MK-677 and RAD-140 Stack: What the Evidence Shows on Muscle and Recovery

MK-677 and RAD-140 are stacked because they work in different ways: RAD-140 is a SARM that acts on the androgen receptor, and MK-677 raises growth hormone and IGF-1. But no study has tested them together, RAD-140 has never been tested for muscle in people, and both have documented risks. RAD-140’s only human trial, in women with advanced breast cancer, found liver enzyme rises in about half the patients. MK-677 raised blood sugar and caused swelling in trials and had a heart-failure signal in frail older adults. One published case report describes a spleen rupture in a man using both.

This page sets out what each compound is, what the evidence says about the stack, how they compare, the side effects and the mistakes people make. For each one in depth, see our RAD-140 (testolone) review and MK-677 (ibutamoren) review.

What is MK 677 and RAD 140?

SARMs (selective androgen receptor modulators) are drugs designed to act on the androgen receptor, the receptor testosterone uses, with more effect on muscle and bone than on other tissues. The FDA treats products sold as SARMs as unapproved new drugs (FDA 2025), and WADA bans them in sport (WADA 2026). RAD-140 is a SARM. MK-677 is not: it is a growth hormone secretagogue, a drug that makes the pituitary release more growth hormone (FDA 2024). People combine them hoping RAD-140 adds muscle while MK-677 adds appetite, recovery and sleep.

What is RAD 140?

RAD-140 (testolone, now named vosilasarm) is a nonsteroidal SARM first described in 2011. In rats it built muscle at low doses while largely sparing the prostate, and in young male monkeys 28 days lowered testosterone by about two-thirds (Miller 2011). Its only published human trial was a Phase 1 study in 22 women with advanced breast cancer, taking 50 to 150 mg/day: AST rose in 59% and ALT in 45% of patients, and serious liver enzyme rises occurred in 23% (LoRusso 2022). It is being tested again for breast cancer, not for muscle. No trial has measured muscle, strength or testosterone in men taking it. More in the RAD-140 review.

The older version of this page called RAD-140 “one of the most powerful and well-researched SARMs” with “fewer androgenic side effects”. With one small human trial, in cancer patients, neither description is supported.

What is MK 677?

MK-677 (ibutamoren) copies the hunger hormone ghrelin. It raises GH and IGF-1: after 12 months on 25 mg/day, GH was 1.8 times and IGF-1 1.5 times baseline in older adults. Fat-free mass rose 1.1 kg vs a 0.5 kg loss on placebo, but strength didn’t change and body fat didn’t fall (Nass 2008). In one small study, bedtime doses increased deep and REM sleep (Copinschi 1997). It has been tested in 17 human trials but never approved; the FDA lists serious safety concerns (FDA 2024). The older claims on this page that MK-677 supports fat loss and is a “safer alternative” to hormone therapy aren’t supported by those trials.

MK-677 vs RAD-140

Sources: Nass 2008, Svensson 1999, LoRusso 2022, Miller 2011, WADA 2026. Compare them on half-life, evidence and suppression with the compare tool.

Enhanced recovery with MK 677 and RAD 140?

Recovery is the most common reason people give for this stack, but it has not been measured. In MK-677 trials after hip fracture, physical function did not improve significantly despite large IGF-1 rises (Bach 2004, Adunsky 2011). The sleep effect of MK-677 comes from one study of 14 people over 1–2 weeks (Copinschi 1997). For RAD-140 there is no human recovery data at all.

Growth hormone and muscle growth

The theory is that MK-677 raises GH and IGF-1 while RAD-140 acts directly on muscle’s androgen receptors. The measured part is modest: MK-677’s extra fat-free mass (1.1 kg over a year) did not come with more strength (Nass 2008), and RAD-140’s muscle effects come from rats and monkeys (Miller 2011). Whether the two add up in people is unknown.

Natural testosterone production and PCT

RAD-140 lowered testosterone by about two-thirds in monkeys (Miller 2011), and case reports in men describe low testosterone after products that contained it along with other drugs (Chong 2024). MK-677 does not protect against that: when it was taken with another SARM, LGD-4033, testosterone still fell 62% (Cardaci 2022). See MK-677 as PCT and SARMs PCT for what the evidence on recovery covers.

Where to buy RAD 140 and MK 677

Products sold online often don’t match their labels: in a test of 44 products sold as SARMs, only 41% contained the labeled amount and 25% contained unlisted substances (Van Wagoner 2017). Whatever the source, look for a batch-specific certificate of analysis from an independent lab. Sarmguide’s current partner shop is SwissChems (our review), which sells:

➡️ RAD-140 (10 mg capsules)

➡️ MK-677 (10 mg capsules)

SwissChems also sells a value pack with RAD-140, MK-677 and YK-11. YK-11 is a lab-made steroid sold as a SARM; it has never been tested in people. See our YK-11 review before considering it.

➡️ RAD-140 + MK-677 + YK-11 value pack

These products are sold for research purposes only and are not approved medicines. The FDA has said that “research use only” labels don’t change whether a product is a drug intended for people (FDA 2025).

Potential side effects of the MK 677 and RAD 140 stack

Both compounds can raise liver enzymes, so the liver is where their risks overlap. Full details: MK-677 side effects and the stack checker.

Stacking support and supplements

“Liver support”, “joint support” and other add-ons are often sold alongside SARM stacks. A PubMed search (30 October 2026) found no study testing liver-protecting products such as TUDCA, ursodeoxycholic acid, silymarin or N-acetylcysteine against SARM or MK-677 side effects. What trial investigators relied on for MK-677 was monitoring: fasting glucose, HbA1c, liver enzymes, prolactin, lipids and blood pressure (FDA 2024). The bloodwork planner explains each marker.

Alternatives to RAD 140 and MK 677

If the goal is muscle without these risks, training and diet carry no drug risk at all. If you suspect low testosterone, a blood test and a doctor are the route to an approved treatment; see our low testosterone blood test guide. To compare other compounds by evidence and side effects, use the SARMs and peptides database.

Scientific research and studies

• The combination: no trial. One case report of spleen rupture in a user of both (Jaffry 2026).
• RAD-140: one Phase 1 trial in 22 women with breast cancer (LoRusso 2022); muscle data only from rats and monkeys (Miller 2011).
• MK-677: 17 human trials, mostly in older adults and patients; more lean mass, no strength gain, higher blood sugar (Nass 2008, FDA 2024).

Common mistakes and pitfalls

• Assuming MK-677 protects testosterone. It didn’t prevent a 62% drop when stacked with LGD-4033 (Cardaci 2022).
• Ignoring blood sugar. MK-677 raised fasting glucose and HbA1c in trials, and some participants had to lower the dose or stop (FDA 2024).
• Trusting the label. 59% of products sold as SARMs differed substantially from their labels (Van Wagoner 2017).
• Treating anecdotes as evidence. Neither compound has been tested for muscle or recovery in young people who train.
• Forgetting sport rules. Both are banned at all times by WADA (WADA 2026).