Do SARMs Increase or Decrease Libido? What the Evidence Shows

Short answer: SARMs can raise libido early in a cycle and lower it later, but no study has measured libido as an outcome. What trials did measure is the mechanism: SARMs activate the androgen receptor while lowering your own testosterone. LGD-4033 lowered total and free testosterone at 1 mg a day in 21 days (Basaria 2013), and ostarine lowered total testosterone in older men at 1–3 mg a day (Dalton 2011). Users commonly describe higher sex drive on cycle and low libido toward the end or after it, as their own testosterone stays low.

How Do SARMs Work in the Body?

SARMs bind the androgen receptor, the same receptor testosterone uses, with the aim of building muscle and bone with less effect on other tissues. While they activate the receptor, the brain sees more androgen signal and turns down its own signal (LH and FSH) to the testes, so natural testosterone falls. This was measured in trials: with LGD-4033, total testosterone, SHBG and, at 1 mg, free testosterone and FSH fell, and all recovered by day 56 (Basaria 2013).

Libido depends partly on androgen signaling, so the effect of a SARM on sex drive can change over a cycle: the SARM itself may support it, while falling natural testosterone works against it, especially after you stop. No study has measured libido directly.

What SARMs Can Decrease Libido?

Lower libido is most often reported with the more suppressive compounds:

• LGD-4033: suppression measured from 0.1 mg a day; the original author of our 8-week LGD-4033 log reported lower libido in weeks 7–8 at 2.5 mg a day.
• S-23: strongly suppressed LH in rats and was developed as a male contraceptive (Jones 2009).
• YK11: never measured, but users nearly always run a PCT after it.
• RAD-140: cut testosterone by about two-thirds in monkeys (Miller 2011).

In a documented case, a man taking LGD-4033 with MK-677 had total testosterone down 62% and free testosterone down 86% after 5 weeks (Cardaci 2022).

What SARMs Can Increase Libido?

Users often report higher libido during a cycle with RAD-140 and andarine, and sometimes MK-677. These are anecdotal reports; no study has tested any SARM for libido. Note that RAD-140, the compound most often named, is also one of the more suppressive in animal data, so a boost on cycle can turn into a drop after it. MK-677 is not a SARM and does not raise testosterone; in obese men it lowered total testosterone vs placebo (Svensson 1999).

Ostarine is often suggested as the option least likely to affect libido. It is milder in the sense that free testosterone, LH and FSH did not change significantly at 1–3 mg a day in its trial, but total testosterone did fall, and user doses are much higher (Dalton 2011).

Ways to Safeguard Your Libido While Taking SARMs

• Get bloodwork. Total and free testosterone, LH, FSH and estradiol before, at the end of and a few weeks after a cycle show whether low libido is hormonal. The PCT and bloodwork planner lists the markers.
• Lower doses, single compounds. Suppression grew with dose in the LGD-4033 trial, and stacks add suppression from each compound.
• Know the recovery data. After 21 days of LGD-4033 at up to 1 mg, hormones recovered within five weeks; recovery after longer, higher-dose use hasn’t been studied. PCT options and what studies show about them are in SARMs PCT.
• See a doctor if low libido or erectile problems persist after stopping; persistently low testosterone is a medical issue, and treatment options such as TRT need medical supervision.

Final Thoughts

SARMs affect libido through hormones: they act on the androgen receptor while suppressing your own testosterone. Users report a boost on cycle with some compounds and a drop toward the end and after, most with suppressive ones like LGD-4033, S-23, YK11 and RAD-140. Nothing about libido has been measured directly in studies, so bloodwork is the way to know what is happening. Compare compounds’ suppression data in the SARMs database.