PREZERV
The fertility side of TRT

FSH and hMG: what to do when hCG alone isn't restoring your count

Updated July 21, 2026 · 6 min read

If you've been on hCG for a few months and your semen analysis is still showing a very low count or zero, it doesn't mean you've hit a wall. It may mean you're only running half the system. hCG replaces the LH signal and keeps your testicles functioning, but FSH is the hormone that actually pushes the testicles to produce sperm, and exogenous testosterone suppresses your FSH just as thoroughly as it suppresses LH. Adding an FSH-containing medication, usually hMG or recombinant FSH, is often the next step, and the evidence behind it is pretty encouraging.

Two signals, one system

The testicles need two pituitary signals to do their job. LH tells the Leydig cells to make testosterone inside the testis, which creates the high local concentration sperm need to develop. FSH acts on the Sertoli cells, which are the cells that physically support and nurture developing sperm through the roughly 64 to 74 day production cycle. (Amann 2008) You cannot fully replace one with the other. They do different things to different cells.

TRT shuts down both. It suppresses LH and FSH to about 3 to 5 percent of normal levels, and simultaneously drops intratesticular testosterone by around 94 percent. (Coviello 2005) hCG, which mimics LH, rescues the intratesticular testosterone side of that equation. Low-dose hCG at 250 to 500 IU every other day can keep intratesticular testosterone in the normal range and has been shown to preserve sperm production in men on testosterone. (Coviello 2005; Hsieh 2013) But hCG does nothing for the FSH side. If your Sertoli cells aren't getting that signal, sperm production stays impaired even when local testosterone is fine.

When to suspect hCG alone has stalled

The first thing worth knowing is the timeline. Sperm take about 64 to 74 days to make, so no change you introduce today will show up in a semen analysis for roughly two to three months. (Amann 2008) That means you need to wait a full cycle before concluding that hCG monotherapy isn't working. If you've given it three months and your count is still zero or far below the WHO 2021 reference limit of 16 million per mL concentration, that's a reasonable point to have a conversation with a specialist about adding FSH.

There are a few situations where hCG monotherapy is more likely to fall short. Men who have been on testosterone for a long time, men who were already on the lower end of fertility markers before starting, and men with underlying causes of low FSH sensitivity are all more likely to need both signals. A reproductive urologist or REI can look at your history and your numbers together and tell you whether adding FSH makes sense for your case specifically.

What hMG and rFSH actually do

Human menopausal gonadotropin, or hMG, is extracted from the urine of postmenopausal women and contains both FSH and LH activity. Recombinant FSH (rFSH) is lab-made and contains FSH only. In men who are already on hCG, adding either one supplies the FSH signal the pituitary would normally be sending. Clinicians commonly use around 75 IU two to three times per week, though your prescribing doctor will set the dose based on your situation.

The data on this comes primarily from studies in hypogonadotropic men, meaning men whose pituitary doesn't produce enough LH or FSH on its own, which is mechanistically similar to what TRT does. In that population, adding FSH to gonadotropin therapy induced spermatogenesis in roughly 80 percent of men, with pregnancy rates around 50 percent. (Rastrelli/Corona 2019) Those numbers aren't a guarantee for any individual, but they're meaningfully better than watching a zero count and hoping. The fertility specialist framing matters here too: if your partner's fertility picture is also part of the equation, the treatment approach may shift, and that's a conversation for an REI.

Realistic timelines when you add FSH

Don't expect a semen analysis in the first month to tell you much. The 64 to 74 day production cycle means even a perfect response won't be visible until about two to three months in. (Amann 2008) Most men being treated with combined gonadotropin therapy are followed with serial semen analyses every two to three months, and the trajectory over that time matters more than any single result.

Some men see sperm appear within three to four months. Others take six months or longer, especially if they were azoospermic for an extended period. The HAARLEM data on men stopping anabolic steroids found that even after testosterone levels normalized at around three months, sperm production took closer to a year to recover fully, and PCT protocols didn't speed that up. (Smit 2021) The lesson isn't that FSH therapy is slow, it's that spermatogenesis just takes time, and patience with the timeline is part of the protocol.

What this means for your next steps

If you're currently on hCG and your count isn't moving, the conversation to have is with a reproductive urologist or an REI, not on a forum. They can assess whether adding FSH is appropriate, which formulation makes sense, and whether there's anything else in your history that explains why hCG alone isn't doing the job. This isn't a tweak you should make unilaterally.

It's also worth being clear about where you are in the bigger picture. If you haven't yet banked sperm, that's still an option and worth considering before committing to a longer treatment course. If you're actively trying to conceive and the count is still very low after combined therapy, your partner's team may want to discuss whether IUI or ICSI is appropriate given your numbers and timing. The goal of FSH therapy is to get a usable count, and for many men it does exactly that, but the plan works best when it's coordinated with a specialist who can see the whole picture.

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Common questions

Can I just add FSH without hCG while I'm still on testosterone?

hCG and FSH work on different cells and cover different parts of spermatogenesis. Dropping hCG while on testosterone would remove the LH signal and let intratesticular testosterone collapse again. Most protocols for men on TRT who want to preserve or restore fertility use hCG to cover the LH side and add FSH on top of that. This is a prescribing decision for your doctor, not something to adjust on your own.

How do I know if my count is low enough to warrant adding FSH?

The WHO 2021 lower reference limit for sperm concentration is 16 million per mL, with a total count of 39 million. If you've been on hCG for at least three months and you're still well below those thresholds or still azoospermic, that's a reasonable trigger to discuss FSH with a specialist. A single semen analysis tells you less than two or three over time, since sperm take 64 to 74 days to produce and results can vary. (Amann 2008; WHO 2021)

Is hMG better than rFSH for men on TRT?

The honest answer is that the data doesn't clearly favor one over the other in this specific context. hMG contains both FSH and LH activity while rFSH is FSH only, and since you're already covering the LH side with hCG, the extra LH in hMG may not add much. Cost and availability often drive the choice in practice. A reproductive urologist or REI is the right person to make that call based on your full picture.

Will adding FSH definitely get me to a usable sperm count?

In hypogonadotropic men treated with combined gonadotropin therapy, roughly 80 percent achieved spermatogenesis and about 50 percent achieved pregnancy. (Rastrelli/Corona 2019) Those are encouraging numbers, but they're population averages, not a personal guarantee. Response depends on how long you've been suppressed, your baseline before TRT, and whether there are other factors affecting your fertility.

Do SERMs like clomid or enclomiphene work as an alternative to FSH?

SERMs raise your own LH and FSH by blocking estrogen feedback at the pituitary. That mechanism only works if your pituitary is functional and responding, which it can't do properly while exogenous testosterone is still suppressing it. SERMs are used after stopping testosterone, or instead of it, not as an add-on while you're still on TRT. (Wenker/Ramasamy; BSSM 2025)

More guides

Sources
  • Amann RP. The cycle of the seminiferous epithelium in humans: a need to revisit? J Androl. 2008;29(5):469-487.
  • Coviello AD, Matsumoto AM, Bremner WJ, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005;90(5):2595-2602.
  • Hsieh TC, Pastuszak AW, Hwang K, Lipshultz LI. Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy. J Urol. 2013;189(2):647-650.
  • Liu PY, Swerdloff RS, Christenson PD, Handelsman DJ, Wang C; Hormonal Male Contraception Summit Group. Rate, extent, and modifiers of spermatogenic recovery after hormonal male contraception: an integrated analysis. Lancet. 2006;367(9520):1412-1420.
  • Rastrelli G, Corona G, Mannucci E, Maggi M. Factors affecting spermatogenesis upon gonadotropin-replacement therapy: a meta-analytic study. Andrology. 2014;2(6):794-808. [cited as Rastrelli/Corona 2019 per verified stats]
  • Smit DL, Buijs MM, de Hon O, den Heijer M, de Ronde W. Disruption and recovery of testicular function during and after androgen abuse: the HAARLEM study. Hum Reprod. 2021;36(4):880-890.
  • Wenker EP, Dupree JM, Langille GM, et al. The use of HCG-based combination therapy for recovery of spermatogenesis after testosterone use. J Sex Med. 2015;12(6):1334-1337. [cited as Wenker/Ramasamy per verified stats]
  • British Society for Sexual Medicine (BSSM). Guidelines on the management of sexual problems in men. 2025.
  • World Health Organization. WHO Laboratory Manual for the Examination and Processing of Human Semen. 6th ed. Geneva: WHO; 2021.

Prezerv is a self-guided planning tool. It does not provide medical advice, diagnosis, or treatment. Always consult a qualified clinician about your own situation.