Preview for Kara’s review. Expanded educational draft · sources checked 12 October 2026 · clinical approval pending.
Each chapter’s key idea carries an evidence label: Strong, Moderate or Limited. What the labels mean
Everyday health: useful steps and honest limits
Smoking, heavy alcohol use, some recreational drugs and anabolic steroids can be relevant to sperm health. European guidance asks clinicians to tell men about the harmful effects of obesity, inactivity, smoking and heavy drinking on sperm, and to help them change (a strong recommendation). The WHO strongly recommends brief advice to stop smoking for everyone who uses tobacco. On alcohol, the UK’s NICE says up to 14 units a week, spread over several days, is unlikely to affect semen quality, while heavy drinking harms it. Ask about work exposures if you regularly handle chemicals, radiation or high heat.
Weight matters too. NICE notes that men with a BMI of 30 or more have a higher chance of reduced fertility, and a large review linked obesity with a higher chance of a low count. Obesity in men is also linked with lower IVF live-birth rates, even when the semen analysis looks normal. In a small trial, men with obesity who lost weight and kept it off had higher sperm counts a year later. These are reasonable health goals, not a guarantee of conception, and fertility difficulties are not evidence that someone has failed to live well. Some causes cannot be changed through lifestyle.
Vaping is not a proven safe swap: young men who vaped daily had lower sperm counts in one large Danish study. Heavy cannabis use has been linked with lower sperm counts in some studies, though not with a longer time to pregnancy; if you are trying to conceive, cutting down is sensible.
Heat and everyday worries: men who mostly wore looser underwear had somewhat higher sperm counts in one clinic study, and regular saunas lowered sperm quality for a while, which recovered within months of stopping. NICE says it is uncertain whether loose underwear improves fertility. A high fever can lower sperm counts for two to three months. There is no good evidence that a phone in your pocket harms fertility; the studies are weak in both directions. COVID-19 vaccines do not harm sperm or fertility.
Supplements can make a difference to sperm quality measures in some men. In men with abnormal semen results, a 2025 review of 50 placebo-controlled trials found better sperm concentration with products combining three or more ingredients (and with zinc and folic acid, although the much larger FAZST trial found no change), and better sperm movement with selenium, carnitine or CoQ10. Another 2025 review found that antioxidants lowered sperm DNA damage a little. If a blood test shows a deficiency, such as low vitamin D, correcting it is sensible for your general health.
Trials have not yet consistently shown more babies. A Cochrane review of 90 trials found that antioxidants may increase live births, but the evidence was of very low certainty, and there was no clear increase when only the most reliable trials were counted. In one US trial (MOXI), live births within six months were 15% with an antioxidant mix and 24% with a placebo (dummy pill); in a much larger one (FAZST), folic acid and zinc gave 34% against 35%; and in a 2025 trial of 1,171 men (SUMMER), an antioxidant product did not increase pregnancies. The 2025 review of 50 trials found no evidence that any supplement increased pregnancy or live birth.
In Kara’s laboratory experience, supplements definitely make a difference: introducing them in her laboratory improved embryo quality. She compares them to premium ingredients in a recipe. They can improve the quality of the ingredients, the eggs and sperm, and can affect other factors that help the process succeed, but in her experience they don’t change sperm shape (morphology).
If you take a supplement, use the dose on the label or the one your doctor advises, choose a good-quality product, and check with your doctor or pharmacist that it does not interact with other medicines you take. Ask what a product has been shown to improve and how strong the evidence is. Supplements support treatment; they don’t replace it, so do not let them delay proper testing. The guidelines do not all agree on antioxidants, as the box below shows.
Changes in semen measures may take months to become visible. Keep appropriate follow-up rather than postponing medical evaluation while waiting for a supplement course to work. Emotional support and shared decision-making belong alongside physical care.
Stopping smoking, cutting down heavy drinking and working towards a healthy weight are worth doing for sperm quality and general health.
Read more: EAU guideline: Male infertility · WHO guideline for the prevention, diagnosis and treatment of infertility (2025) · NICE NG257: Fertility problems: assessment and treatment (2026) · Sermondade et al. (2013): body weight and sperm count, a review · Campbell et al. (2015): obesity in men and fertility treatment outcomes, a review · Andersen et al. (2022): weight loss and sperm count, a randomised trial · Holmboe et al. (2020): e-cigarettes and sperm counts in young men · Gundersen et al. (2015): cannabis and semen quality in young men · Wise et al. (2018): cannabis and time to pregnancy · Mínguez-Alarcón et al. (2018): underwear type and sperm · Garolla et al. (2013): sauna use and sperm production · Carlsen et al. (2003): fever and semen quality · Kenny et al. (2024): mobile phones and male fertility, a WHO-commissioned review · Wesselink et al. (2022): COVID-19 vaccination, infection and fertility · Huang et al. (2023): COVID-19 vaccines and semen, a review · de Ligny et al. (2022), Cochrane: antioxidants for male subfertility · Steiner et al. (2020): the MOXI antioxidant trial · Schisterman et al. (2020): the FAZST folic acid and zinc trial · Michaelsen et al. (2025): supplements for male infertility, a review of 50 trials · Szabó et al. (2025): treatments that lower sperm DNA damage, a review of 86 studies · AUA/ASRM Male Infertility guideline, amended 2024 · South African National Department of Health: National clinical guidelines for safe conception and infertility (2020) · NHS: Low sperm count
Testosterone, steroids and recovery
Testosterone and anabolic steroids switch off sperm production. When testosterone comes from outside the body, the brain senses plenty and turns down the signals (FSH and LH) that tell the testes to make sperm. Sperm counts can fall very low or to zero, even while muscles or libido respond. Guidelines in Europe, the UK and the US all say testosterone should not be used to treat male infertility.
Most men recover after stopping, but it takes time. In trials where healthy men took testosterone as a contraceptive, counts took a median of about 3.4 months to return to 20 million/mL; about two in three had recovered by 6 months, nine in ten by 12 months and all by 24 months. Recovery was slower after longer use and with longer-acting products.
Recovery after anabolic steroid use is less predictable. In a small study of former users, sperm output was estimated to take about 14 months to recover, and longer after longer use; overall recovery took about 6 to 18 months, and the testes often stayed smaller. Recovery is common but not guaranteed. European guidance suggests waiting 6 to 12 months after stopping steroids before considering fertility medicines.
If testosterone was prescribed for a medical reason, never stop it on your own. Low testosterone can cause real symptoms and health effects. Tell the prescriber that you want children, now or later, so that they can plan the safest approach with you.
Hormone treatment works best, and is clearly proven, for one group: men whose brain does not send the hormone signals to the testes (hypogonadotropic hypogonadism). Injections of those hormones (hCG, often with FSH) restart sperm production in about three out of four men, though it can take many months and some still need IVF or ICSI.
Specialists also commonly use clomifene (also spelt clomiphene), hCG or FSH for other sperm-production problems, such as a low count with no clear cause. Studies show these medicines can improve sperm counts in some men: recent reviews found that FSH and low-dose clomifene raised sperm concentration. Evidence that they lead to more pregnancies and births is still limited, and the guidelines differ, as the box below shows: the UK’s NICE is cautious, while European urologists suggest FSH can be considered for some men. Never take these medicines without a specialist, and never use testosterone itself as a fertility treatment. Ask what the treatment is aiming to improve, and how it will be monitored.
Sperm production usually returns after stopping testosterone or steroids, but it often takes many months, sometimes more than a year, and is not guaranteed.
Read more: EAU guideline: Male infertility · NICE NG257: Fertility problems: assessment and treatment (2026) · AUA/ASRM Male Infertility guideline, amended 2024 · Liu et al. (2006): sperm recovery after hormonal male contraception · Shankara-Narayana et al. (2020): recovery after anabolic steroid use · Karavolos et al. (2015): male fertility and anabolic steroids, a review · Rastrelli et al. (2014): hormone treatment for hypogonadotropic hypogonadism, a review · Konnyu et al. (2026): hormone treatment for men with normal hormones, a review · Santi et al. (2025): clomifene and FSH for men with low counts and no clear cause, a review · Al Wattar et al. (2024): clomifene, tamoxifen and other medicines, a review · Attia et al. (2013), Cochrane: FSH for unexplained male subfertility · South African National Department of Health: National clinical guidelines for safe conception and infertility (2020)
Other medicines and emotional support
Bring a complete list of prescribed medicines, over-the-counter products and supplements to your appointment. The UK’s NICE asks clinicians to check for medicines such as weight-loss injections (GLP-1 medicines), testosterone, finasteride and anabolic steroids, and for recreational drugs including cannabis.
Some everyday medicines can lower sperm quality, usually reversibly. A review of the research found good evidence of harm for only a few, including testosterone and anabolic steroids, sulfasalazine, opioid painkillers and some hormone treatments; for many others the evidence is thin. Do not stop a prescribed medicine yourself; ask your doctor whether there is a fertility-friendly option.
Some findings are reassuring. Finasteride for hair loss does not harm most men’s fertility, but in men who already have low counts, stopping it has sometimes led to big improvements in small studies, so discuss it with your doctor. Low-dose methotrexate for arthritis or psoriasis did not change semen results in a small study, so men usually do not need to stop it to try for a baby; check with your specialist. There is no good evidence that antidepressants seriously harm fertility, and untreated depression matters too.
Fertility concerns can bring uncertainty, sadness or pressure around sex. Studies show that men with infertility have more depression, anxiety and distress than fertile men, whatever the cause, and men often hide it. NICE advises offering counselling before, during and after investigations. You can seek emotional support while investigations continue; you do not need a final diagnosis first.
Erection or ejaculation problems are common when trying for a baby, partly because of the pressure. They are treatable, so mention them to your doctor.
Most medicine effects on sperm reverse after stopping, but the evidence for many medicines is thin. Review them with your doctor rather than stopping them yourself.
Read more: NICE NG257: Fertility problems: assessment and treatment (2026) · Semet et al. (2017): the impact of medicines on male fertility, a review · Amory et al. (2007): finasteride and dutasteride and semen, a randomised trial · Samplaski et al. (2013): finasteride in men with infertility · Perez-Garcia et al. (2023): methotrexate and sperm (iFAME-MTX) · dos Santos et al. (2025): antidepressants and male fertility, a review · Biggs et al. (2024): the psychological effects of infertility in men, a review · Liu et al. (2022): sexual difficulties in men with infertility, a review · EAU guideline: Male infertility
What you may be wondering
How quickly will changes show in a semen test?
Sperm development and maturation take roughly two to three months. Changes are not immediate, and improvement or pregnancy cannot be promised.
Should I stop my prescribed medicines?
Do not change treatment on your own. Bring your complete medicine and supplement list to the clinician who knows your history.
Can I ask for counselling before a diagnosis?
Yes. Emotional support can accompany investigations; you do not need a final diagnosis before asking your care team for help.
How long after stopping steroids will my sperm recover?
Often 6 to 18 months, and sometimes longer after heavy or long use. Recovery is common but not guaranteed; a semen test can check.
Common worries, explained carefully
“A supplement can guarantee better sperm or a pregnancy.”
Some supplements can improve sperm measures, but none can guarantee better sperm or a pregnancy. Ask what a product has been shown to improve, the right dose, possible interactions and the cost.
“Taking testosterone will improve sperm production.”
External testosterone can suppress the hormone signals needed for sperm production, so guidelines advise against it for men who want children now or later. Discuss fertility goals with your prescribing clinician.
“I should delay assessment until my lifestyle is perfect.”
General health changes can sit alongside appropriate investigation. They do not replace assessment of a possible underlying cause.
“Sperm come back as soon as I stop steroids.”
Recovery usually takes months, often more than a year after long or heavy use, and it is not guaranteed.
The terminology, translated
- External testosterone
- Testosterone supplied as a medicine rather than produced by the body.
- Anabolic steroids
- Drugs with testosterone-like effects that can interfere with sperm production.
- Semen parameters
- Measurements such as sperm concentration, motility and morphology.
- Antioxidant supplement
- A supplement intended to reduce oxidative damage to sperm. Some trials show better semen results, but not yet consistently more births.
- Shared decision-making
- Discussing evidence, options and personal priorities with your care team.
- Hypogonadotropic hypogonadism
- A condition in which the brain does not send the hormone signals (FSH and LH) that tell the testes to work.
- hCG
- A hormone injection that acts like LH and can restart testosterone and sperm production in some men.
- Which one or two health changes are realistic for me?
- Could any medicine or supplement affect my fertility or interact with treatment?
- Does a supplement have evidence for an outcome that matters to us?
- Where can I find emotional or relationship support?
Videos on this guide
Videos on these questions are coming to the channel:
- Sperm Health: Changes Partners Can Make
Sources & further reading
Sources 38 studies and guidelines Show the research
Prepared using Kara’s research library and checked against the linked clinical and patient-education sources. The explanations and new diagrams are original educational adaptations.
- EAU guideline: Male infertility
- WHO guideline for the prevention, diagnosis and treatment of infertility (2025)
- NICE NG257: Fertility problems: assessment and treatment (2026)
- Sermondade et al. (2013): body weight and sperm count, a review
- Campbell et al. (2015): obesity in men and fertility treatment outcomes, a review
- Andersen et al. (2022): weight loss and sperm count, a randomised trial
- Holmboe et al. (2020): e-cigarettes and sperm counts in young men
- Gundersen et al. (2015): cannabis and semen quality in young men
- Wise et al. (2018): cannabis and time to pregnancy
- Mínguez-Alarcón et al. (2018): underwear type and sperm
- Garolla et al. (2013): sauna use and sperm production
- Carlsen et al. (2003): fever and semen quality
- Kenny et al. (2024): mobile phones and male fertility, a WHO-commissioned review
- Wesselink et al. (2022): COVID-19 vaccination, infection and fertility
- Huang et al. (2023): COVID-19 vaccines and semen, a review
- de Ligny et al. (2022), Cochrane: antioxidants for male subfertility
- Steiner et al. (2020): the MOXI antioxidant trial
- Schisterman et al. (2020): the FAZST folic acid and zinc trial
- Michaelsen et al. (2025): supplements for male infertility, a review of 50 trials
- Szabó et al. (2025): treatments that lower sperm DNA damage, a review of 86 studies
- AUA/ASRM Male Infertility guideline, amended 2024
- South African National Department of Health: National clinical guidelines for safe conception and infertility (2020)
- NHS: Low sperm count
- Liu et al. (2006): sperm recovery after hormonal male contraception
- Shankara-Narayana et al. (2020): recovery after anabolic steroid use
- Karavolos et al. (2015): male fertility and anabolic steroids, a review
- Rastrelli et al. (2014): hormone treatment for hypogonadotropic hypogonadism, a review
- Konnyu et al. (2026): hormone treatment for men with normal hormones, a review
- Santi et al. (2025): clomifene and FSH for men with low counts and no clear cause, a review
- Al Wattar et al. (2024): clomifene, tamoxifen and other medicines, a review
- Attia et al. (2013), Cochrane: FSH for unexplained male subfertility
- Semet et al. (2017): the impact of medicines on male fertility, a review
- Amory et al. (2007): finasteride and dutasteride and semen, a randomised trial
- Samplaski et al. (2013): finasteride in men with infertility
- Perez-Garcia et al. (2023): methotrexate and sperm (iFAME-MTX)
- dos Santos et al. (2025): antidepressants and male fertility, a review
- Biggs et al. (2024): the psychological effects of infertility in men, a review
- Liu et al. (2022): sexual difficulties in men with infertility, a review
Fertility is a shared picture
For every couple, the health and results of both the man and the woman shape the plan. These Fertility Library topics sit alongside this guide.
