5 mg, LH/prolactin study). Requires clinical setting, trained staff, resuscitation equipment. Not self-administrable.
3 mg; direct CSF delivery; profound analgesia sustained ~33 hours
Oyama 1980 data. Completely bypasses BBB limitation of systemic routes. Requires neurosurgical/anaesthesiological administration in hospital setting. Not appropriate outside clinical research.
Community-speculated 100–500 mcg; far below mg-range studied doses; SC bioavailability estimated 40–60% but dose magnitude difference is 10–100×
SC produces peripheral hormonal changes only. BBB impermeability confirmed: CNS analgesic and reward effects require intrathecal or ICV delivery. SC mcg-range doses are 5–100× below any studied IV dose.
Unknown; no published data for beta-endorphin
Beta-endorphin MW ~3,465 Da and hydrophilic character likely limits intranasal CNS bioavailability. Intranasal opioid delivery studied for small-molecule opioids (fentanyl) but not for endogenous opioid peptides of this size.
Additive mu-opioid receptor activation; potentiated respiratory depression; potentially fatal CNS and respiratory compromise
Do not combinePotentiated CNS and respiratory depression via combined GABAergic and opioid-mediated sedation; significant overdose and death risk
Do not combineUnpredictable potentiation of opioid-mediated CNS effects; potential serotonin syndrome when combined with serotonergic opioid activity
Do not combineEstablished serotonin-opioid crosstalk at mu-opioid and serotonergic systems; may alter analgesic efficacy and mood effects unpredictably; potential for serotonin syndrome at higher doses
Respiratory depression is the primary acute safety risk. Beta-endorphin is a full mu-opioid agonist. That means the respiratory depression profile is pharmacologically equivalent to morphine, and naloxone must be available during any administration. This is not a peptide with a mild side effect profile. The limited human data comes entirely from IV and intrathecal studies conducted between 1978 and 1992. Foley's group [3] administered 5 to 10 mg IV to cancer patients and observed sedation, nausea, and dose-dependent respiratory depression requiring monitoring. Reid's 1981 study [5] documented significant LH suppression and prolactin elevation from a single 2.5 mg IV dose, confirming direct HPG axis effects. Published and anticipated side effects from the clinical literature: Serious: dose-dependent respiratory depression, CNS depression at higher doses, potential for physical dependence and tolerance with repeated dosing (established mu-opioid pharmacology), opioid-induced hyperalgesia on cessation. Common: sedation and drowsiness, nausea and vomiting, constipation and reduced GI motility, miosis, bradycardia, mild hypotension, pruritus at injection site, flushing. Hormonal: HPA axis suppression with repeated dosing (reduced cortisol, reduced ACTH). HPG axis suppression (LH suppression, testosterone/estradiol reduction) documented from even a single IV dose. Prolactin elevation via MOR-mediated dopamine suppression. There is no community side effect data. Fewer than five substantive threads exist across all Reddit peptide communities. Nobody is self-administering this peptide in practice. Individuals with any history of opioid use disorder face raised risk for adverse psychological responses and should not use exogenous beta-endorphin. Concurrent use with benzodiazepines, alcohol, or any CNS depressant creates potentiated respiratory depression risk that can be fatal. Pregnancy and breastfeeding are contraindicated due to potential neuroendocrine effects on the fetus. If respiratory rate drops below 12 per minute or SpO2 falls below 94%, stop immediately. Naloxone 0.4 mg IV is the reversal agent. This peptide should never be administered without respiratory monitoring equipment and trained clinical staff.
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Research-reagent-only compound; no pharmaceutical-grade human-use product exists; no gray-market peptide vendors supply it. Sold by laboratory chemical suppliers (Thermo Fisher, Abbiotec, CPC Scientific, GenScript) as a lyophilised research standard. Purity, sterility, and endotoxin testing standards vary by supplier and are intended for in-vitro/ex-vivo use, not injection. Contamination with related POMC fragments (alpha-endorphin, gamma-endorphin, beta-lipotropin) is a potential quality concern.
| Test | When | Target |
|---|---|---|
| Morning serum cortisol | Baseline, week 2 (mid-cycle), end of cycle, and 2 weeks post-cycle | 10–20 mcg/dL (morning, pre-dose) |
| ACTH (plasma) | Baseline and end of cycle | 7–63 pg/mL (morning) |
| LH, FSH, total testosterone (males) / LH, FSH, estradiol (females) | Baseline and end of cycle | LH: 1.5–9.3 mIU/mL; Total T (males): 300–1000 ng/dL; Estradiol (females): cycle-appropriate |
| Prolactin | Baseline and mid-cycle | 2–18 ng/mL (males); 2–29 ng/mL (non-pregnant females) |
| Respiratory rate and SpO2 (pulse oximetry) | During and 30–60 minutes post each administration | RR ≥ 12/min; SpO2 ≥ 95% |
| Validated pain sensitivity baseline (e.g., pressure pain threshold or cold pressor test) | Baseline, mid-cycle (week 2), and end of cycle | — |
Chronic MOR activation suppresses CRH → ACTH → cortisol axis; HPA suppression is a primary risk with repeated dosing
Direct marker of pituitary axis suppression; falls before cortisol in early HPA suppression
HPG axis suppression documented from a single 2.5 mg IV dose (Reid 1981 PMID 6262367); chronic dosing expected to cause opioid-induced hypogonadism (OPIAD)
Reid 1981 documented significant prolactin elevation from single IV dose via MOR-mediated dopamine suppression; persistent elevation may indicate axis disruption
Full mu-opioid agonist; dose-dependent respiratory depression is the primary acute safety risk
Opioid-induced hyperalgesia (OIH) surveillance; worsening pain threshold is the primary indicator of MOR tolerance and OIH progression, warranting discontinuation
Rapid onset of analgesic and mild euphoric effects following IV administration in preclinical models
Peak plasma concentration reached; maximal analgesic response and measurable HPA axis modulation
Gradual decline of analgesic effect as peptide is enzymatically degraded; secondary immune modulation effects may persist
With repeated intermittent dosing, potential cumulative effects on mood and stress response observed in animal models
Risk of tolerance development increases; monitoring for reduced analgesic efficacy and rebound hyperalgesia recommended
0 to 30 minutes (Onset, route-dependent): IV administration produces immediate analgesic onset within minutes. SC dosing reaches estimated Cmax around 15 to 30 minutes based on PK extrapolation. Plasma half-life runs about 37 minutes via IV (Foley 1979)[3]. HPA axis changes begin quickly: cortisol drops, ACTH drops, LH falls, and prolactin rises. Side effects at this stage include sedation, nausea, pruritus, mild hypotension, bradycardia, and miosis. No community user data exists for any route. 30 minutes to 4 hours (Plasma elimination): Aminopeptidase N and enkephalinase break the peptide down rapidly. IV analgesic effects fade by 2 to 4 hours. Intrathecal dosing (3 mg) is the outlier; that route sustained analgesia for roughly 33 hours by bypassing plasma degradation entirely. Hormonal perturbations from IV dosing normalize within 1 to 2 hours. Residual sedation, constipation, and possible rebound dysphoria may follow peptide clearance. 1 to 2 weeks (Repeated dosing): MOR downregulation begins through beta-arrestin recruitment and receptor internalization. Cumulative HPA and HPG suppression builds. Animal models show reduced endogenous beta-endorphin synthesis with chronic exogenous opioid exposure as arcuate nucleus POMC output drops. Expect diminished analgesic response from the same dose, worsening baseline pain sensitivity, hormonal dysregulation, and mood decline. 4 or more weeks (Dependence and OIH risk): Opioid-induced hyperalgesia is the pharmacological prediction from established opioid science. Physical dependence equivalent to morphine is anticipated with daily dosing. POMC axis suppression becomes measurable. Abrupt cessation after sustained use is expected to trigger opioid withdrawal: anxiety, sweating, GI distress, insomnia, and pain sensitization. No beta-endorphin-specific long-term human data exists. No taper protocol has been published.
IV: immediate onset, analgesic within minutes. SC: estimated 15–30 min to Cmax based on PK extrapolation. Plasma t½ ~37 min (IV, Foley 1979). HPA modulation (cortisol↓, ACTH↓) and HPG changes (LH↓, prolactin↑) begin.
No community data: no self-administration reports documented.
Peptide degraded by aminopeptidase N and enkephalinase (neprilysin/CD10). Analgesic effect wanes by ~2–4 hours IV. Intrathecal administration (3 mg): analgesia persists ~33 hours (Oyama 1980). Hormonal perturbations (LH, prolactin, cortisol) normalise within 1–2 hours after IV dosing.
No community data.
MOR downregulation begins with repeated activation (beta-arrestin recruitment, receptor internalisation). Cumulative HPA and HPG suppression. Animal models show reduced endogenous beta-endorphin synthesis with chronic exogenous opioid exposure (arcuate POMC downregulation).
No community data.
Opioid-induced hyperalgesia (OIH) is predicted by established opioid pharmacology. Physical dependence with mu-opioid pharmacology equivalent to morphine anticipated with daily dosing. POMC axis suppression measurable. Abrupt cessation expected to precipitate opioid withdrawal syndrome. No beta-endorphin-specific long-term human data exists.
No community data.
Source: Foley et al., 1979: plasma elimination studies in humans following IV infusion
Loading the interactive decay curve.
Beta-endorphin holds no FDA approval for any therapeutic indication. It has never completed a clinical development program and has no IND or NDA on file. Current regulatory status: research-only compound. The peptide is sold exclusively by laboratory chemical suppliers (Thermo Fisher, Abbiotec, CPC Scientific, GenScript) as a lyophilized research reagent intended for in-vitro and ex-vivo use. No compounding pharmacy supplies beta-endorphin for human injection. No gray-market peptide vendor carries it either. WADA classification: beta-endorphin falls under S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) on the Prohibited List. Athletes should consider any exogenous opioid peptide a potential doping violation. This content is for educational and research reference only. Beta-endorphin is not approved for human therapeutic use. Consult a qualified healthcare provider before considering any peptide research protocol.
Peptide Schedule Research TeamReviewed Apr 20269 Citations
