At a glance
Effects
- Lean muscle preservation / growth: Promotes anabolic signalling in skeletal muscle, supporting lean body mass gains or retention during a caloric deficit [2].
- Bone density support: Stimulates osteoblast activity and reduces osteoclast-driven bone breakdown, improving bone mineral density in preclinical and early clinical data [1].
- Body recomposition: Commonly reported for simultaneous fat loss and muscle gain due to anabolic effects and possible impact on leptin and lipid metabolism [4].
- Joint & tendon recovery: Lower doses are anecdotally reported to support connective tissue recovery, though controlled evidence is limited [2].
- No aromatization / no water retention: Does not convert to estrogen or DHT, so estrogen-driven side effects such as water retention are not expected from the compound itself [3].
SARM (non-steroidal)
~24 hours (once-daily dosing)
Oral (liquid or capsule)
≈14 days in urine (single 30 mg dose)
No FDA/EMA approval; WADA-banned
About Ostarine
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
How it works
Ostarine binds selectively to androgen receptors in muscle and bone tissue, triggering anabolic signalling — protein synthesis and muscle repair — while producing attenuated or partial agonist activity in androgenic tissues such as the prostate [1][3]. Because it does not undergo aromatization or 5-alpha-reduction, it produces no estrogen or DHT metabolites, which differentiates it from classic anabolic steroids [4]. The tissue-selectivity arises from a ligand-induced conformational change in the androgen receptor that recruits different co-regulators depending on cell type [3].
Risks & side effects
Most important: The most important risk is dose- and duration-dependent suppression of natural testosterone production: Ostarine can suppress luteinizing hormone and endogenous testosterone, potentially causing hormonal imbalance that persists after the cycle ends [5]. At higher doses or longer cycles (over 8 weeks / above 15 mg/day), post-cycle therapy to restore the hypothalamic-pituitary-gonadal axis is strongly advised [6].
Common
Serious
- Elevated liver enzymes / hepatic stress at ergogenic or prolonged doses [6]
- Relative estrogen excess (gynecomastia risk) from testosterone suppression without direct aromatization [6]
- Adverse lipid changes (HDL reduction) with cardiovascular implications [7]
- Prolonged hormonal disruption requiring medical PCT if the HPG axis does not recover spontaneously [5]
Safety & harm reduction
- Pregnancy or breastfeeding — no safety data exist
- Pre-existing liver disease or elevated baseline liver enzymes [7]
- Pre-existing cardiovascular disease or high-risk lipid profiles [7]
- Individuals under 21 whose hormonal axes are still maturing
- Competitive athletes in WADA- or NCAA-tested sports — banned substance [9]
- Other SARMs stacked simultaneously may compound testosterone suppression and liver stress [2]
- CYP450-metabolised medications — Ostarine is processed hepatically; pharmacokinetic interactions possible [2]
- Aromatase inhibitors: may be considered if relative estrogen excess symptoms emerge, but should not be used prophylactically without bloodwork [6]
- Cycle length should generally not exceed 8 weeks at recreational doses [6]
- For cycles >8 weeks or doses >15 mg/day, a 4-week PCT with Nolvadex or Enclomiphene is widely recommended [6]
- Blood work before, mid-cycle, and 4–6 weeks post-cycle is the only reliable way to confirm recovery [9]
- Do not self-administer without baseline bloodwork — testosterone suppression can be asymptomatic initially [9]
Dosage context
No officially approved dosage exists as Ostarine has not received regulatory approval for any indication [9]. In clinical studies, doses as low as 1–3 mg/day produced measurable anabolic effects [8]. Community-reported ranges commonly cited are 10–20 mg/day for general use (cutting or recomposition) and up to 25–30 mg/day for bulking — the latter carrying higher suppression and hepatic risk [9]. Typical cycle lengths reported are 6–8 weeks. These figures are commonly reported, not prescribed or endorsed. Bloodwork before and after is strongly advised regardless of dose chosen [9].
Sources
- 1.MedChemExpress – Ostarine (MK-2866) pharmacology
- 2.GeneMedics – Ostarine benefits, dosage & side effects
- 3.PatriotChems – MK-2866 mechanism & research overview
- 4.MuseChem – What is Ostarine (MK-2866)?
- 5.Diamond Behavioral Health – Ostarine side effects
- 6.Swolverine – MK-2866 complete guide
- 7.Anabolic Planner – MK-2866 Ostarine compound profile
- 8.Nectac – Ostarine MK-2866 guide
- 9.Predator Nutrition – MK-2866 side effects, benefits & dosage
- 10.SarmForge – Ostarine MK-2866 product & monitoring info
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.
Other options for Ostarine· 5 offers
Same compound from different labs/brands and pack sizes. Tap a row to switch brand — the price and buy button update instantly.
This compound comes in different forms (e.g. injectable vs oral vs topical). Cost per mg is only comparable within the same form.
| Brand | Form | Strength | Pack | Price | Per mg |
|---|---|---|---|---|---|
Driada | blister-pack | 10 mg/tab | 50 tab | 48,90 € | ★€0.098/mg |
Intex Pharma | blister-pack | 10 mg/tab | 60 tab | 99,99 € | €0.167/mg |
Generic | blister-pack | 10 mg/tab | 50 tab | 104,99 € | €0.210/mg |
GenericSelected | oral-liquid | 20 mg/ml | 50 ml | 109,99 € | €0.110/mg |
Generic | bottle | 20 mg/ml | 100 ml | 149,99 € | €0.075/mg |