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 consultation.

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 while increasing:

  • Testicular size
  • Energy
  • Quality of mood
  • Retention of gains
  • 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), so 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 while 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 than 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 returns to normal several weeks post-cycle (even without a PCT).

Disclosure: We do not accept any form of advertising on Inside Bodybuilding. We monetize our practice via doctor consultations and carefully chosen supplement recommendations, which have given our patients excellent results.

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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 20 mg/day, which is a standard dosed Ostarine cycle.

Another male reported that after taking 20–30 mg/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 5 mg/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 10 mg/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 SARM 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 20 mg/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 40 mg/day of Nolvadex for 4 weeks, although this is an aggressive PCT and unnecessary for most Ostarine users. If a user is taking 20 mg/day of Nolvadex and endogenous levels are not improving after 2 weeks, an increased dose of 40 mg/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

  1. Nolvadex: 40 mg/day (20 mg x 2, taken continuously for 45 days)
  2. Clomid: 100 mg/day (50 mg x 2, taken continuously for 30 days)
  3. 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
  • 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 or 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 and then receiving blood work stating that they are in fact hypogonadal.

These individuals have a normal sexual desire, high strength in the gym, and 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 or unbound type of testosterone that the body actually utilizes to synthesize new muscle tissue.



Our experience, combined with other anecdotal reports, suggests 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:

  1. Temporary headaches
  2. Hot flashes
  3. Fatigue
  4. 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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