The side effects of SARMs best documented in human trials are lower testosterone and SHBG, lower HDL (“good”) cholesterol and rises in liver enzymes. Case reports add serious liver injury with jaundice, and heart inflammation after RAD-140. Compounds sold next to SARMs carry their own risks: MK-677 raises appetite, fluid retention and blood sugar, and cardarine caused cancer in animal studies. Below is every finding in our database, by body system, with its evidence level and source.
Side effects by body system
| Body system | What was found | Evidence | Read more |
|---|---|---|---|
| Testosterone and fertility hormones | LGD-4033: total testosterone and SHBG fell with dose over 21 days; FSH and free testosterone fell at 1 mg (Basaria 2013). Ostarine: total testosterone fell 6.4 to 7.4 nmol/L vs placebo in older men, with no significant change in free testosterone, LH or FSH (Dalton 2011). RAD-140: testosterone fell by about two-thirds in monkeys; it has not been measured in men (Miller 2011). MK-677: lower total testosterone in obese men, with LH and FSH unchanged (Svensson 1999). S-23: in male rats given estradiol as well, sperm production stopped in 4 of 6 animals (Jones 2009). | Trial; animal (RAD-140) | Suppression, do SARMs lower testosterone?, testicles |
| Cholesterol | Ostarine: HDL fell 17% (1 mg) and 27% (3 mg) over 86 days; LDL did not change (Dalton 2011). LGD-4033: HDL and triglycerides fell with dose and returned to baseline after stopping (Basaria 2013). Clomiphene: HDL fell vs placebo in obese men (Soares 2018). Case report: an abnormal lipid panel, raised liver enzymes and suppressed hormones in a weightlifter using LGD-4033 with S-23, all back to baseline after stopping (Bull Natl Res Cent 2023). | Trial; case report | Ostarine, LGD-4033 |
| Liver | Trials: ALT rose with dose in a 14-day ostarine study in healthy men (EMERALD protocol), and 3 to 4% of women with breast cancer on 9 to 18 mg had serious liver enzyme rises (Palmieri 2024). In RAD-140’s Phase 1 trial, AST rose in 59% and ALT in 45% of patients (LoRusso 2022). Case reports: jaundice and cholestatic liver injury in users of ostarine (Mertens 2024), LGD-4033 (Barbara 2020) and RAD-140 (Dao 2026), and in a Marine who used LGD-4033, RAD-140 and YK-11 together (Lee 2023); a 2026 review calls this the main serious harm (Adolf 2026). SR9009: acute liver failure needing an emergency transplant in a 17-year-old (Shams Bin Shaheen 2026). | Trial; case report | Are SARMs liver toxic? |
| Blood sugar | MK-677: fasting glucose rose about 5 mg/dL and insulin sensitivity fell over 12 months (Nass 2008); in an Alzheimer’s trial, glucose rose in 15.4% vs 4.6% on placebo and HbA1c in 11.1% vs 1.4% (FDA 2024). Tesamorelin: HbA1c of 6.5% or more in 5% vs 1% (label). Anastrozole: lower insulin sensitivity in healthy men (Gibb 2016). Case report: blood sugar of 558 mg/dL, needing insulin, in a bodybuilder after 3 months of RAD-140, andarine and MK-677 (Sotorník 2022). | Trial; case report | MK-677 side effects |
| Heart, blood pressure and clots | MK-677: in a hip-fracture trial, heart failure occurred in 4 of 62 patients vs 1 of 61 on placebo and the trial stopped early; systolic blood pressure rose about 12 to 16 mmHg (FDA 2024). RAD-140: case reports of myopericarditis, including a 16-year-old after his first dose (Schwartzman 2024), and of heart failure (Skorupski 2024). CJC-1295: FDA cites faster heart rate and a vasodilatory reaction (FDA). Enclomiphene: four thromboembolic events in trials (blood clots and one fatal stroke), all in men with other risk factors (EMA 2018). YK-11: FDA tested a product after a user had a stroke and found YK-11 plus an undeclared steroid (FDA). | Trial; case report; regulator review | SARMs and blood pressure |
| Fluid, joints and muscles | MK-677: leg swelling in 19 of 43 people vs 6 of 22 on placebo, and short-lived muscle pain in 14 of 43 vs 2 of 22 (FDA 2024). Tesamorelin: joint pain 13% vs 11% and swelling 6% vs 2% (label). Ostarine with cardarine: severe muscle breakdown in one case report (Kintz 2021). | Trial; case report | MK-677 side effects |
| Breast tissue (gynecomastia) | One case report: breast growth and low testosterone after supplements labeled as RAD-140, MK-677 and cardarine that also contained undeclared testosterone, estradiol and growth hormone; it resolved after stopping (Chong 2024). MK-677 raised prolactin about 23%, within the normal range (Chapman 1996). No SARM trial in our database reported gynecomastia. | Case report; trial | Do SARMs cause gyno?, MK-677 and gyno |
| Cancer signals | Cardarine: tumors in many tissues in rats at all doses and stomach cancers in mice at all doses in two-year studies (Toxicologist 2009); more and larger intestinal polyps in polyp-prone mice (Gupta 2004). MK-677: no trial has shown that it causes cancer; FDA notes that drugs raising GH and IGF-1 carry tumor warnings (FDA 2024). | Animal; not established in humans | SARMs and cancer |
| Vision, mood and brain | Clomiphene: the label warns of visual symptoms that rise with dose and duration (label); among 120 men on it for over 3 years, 5 reported mood changes and 3 blurred vision (Krzastek 2019). Enclomiphene: blurred vision 0.5% vs 0% (EMA 2018). Tamoxifen: loss of libido and impotence led some men to stop (label). YK-11: oxidative stress and impaired memory consolidation in 5-week rat studies (Dahleh 2024). | Trial; observational; animal | SERMs explained, SARMs and the brain |
| What is in the product | Of 44 products sold online as SARMs, only 52% contained a SARM, 25% held substances not on the label and 41% matched the labeled amount (Van Wagoner 2017). FDA warns that different molecules are sold under the name TB-500 (FDA 2026). A 2024 review of FDA adverse event reports found cases naming YK-11 and andarine, including liver failure and stroke (Leciejewska 2024). | Lab analysis; regulator review | How to read a COA |
Hair loss, acne and kidney problems are common questions, but the trials in our database did not report them for ostarine, LGD-4033 or RAD-140. What is known is in our guides on SARMs and hair loss, acne and kidney damage.
Testosterone suppression by compound
Source: Sarmguide compound database.
How to read the evidence levels
| Label | What it means | How much weight it carries |
|---|---|---|
| Trial | A controlled study in people, often randomized against placebo (NCI) | The strongest evidence for cause and effect, at the doses and in the people studied |
| Observational | People followed or measured without being assigned a treatment (NCI) | Shows patterns, not proof of cause |
| Case report | A detailed report on one patient (NCI) | A warning sign; cannot show how often something happens |
| Animal | Studies in animals or cells (NCI) | May not apply to people |
| Regulator review | A finding or warning from the FDA, EMA or another regulator | Based on the regulator’s review of all data it holds |
| Lab analysis | Tests of products bought on the market | Shows what is actually sold, not effects in people |
Why the trials understate the risk
- Trials were short (weeks to a few months), used low, measured doses and monitored people closely.
- The serious harms appear mostly in case reports of higher-dose, stacked and unmonitored use; in almost all of them the product was never analyzed, so undeclared steroids cannot be ruled out (Adolf 2026).
- Combinations have not been tested in trials. One man who took LGD-4033 with MK-677 for 5 weeks had a 62% drop in total testosterone, a 36% drop in HDL and a 205% rise in ALT (Cardaci 2022). Check overlaps with the stack checker.
Do side effects go away after stopping?
Often, but not always quickly. In the LGD-4033 trial, hormones and lipids were back to baseline by day 56, five weeks after the last dose (Basaria 2013). With MK-677, IGF-1 returned to baseline a month after stopping (Nass 2008). Most people with SARM-related liver injury in case reports recovered over weeks to months; in one ostarine case bilirubin took about six months to return to normal (Mertens 2024), and a 2026 RAD-140 case needed intensive care (Dao 2026).
Blood markers the studies tracked
- SARMs: total and free testosterone, LH and FSH, SHBG, lipid panel (HDL, LDL, triglycerides), liver enzymes (ALT, AST) and bilirubin; PSA and hematocrit for LGD-4033.
- MK-677: IGF-1, fasting glucose and insulin, HbA1c, liver enzymes, prolactin and lipids.
- Cardarine: lipid panel, liver enzymes, fasting glucose and insulin, and creatine kinase.
These are the markers the studies monitored, listed on each fact sheet. A doctor can order and interpret them; our SARMs bloodwork guide explains each marker.
Side effects of each compound
- MK-677 side effects and the MK-677 fact sheet
- Ostarine, LGD-4033 and RAD-140
- YK-11, S-23, andarine (S4), RAD-150, AC-262,536 and ACP-105
- Cardarine and SR9009
- Enclomiphene, clomiphene, tamoxifen (Nolvadex) and anastrozole
- BPC-157, TB-500, ipamorelin, CJC-1295 and tesamorelin