Ostarine (MK-2866)

What is Ostarine (MK-2866)?

The mildest and most studied SARM. Selective androgen receptor modulator with relatively lower suppression.

How Ostarine (MK-2866) works

Selectively activates androgen receptors in muscle and bone with reduced prostate activity versus testosterone.

Benefits & uses

• Lean muscle gain
• Muscle preservation in a deficit (cutting)
• Milder/less suppressive than other SARMs
• Bone/joint support (studied for cachexia)
• Lean muscle
• Muscle preservation (cutting)
• Milder SARM

Common uses: Muscle preservation, recomposition, recovery, mild strength/mass gains.

Ostarine (MK-2866) dosage

Ostarine (MK-2866) half-life

Ostarine (MK-2866) side effects

Mild suppression, lipid changes, occasional liver enzyme elevation.

Warnings & monitoring

• Requires bloodwork (testosterone, lipids) + medical guidance
• Still suppresses — longer/higher runs need PCT
• FDA-warned / WADA-banned / gray-market purity unreliable
• Not approved for human use
• Requires bloodwork + medical guidance
• Suppressive at higher/longer doses — PCT
• FDA-warned / WADA-banned / gray-market

Preparation & storage

Ostarine (MK-2866) interactions

• with GW501516

  Caution · moderate

  Ostarine is relatively mild; GW501516 is a PPARδ agonist associated with carcinogenicity in animal studies. Human risk unknown but significant enough to warrant caution.

  Timing: GW501516 (Cardarine) has been discontinued in research due to cancer findings in animal studies

• with LGD-4033

  Caution · mild

  Combining two SARMs increases suppression beyond either alone. Ostarine is milder than LGD — this stack is more manageable than RAD+LGD but still requires bloodwork monitoring and PCT consideration.

  Timing: Use Ostarine 10–15 mg with LGD 5 mg; monitor testosterone levels

• with Cardarine

  Compatible

  A popular mild body recomposition stack. Ostarine preserves muscle during a cut while Cardarine boosts fat oxidation and endurance. Minimal androgenic side effects at these doses.

  Timing: Daily; Cardarine 20 mg, Ostarine 10–25 mg

• with Cardarine

  Compatible

  Cardarine boosts endurance and fat oxidation while Ostarine preserves lean mass on a deficit — a well-studied recomp stack.

  Timing: Both daily during recomp/cut cycles, 8–12 weeks

• with Enclomiphene

  Compatible

  Mild SARM suppression can be supported with low-dose enclomiphene without crashing E2 like Clomid sometimes does.

  Timing: Enclomiphene 12.5mg daily during/after Ostarine to support LH

• with MK-677

  Compatible

  A popular entry-level recomp stack. Ostarine preserves lean mass and strength while MK-677 boosts GH/IGF-1. Minimal suppression from Ostarine at low doses.

  Timing: Both can be run concurrently; MK-677 year-round, Ostarine 8–12 week cycles

• with MK-677

  Compatible

  MK-677 elevates GH/IGF-1 while Ostarine activates androgen receptors selectively — a steady, non-suppressive lean-gain stack.

  Timing: MK-677 nightly, Ostarine morning, 12–16 weeks

• with S4 (Andarine)

  Compatible · low

  S4 (Andarine) stacks well with Ostarine for cutting or recomposition. S4 provides anabolic hardening effects; Ostarine preserves muscle in a deficit. Vision side effects from S4 are dose-dependent.

  Timing: Run concurrently; S4 may cause visual disturbances at higher doses

Commonly stacked with