Short answer: yes. In the human trials that measured hormones, SARMs lowered testosterone. Three weeks of LGD-4033 at only 0.1–1.0 mg/day lowered total testosterone and SHBG in healthy young men, and at 1.0 mg/day free testosterone and FSH fell too. Ostarine at 1–3 mg/day lowered total testosterone by about 6–7 nmol/L over 86 days in older men. In the trials that followed people after stopping, levels came back.
Below: the numbers from each study, whether the drop is permanent, what it means for libido, erections and fertility, and how it is checked. For the evidence on every compound, see the SARMs database.
What are SARMs?
SARMs, or Selective Androgen Receptor Modulators, are a class of compounds designed to interact with the androgen receptor in a selective manner. Unlike traditional anabolic androgenic steroids, which broadly affect androgen receptors throughout the body, SARMs are intended to target specific tissues, such as muscles and bones, to promote effects like increased lean body mass and bone density.
How do SARMs work in the body?
The chemical structure of SARMs allows them to selectively bind to androgen receptors in muscle and bone cells, potentially enhancing muscle growth and strength without the adverse effects often associated with anabolic steroids, such as prostate growth. This selective action is why SARMs have garnered interest both in medical research, where they were initially studied for conditions like muscle wasting and osteoporosis, and among athletes and bodybuilders seeking performance enhancement with fewer side effects.
Do SARMs lower testosterone levels?
Yes. A SARM switches on the androgen receptor, and the brain reads that as “enough androgen”. It then sends less LH and FSH to the testes, which make less testosterone. Many SARMs also lower SHBG, the protein that carries testosterone in the blood, which lowers the total testosterone figure on a blood test.
What the studies measured
| Compound | Study | Effect on testosterone |
|---|---|---|
| LGD-4033 | 0.1, 0.3 or 1.0 mg/day for 21 days; 76 healthy men aged 21–50 (placebo-controlled) | Total testosterone and SHBG fell with dose. At 1.0 mg/day, FSH and free testosterone also fell. All back to baseline by day 56. |
| Ostarine | 1 or 3 mg/day for 86 days; older men and postmenopausal women (placebo-controlled) | Total testosterone fell 6.4 nmol/L (1 mg) and 7.4 nmol/L (3 mg) vs placebo; SHBG fell on 3 mg. Free testosterone, LH and FSH did not change significantly. |
| Ostarine | Up to 30 mg/day for 14 days; healthy men (Phase 1) | SHBG and total testosterone fell with dose; free testosterone did not change in a clinically significant way. |
| RAD-140 | Never measured in men. Young male monkeys, 28 days | Testosterone fell from about 600–800 to about 200–300 ng/dL (animal data). |
| LGD-4033 + MK-677 | One man, 10 mg LGD-4033 + 15 mg MK-677 daily for 5 weeks (case report) | Total testosterone fell 62% and free testosterone 86%; most values recovered after stopping. |
| MK-677 (not a SARM) | 8 weeks; obese men (placebo-controlled) | Total testosterone fell vs placebo, but the testosterone/SHBG ratio, LH and FSH did not change. |
Note the doses: the LGD-4033 trial tested 1 mg/day at most, a fraction of what products are usually sold at. Suppression at higher doses has not been studied in controlled trials. The chart below shows how strong the suppression evidence is for each compound in our database.
Source: Sarmguide compound database.
Do SARMs increase testosterone?
No. This is a common claim online, but no study supports it. SARMs act like an androgen at the receptor, so the body responds by making less of its own testosterone, as the trials above show. What users feel as a “boost” is the drug’s own androgenic effect, not higher natural testosterone.
The compounds that do raise a man’s own testosterone work differently. SERMs such as enclomiphene and clomiphene block estrogen feedback in the brain, so LH, FSH and testosterone go up; in healthy men, clomiphene at 50 mg/day for 30 days more than doubled testosterone. That is why they are discussed for recovery after SARMs (see SARMs PCT).
Do SARMs permanently lower testosterone?
Not in the studies we have. In the 21-day LGD-4033 trial, testosterone, SHBG and FSH were back to baseline by day 56, about five weeks after the last dose. The case report of a man on LGD-4033 plus MK-677 also showed most values recovering after he stopped.
But these studies were short and used low doses. Recovery after months of use, higher doses or several compounds together has not been studied in trials, and people differ. Persistent symptoms after stopping are a reason to see a doctor and get tested, not to wait it out.
Can SARMs cause erectile dysfunction?
Since SARMs do lower testosterone, it also leads to an increased risk of experiencing erectile dysfunction (ED). Testosterone is a crucial hormone for maintaining erectile function and libido in males. And so, when testosterone drops, as observed with SARM use, it can lead to reduced sexual desire and difficulty achieving or maintaining an erection.
Erectile dysfunction occurs when there is insufficient blood flow to the penis or when nerves and muscles involved in the process are not functioning correctly. Testosterone plays a significant role in regulating the nitric oxide pathway, which is essential for dilating blood vessels in the penis during sexual arousal. Therefore, lower testosterone, induced by substances like SARMs, can impair this process and contribute to erectile dysfunction.
Users should be cautious of these hormonal effects, which could manifest as sexual dysfunction among other issues, and consider consulting healthcare professionals before using SARMs for muscle enhancement or performance purposes.
For men with persistent low libido or ED after stopping, a doctor can check testosterone, LH and FSH and look for other causes.
Can SARMs shrink your testicles?
Unfortunately, using Selective Androgen Receptor Modulators (SARMs) can potentially shrink testicles. SARMs are often used to mimic the effects of anabolic steroids, which can affect the body’s natural hormone production. When SARMs are used, the body may reduce its own production of testosterone as it relies on the external source. This reduction can lead to testicular atrophy or shrinkage because the testes are producing less testosterone and may shrink in response.
If testicular shrinkage occurs due to SARMs use, the first and most important step is to discontinue their use. This will allow your body to start re-adjusting and potentially restore natural testosterone. Consulting a healthcare professional is crucial; they can assess your hormone levels and provide personalized advice. Doctors sometimes use SERMs, which raise LH and FSH, to restart natural production.
Follow-up visits with a healthcare provider help track recovery. Recovery can vary, and some individuals may experience a gradual return to normal testicular size and function, while others might face longer-term effects. Always seek professional guidance to navigate these issues safely.
Testicle size follows LH and FSH. In an online survey of 343 SARM users, more than half reported side effects, and smaller testicles were among the side effects reported.
Can SARMs cause gyno?
Gynecomastia, often referred to as “gyno,” is the enlargement of breast in males, and it can potentially be caused by the use of Selective Androgen Receptor Modulators (SARMs). SARMs can influence hormone levels in the body, leading to an imbalance between estrogen and testosterone. This hormonal disruption can result in increased estrogenic activity, either directly from the SARMs themselves or through indirect mechanisms. Some SARMs might have weak estrogenic effects or cause the body to convert more testosterone into estrogen, contributing to the development of gynecomastia.
Moreover, SARMs can suppress natural testosterone, creating a relative increase in estrogen levels that can stimulate breast tissue growth. If you notice symptoms such as breast tenderness, swelling, or lump formation while using SARMs, it is important to stop use and consult a healthcare professional. They can provide a proper diagnosis and recommend appropriate treatment or management strategies to address any hormonal imbalances and prevent or manage gynecomastia.
SARMs side effects
Other than affecting testosterone, SARMs do have other side effects that you need to consider before deciding to take them. Their side effects can be categorized into two groups: long-term and short-term. Let’s begin discussing the latter.
Short term
Short-term side effects of SARMs typically manifest relatively quickly after taking them and may vary depending on the specific compound and dosage. These include the following:
- Nausea
- Fatigue
- Sleep disturbances or insomnia
- Dizziness
- Skin rashes or irritation
- Changes in appetite (may suppress or increase appetite)
- Mood swings
Long term
The FDA has not approved any SARM. Long-term problems reported with SARM products include:
- Heart attacks
- Hair loss
- Strokes
- Liver damage and acute liver failure
- Sexual dysfunction
- Infertility
- Decreased libido
- Testicular shrinkage
Additionally, the World Anti-Doping Agency (WADA) has banned the use of SARMs in sports due to their ability to mimic the effects of testosterone and anabolic steroids. And so, consumers are urged to consult healthcare professionals before using products claiming to increase muscle mass or enhance athletic performance, given the significant risks associated with these unapproved substances.
How suppression is checked
Suppression is a lab finding, so it is measured with blood tests. The trials above tracked total and free testosterone, LH, FSH and SHBG; lipids (HDL fell in both the ostarine and LGD-4033 trials) and liver enzymes are usually checked too. Our SARMs bloodwork guide explains each marker, and the PCT and bloodwork planner shows what the evidence says for each compound.
Monitor for side effects
Watch for symptoms of low testosterone (low libido, erection problems, low mood, fatigue) and of liver trouble (dark urine, yellow eyes, itching). Case reports describe hormonal problems, liver toxicity, and heart problems with SARM products. Any of these symptoms are a reason to stop and see a doctor. Regular consultation with healthcare professionals can provide valuable insights and guidance to help navigate these considerations effectively.
Blood tests
When using SARMs, it’s important to get regular blood tests to keep your hormones and liver in check. You can do this through private tests at a clinic or by visiting a specialized IPED clinic. As you may already know, SARMs can affect hormone levels, which might cause changes in mood, sex drive, or menstrual cycles for women. They can also harm the liver without showing symptoms, so regular tests are crucial to catch any issues early. These check-ups help you stay on top of your health and manage any risks from using SARMs effectively.
Restoring testosterone: what the options are
Most of the trial data on recovery come from SERMs, which raise LH, FSH and testosterone. They are prescription drugs in most countries, and they have their own side effects. Compare them on our SARMs PCT page, the Nolvadex (tamoxifen) and Clomid pages, and in the comparison enclomiphene vs clomiphene.
Conclusion
SARMs lower testosterone. The trials that measured it found drops in total testosterone and SHBG at low doses within weeks, and LGD-4033 lowered free testosterone and FSH too. In those short trials, levels recovered after stopping; nobody has studied long or high-dose use. They do not raise natural testosterone. If you want to know where your hormones stand, a blood test is the only reliable answer.
Related: SARMs vs testosterone · SARMs vs TRT · RAD-140 suppression · ostarine suppression
Frequently asked questions
Do SARMs lower testosterone?
YesEvidence: Trial
In trials, LGD-4033 at 0.1–1.0 mg/day and ostarine at 1–3 mg/day lowered total testosterone and SHBG. At 1.0 mg/day LGD-4033 also lowered free testosterone and FSH within 21 days.
Do SARMs increase testosterone?
NoEvidence: Trial
No study supports it: SARMs act on the androgen receptor, so the body makes less of its own testosterone. Drugs that raise natural testosterone, such as enclomiphene and clomiphene, are SERMs.
Do SARMs permanently lower testosterone?
Not in short trialsEvidence: Trial
In the 21-day LGD-4033 trial, hormones were back to baseline by day 56. Recovery after long, high-dose or combined use has not been studied.
Does ostarine shut down testosterone?
Lowers it partlyEvidence: Trial
In older men on 1–3 mg/day for 86 days, total testosterone fell 6.4–7.4 nmol/L vs placebo, while free testosterone, LH and FSH did not change significantly. That is partial suppression at those doses, not a full shutdown.
Does RAD-140 lower testosterone?
Likely; never measured in menEvidence: Animal
It has never been measured in men. In young male monkeys, 28 days of RAD-140 cut testosterone from about 600–800 to about 200–300 ng/dL.
Does YK-11 lower testosterone?
Unknown; no human studiesEvidence: User reports
There are no human studies of YK-11. It acts on the androgen receptor, and users commonly report suppression.
Do SARMs cause erectile dysfunction?
They canEvidence: Human data
Through lower testosterone, which reduces libido and can make erections harder to get and keep. Persistent low libido or ED after stopping is a reason to see a doctor.
Can SARMs shrink your testicles?
Yes, they canEvidence: User reports
Lower LH and FSH mean the testes make less testosterone, and they can shrink. In an online survey of 343 SARM users, smaller testicles were among the side effects reported.
Is enclomiphene a SARM?
No, it is a SERMEvidence: Human data
Enclomiphene is a selective estrogen receptor modulator: it blocks estrogen feedback in the brain, so LH, FSH and testosterone rise. SARMs do the opposite to natural testosterone.
Can you take SARMs while on TRT?
Not studiedEvidence: Limited
The combination has not been studied. On TRT, natural production is already suppressed, and a SARM adds its own risks, such as lower HDL and liver effects.
Sources
- The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men
- The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial
- EMERALD study protocol (ISRCTN12213700, University of Liverpool, version 6.0, 2021): a window of opportunity study of enobosarm in ER+/AR+ early breast cancer
- Design, Synthesis, and Preclinical Characterization of the Selective Androgen Receptor Modulator (SARM) RAD140
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
- Discrepancy between serum leptin values and total body fat in response to the oral growth hormone secretagogue MK-677
- Adverse effects and potential benefits among selective androgen receptor modulators users: a cross-sectional survey
- Hypothalamic-Pituitary-Testicular Axis Effects and Urinary Detection Following Clomiphene Administration in Males
- Oral enclomiphene citrate raises testosterone and preserves sperm counts in obese hypogonadal men, unlike topical testosterone: restoration instead of replacement
- FDA: Certain bodybuilding products put consumers at risk for heart attack, stroke, serious liver damage and more (content current as of 2 December 2025)