Ostarine PCT: Optional or Essential?

Dr George TouliatosDisclaimer: SARMs are only to be used for research purposes, as they are non-FDA approved compounds and thus may cause adverse effects. If you have any questions or concerns, Dr. Touliatos is currently available for consultations.

Ostarine (Mk-2866) is a mild SARM, often utilized by beginners to build lean muscle and burn fat.

Post-cycle therapies are often taken by bodybuilders after taking SARMs or anabolic steroids, in a bid to resurrect decreased endogenous testosterone levels; whilst increasing testicular size, energy, quality of mood, retention of gains and libido.

Due to Ostarine being a well-tolerated SARM by both men and women, a PCT is considered by some to be unnecessary. However, we regularly find endogenous testosterone levels drop during any SARM cycle (including Ostarine), thus it is wise for users to have an effective PCT protocol ready.

Ostarine Lowers Endogenous Testosterone

Everyone is different when taking SARMs, thus despite Ostarine’s renowned mild nature, some users can experience moderate side effects from it.

If endogenous levels drop significantly, bodybuilders will shift into a catabolic state post-cycle; whilst experiencing worsened mood, less energy and reduced libido.

Note: Individuals who have never taken SARMs, pro-hormones or anabolic steroids may be more susceptible to bigger drops in endogenous testosterone when taking Ostarine, vs someone whose body is already accustomed to PEDs.

As users can respond differently to Ostarine, we recommended getting blood work completed before, during and after a cycle. Depending on how acute or severe endogenous levels fluctuate, such test results will give an insight into whether a PCT is necessary.

It is worth noting that if a user does experience modest drops in endogenous testosterone from Ostarine, such damage to the HPTA (hypothalamic-pituitary-testicular axis) typically regulates back to normal several weeks post-cycle (even without a PCT).

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How Suppressive is Ostarine?

One user reported a dramatic drop in testosterone levels from Ostarine, recording 911 ng/dL pre-cycle and 113 ng/dL post-cycle (1). Medically, we diagnose less than 300 ng/dL as hypogonadism. This was following a 10-week cycle at 20mg/day, which is a standard dosed Ostarine cycle.

Another male reported that after taking 20-30mg/day of Ostarine for 2 months, his testosterone levels dropped from approximately 600 ng/dL to 200 ng/dL (2).

Another report included a man’s testosterone dropping from 665.70 ng/dL to 207.49 ng/dL after 32 days on a small dosage of 5mg/day (3).

A 23-year-old male also noticed quick suppression on Ostarine, with his testosterone dropping to 137 ng/dL after 18 days on 10mg/day (4).

There seems to be a common consensus that Ostarine is not excessively suppressive. However, we have vast anecdotal evidence of numerous users experiencing significant suppression (60-70%) — even when taking modest doses, and purchasing from well-established SARMs manufacturers.

Ostarine PCT

For users who are experiencing moderate suppression (30-50%) during their cycle, they can proceed with the following protocol, accelerating HPTA recovery.

Moderate PCT

  • Week 1-4: Nolvadex 20mg/day

Users are advised to start taking Nolvadex immediately after cycle cessation, with their testosterone levels set to recover within 30 days.

Nolvadex is a SERM (selective estrogen receptor modulator), and thus, by inhibiting the effects of estrogen, higher levels of LH are produced by the pituitary gland. Consequently, this has a stimulative effect on endogenous testosterone levels, raising them back to normal levels.

Note: In harsher cases (60-70% drops in testosterone), users may opt for 40mg/day of Nolvadex for 4 weeks, although this is an aggressive PCT and unnecessary for most Ostarine-users. If a user is taking 20mg/day of Nolvadex and endogenous levels are not improving after 2 weeks, an increased dose of 40mg/day will be beneficial.

If users have taken Ostarine in a stack containing other suppressive SARMs, they can add Clomid (clomiphene) and hCG to their PCT stack for extra potency — alongside Nolvadex.

Clomid stimulates GnRH (gonadotropin releasing hormone), which increases LH (luteinizing hormone) via the pituitary gland; effectively increasing natural testosterone production.

HCG (human chorionic gonadotropin) serves as an analogue of LH (luteinizing hormone), increasing testosterone, spermatogenesis and testicular hypertrophy (5).

Aggressive PCT

  • Nolvadex—40mg/day (20mg x 2, taken continuously for 45 days)
  • Clomid–100mg/day (50mg x 2, taken continuously for 30 days)
  • HCG—2000 IU (taken every other day for 20 days)

Note: We find the above PCT to be optimal for users who are severely shut down (>70% decreased testosterone), and are experiencing negative side effects, such as depression, lethargy and no libido.

The above PCT protocol was designed by Dr. Michael Scally, a hormone replacement specialist, who administered this trio to 19 hypogonadal men in a clinical trial. He successfully restored normal testosterone function in 100% of the men within 45 days.

This trio of medications has also been used by our patients after harsh steroid cycles to kick-start their natural androgen production.

How to Prevent Drops in Endogenous Testosterone on Ostarine

Some bodybuilders may take a natural testosterone booster during their Ostarine cycle to counter drops in endogenous testosterone.

Thus, by the time a user stops taking Ostarine, testosterone levels are more likely to remain within a normal range.

Users should look to use natural testosterone boosters, ideally combining several of the following ingredients: d-aspartic acid, ashwagandha, ginseng, zinc, and fenugreek. 

However, if users are genetically predisposed to low testosterone from interactions with Ostarine, natural testosterone boosters are unlikely to prevent notable declines in testosterone. However, they are recommended as a safe/no-risk measure to prevent excessive drops in testosterone.

Low Testosterone, No Problem

Low total testosterone levels may not even be an issue for Ostarine-users. Some Ostarine-users have reported feeling normal post-cycle, to then receive blood work stating that they are in fact hypogonadal.

These individuals have a normal sex drive, high strength in the gym, positive energy and mood.

Such a situation may be indicative of low total testosterone levels, but normal free testosterone levels.

In such an instance, a PCT may not be required, as free testosterone is the most important score; being the active/unbound type of testosterone that the body actually utilizes to synthesize new muscle tissue.


Our experience, combined with other anecdotal reports, suggest that Ostarine may be more suppressive than first thought; with 60-70% reductions in total testosterone being somewhat common.

If a testosterone booster isn’t used on-cycle, to counter decreases in serum testosterone, Nolvadex, Clomid and hCG can be taken to accelerate HPTA recovery (6,7,8).

However, such medications should only be considered if suppression is significant (below 300 ng/dL); as SERMs can present risks of side effects themselves — such as temporary headaches, hot flashes, fatigue and dizziness.

Generally, a user’s decision regarding whether to run a PCT should be based on how they feel. If their testosterone is low but they feel fine, a PCT may not be needed. Especially as Ostarine-users often retain all of their gains post-cycle; with testosterone levels commonly returning within several weeks (even without a PCT). However, if testosterone levels have crashed and the person is not feeling well, a PCT should be considered.

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