Why testosterone lowers sperm
Your brain controls your testes with two hormones, LH and FSH. LH tells the testes to make testosterone, and that testosterone, at very high concentration inside the testes, is what drives sperm production. When you take testosterone, your brain senses plenty in the blood and turns LH and FSH down. The testes quiet down, the testosterone inside them falls, and sperm production drops with it, even though the level in your blood looks normal.
That is why a man can feel better, have perfect-looking bloodwork, and still have little or no sperm. Our TRT guide covers the mechanism in more detail, and the side effects guide puts fertility in context with the other risks.
What the guidelines say
- American Urological Association (2018, validity reconfirmed 2024): testosterone should not be prescribed to men currently trying to conceive (a strong recommendation); the long-term effect on sperm production should be discussed with men who want future fertility (strong); and men with low testosterone who want fertility should have a reproductive health evaluation before treatment.
- Endocrine Society (2018): advises against starting testosterone in men who plan near-term fertility.
- Fertility-sparing treatments: the AUA says clinicians may use aromatase inhibitors, hCG, or selective estrogen receptor modulators (SERMs, a class that includes clomiphene), alone or combined, but rates this as a conditional recommendation based on lower-grade evidence. The Endocrine Society does not formally endorse hCG alongside TRT.
In plain terms: the standard of care is to avoid testosterone if you want children soon, and to use fertility-sparing alternatives if you still need treatment. The alternatives work, but the evidence behind them is thinner than for testosterone itself.
Will sperm come back?
Usually, but the picture is less clean than most online sources suggest. Two kinds of evidence exist, and neither is perfect.
Evidence from healthy men in contraceptive trials
A pooled analysis of 30 studies of 1,549 healthy men given testosterone-based hormonal contraception found that sperm concentration returned to 20 million per mL at a median of 3.4 months after stopping. About 67% had recovered within 6 months, 90% within 12 months, 96% within 16 months, and all within 24 months. Recovery was faster in older men, with shorter treatment, and with shorter-acting testosterone. The caveat is important: these were healthy men on contraceptive regimens, not men with low testosterone on years of therapy.
Evidence from men who developed infertility after TRT
A study of 66 men who came to a male-infertility clinic after using testosterone found that after stopping it and taking hCG plus a SERM, 70% reached a total motile sperm count above 5 million within 12 months. Older age and longer testosterone use both predicted slower recovery. This group was by definition men with a problem, so it overstates how often TRT causes lasting harm, but it shows that recovery can take a year or more and isn't guaranteed.
The practical takeaway: expect months, not weeks, and plan accordingly if you are thinking about stopping TRT to start a family.
Options if fertility matters
1. Enclomiphene
Enclomiphene is not testosterone. It blocks estrogen's braking signal in the brain, so the brain increases LH and FSH and your testes make more of their own testosterone and keep making sperm. It only works if your testes are healthy and the problem is a weak signal (secondary low T). It does nothing for primary testicular failure. For how it compares with TRT on testosterone levels, symptoms, and safety, see enclomiphene vs TRT.
The evidence is encouraging but limited. A phase II trial found enclomiphene raised testosterone to levels similar to topical testosterone gel while preserving sperm counts. A larger pair of phase III trials followed overweight men aged 18 to 60 with secondary low T for 16 weeks: enclomiphene raised testosterone and kept sperm concentration in the normal range, while testosterone gel markedly reduced sperm production.
The big catch is regulatory. Enclomiphene is not FDA-approved for any use. It is dispensed by compounding pharmacies, and in 2022 an FDA advisory committee voted 8 to 4 against adding it to the list of bulk substances allowed for compounding. Compounded products are not FDA-approved products, and the trials were short. Ask any provider where it comes from. See our providers that offer oral options.
2. Clomiphene
Clomiphene is the older, off-label cousin of enclomiphene, used for the same purpose and approved by FDA for female infertility. A retrospective review of 400 men treated for a mean of about two years found 88% of those treated more than three years reached normal testosterone, with side effects in 8% (mood changes, blurred vision, breast tenderness most often). The abstract did not report semen results, so its fertility benefit rests on other studies.
3. hCG alongside testosterone
hCG mimics LH, so it keeps the testes working while you take testosterone. In a small retrospective study of 26 men on TRT who also took 500 IU of hCG every other day, none became azoospermic and 9 contributed to a partner's pregnancy during follow-up. That is encouraging, but it was small, uncontrolled, and short (average follow-up about 6 months). It is common in practice but not a formally endorsed guideline strategy, and it adds injections and cost. It also isn't a reason to start TRT while actively trying to conceive; AUA still says not to.
4. Banking sperm first
Freezing sperm before starting treatment is a straightforward insurance policy if you may want children later and have to go on TRT. A reproductive urologist or fertility clinic can arrange it, along with a baseline semen analysis.
The options side by side
| Option | How it protects sperm | Evidence | Main catches |
|---|---|---|---|
| Enclomiphene | Raises LH/FSH so testes make their own testosterone and sperm | Phase II and III trials, 16 weeks | Not FDA-approved; compounded; secondary low T only |
| Clomiphene | Same mechanism | Large retrospective safety review | Off-label for men; side effects in some; semen data limited in the review we cite |
| TRT plus hCG | hCG replaces the missing LH signal | Small retrospective study | Not guideline-endorsed; extra injections; AUA still says not to use TRT while trying to conceive |
| Sperm banking | Preserves sperm before treatment | Standard fertility practice | Cost and logistics; doesn't protect later production |
| Stopping TRT | Lets the signal return | Contraceptive and infertility-clinic data above | Recovery takes months and isn't guaranteed |
TRT is not birth control
Sperm counts drop on testosterone, but suppression varies from man to man and isn't reliable enough to prevent pregnancy. If avoiding pregnancy matters, use a proper contraceptive method.
Before you start
- Say it first. Tell your clinician if you want children now or in the next few years.
- Get a baseline semen analysis and, if kids are a possibility, consider banking sperm.
- Know which type of low T you have. LH and FSH results decide whether enclomiphene or clomiphene is even an option. See low T symptoms and diagnosis.
- Ask the provider what they offer. Do they prescribe enclomiphene, clomiphene, or hCG? Where does it come from? Will they order semen analyses? Our Atlas Score's access criterion considers whether fertility options are listed. Compare in the directory.
- See a specialist if needed. A reproductive urologist handles the low-T-plus-fertility problem all day. For the wider picture, including semen analysis and other causes, see our male fertility guide.
Sources
- Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and management of testosterone deficiency: AUA guideline. J Urol. 2018;200(2):423-432 (validity reconfirmed 2024). American Urological Association
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PubMed
- Liu PY, Swerdloff RS, Christenson PD, et al. Rate, extent, and modifiers of spermatogenic recovery after hormonal male contraception: an integrated analysis. Lancet. 2006;367(9520):1412-1420. PubMed
- Kohn TP, Louis MR, Pickett SM, et al. Age and duration of testosterone therapy predict time to return of sperm count after human chorionic gonadotropin therapy. Fertil Steril. 2017;107(2):351-357. PubMed
- Wiehle RD, Fontenot GK, Wike J, et al. Enclomiphene citrate stimulates testosterone production while preventing oligospermia: a randomized phase II clinical trial comparing topical testosterone. Fertil Steril. 2014;102(3):720-727. PubMed
- Kim ED, McCullough A, Kaminetsky J. Oral enclomiphene citrate raises testosterone and preserves sperm counts in obese hypogonadal men, unlike topical testosterone. BJU Int. 2016;117(4):677-685. PubMed
- Krzastek SC, Sharma D, Abdullah N, et al. Long-term safety and efficacy of clomiphene citrate for the treatment of hypogonadism. J Urol. 2019;202(5):1029-1035. PubMed
- 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. PubMed
- U.S. Food and Drug Administration. Pharmacy Compounding Advisory Committee meeting, June 8, 2022 (enclomiphene citrate).