Sperm takes about 74 days to develop from start to finish. A habit you drop today won't show up in a semen sample for roughly ten weeks, so the men who see the biggest change are the ones who start three months before they try to conceive, not three weeks. Eleven factors keep surfacing in the research: heavy alcohol, smoking and vaping, recreational drugs, prolonged heat exposure, anabolic steroids, a poor diet, excess caffeine, a sedentary routine and excess weight, too little sleep, several medication classes, and abstinence periods that run too long. Each one gets its own answer below, with the evidence behind it and where to read more.
1. Alcohol
A 2014 study of 1,221 young Danish men found that drinking more than 25 units a week, roughly nine to twelve pints of beer, was linked to lower sperm concentration, a smaller total count, and more abnormally shaped sperm. Fourteen units a week, with no more than five in one sitting, is the threshold most research treats as low-risk. Read the full breakdown in Does Alcohol Affect Sperm Quality and Male Fertility?
2. Smoking and Vaping
Men who smoke show worse numbers across the board: lower count, weaker motility, more misshapen sperm. A meta-analysis using WHO's 2010 semen standards confirmed the pattern holds across studies, not just a handful of small samples. Vaping hasn't been studied to the same depth, so it doesn't get treated as a safer alternative. Most of the damage from smoking reverses within a few months of quitting, roughly the same window sperm needs to regenerate. ExSeed's 9 Evidence-Based Rules for Male Fertility covers the full case for quitting, including why vaping gets the same caution.
3. Recreational Drugs
Cannabis is the drug men ask about most, and the newest data is more reassuring than older studies suggested. A 2026 North American cohort study of 921 men found no strong link between cannabis use and sperm count or motility, though weekly users showed a small, inconsistent drop in semen volume. Cocaine and other stimulants are a different case: they're associated with reduced motility and carry cardiovascular risks that matter well beyond fertility. ExSeed's fertility rules guide separates what the evidence has settled from what it hasn't.
4. Saunas, Hot Tubs and Prolonged Heat
Sperm production runs a few degrees cooler than core body temperature, which is why the testes sit outside the body. A study on sauna exposure and spermatogenesis found measurable changes in regular sauna users, changes that reversed within a few months of stopping. One sauna session after the gym isn't the concern. Frequent or prolonged heat exposure during the months you're trying to conceive is what the evidence flags. ExSeed's fertility rules guide draws the same line: manage the heat sources with real evidence behind them, and don't lose sleep over the ones that don't, like underwear choice.
5. Anabolic Steroids and Testosterone Products
Taking external testosterone, whether prescribed TRT or an anabolic steroid, tells the body to stop producing its own. Sperm production can drop to zero. A clinical review of testosterone-induced azoospermia found recovery is common but slow, often taking six months to two years depending on how long the drug was used. Anyone on TRT and planning to conceive should raise alternatives with their doctor well before trying. ExSeed's TRT and Fertility guide covers what to ask and when to test.
6. A Poor Diet
No single food ruins a sample, but a pattern heavy on processed meat and refined carbohydrates, light on vegetables, tracks consistently with worse semen parameters across the research. The Mediterranean-style pattern, vegetables, fruit, whole grains, fish, olive oil, is the one diet with genuine evidence behind it for reproductive outcomes. It needs no supplements and no strict plan, just fewer processed meals and more of the basics. ExSeed's fertility rules guide lays out what the evidence supports, and what it doesn't (fertility supplements as a substitute for food, for one).
7. Excess Caffeine
A cohort of 2,554 young Danish men found that intake above roughly 800mg a day, about seven to eight cups of coffee, was linked to worse semen parameters than lighter drinkers showed. General health guidance puts the safe ceiling closer to 300mg a day, which leaves a wide margin. A coffee or two isn't the problem; a pot before lunch might be. The full breakdown of which drinks help and which ones to watch is in Which Drinks Are Good for Sperm?
8. A Sedentary Routine and Excess Weight
Fat tissue converts testosterone into estrogen, which throws off the hormonal balance sperm production depends on. A meta-analysis of obesity and semen quality found the link holds even in the general population, not just fertility clinic patients, with the heaviest men most likely to show low counts or, in some cases, none at all. Extreme dieting or marathon training isn't the fix, and can backfire if you under-fuel. Regular moderate exercise and a weight in a healthy range are what the evidence supports. ExSeed's fertility rules guide covers both sides of that balance.
9. Too Little Sleep
Testosterone production happens mostly during sleep, and cutting it short shows up fast. In a JAMA study, healthy young men restricted to five hours of sleep a night for one week saw daytime testosterone fall by 10 to 15%, a drop similar to what a decade of natural aging produces, compressed into seven days. Sperm production responds more slowly to sleep changes than testosterone does, but the hormonal disruption matters if short sleep runs for months rather than one bad week.
10. Certain Medications
Several drug classes interfere with sperm production or ejaculation, and none should be stopped without a doctor's input first. Alpha-blockers can reduce ejaculate volume. SSRIs are linked to lower sperm counts and weaker motility. Chemotherapy can suppress production severely, sometimes permanently. Opioids disrupt testosterone. Even some ADHD medications and erectile dysfunction drugs interact with fertility in ways worth knowing before trying to conceive. ExSeed's guide to ADHD medication, Viagra and male fertility covers two of the most common questions in detail.
11. Abstinence Periods That Run Too Long
More isn't always better. A longer gap between ejaculations does raise total sperm count, but research comparing one day of abstinence to four found the shorter window produced better motility and less DNA damage, even with a lower count. Two to four days is the range most fertility guidelines recommend before trying to conceive or giving a sample for testing. A week or more without ejaculating doesn't improve your odds and may work against them. ExSeed's guide to masturbation and sperm health covers why frequent ejaculation isn't the problem some men assume.
The Short Version
Three months matters more than three weeks. Sperm takes about 74 days to regenerate, so changes made today won't fully show up in a semen sample until roughly ten weeks from now. Cut back on the items above as early as possible, and check where you actually stand with a home sperm test before you start.
Frequently Asked Questions
What should men avoid when trying to conceive?
The eleven factors with the most consistent evidence behind them are heavy alcohol, smoking and vaping, recreational drugs, prolonged heat exposure, anabolic steroids or TRT, a poor diet, excess caffeine, a sedentary routine and excess weight, too little sleep, several medication classes, and abstinence periods longer than about four days. None of them alone determines fertility, but cutting back on several at once, starting at least three months before trying to conceive, gives sperm quality the best chance to improve.
How much alcohol is safe when trying to conceive?
Up to 14 units a week, with no more than 5 in a single sitting, is the threshold most research supports. Men drinking more than 25 units a week showed measurably lower sperm concentration and count in a study of over 1,200 Danish men.
Does vaping affect sperm the same way smoking does?
It might, but the research isn't there yet. Smoking's effects on sperm count and motility are well documented across large studies. Vaping hasn't been studied to the same degree, so it shouldn't be treated as a safe alternative while trying to conceive.
How long after quitting smoking does sperm quality recover?
Most of the improvement shows up within a few months, in line with the roughly 74 days sperm takes to fully regenerate. Quitting at least three months before trying to conceive gives the body that full cycle to recover.
Is caffeine safe when trying to conceive?
A cup or two a day isn't a concern. Research on more than 2,500 men found that intake above roughly 800mg a day, about seven to eight cups of coffee, was linked to worse semen parameters. Staying under 300mg a day keeps a comfortable margin.
Can being overweight cause infertility in men?
It can contribute to it. Excess body fat converts testosterone into estrogen, which disrupts the hormonal signals sperm production depends on. Research links obesity to lower sperm counts and, in more severe cases, to azoospermia (no sperm in the ejaculate).
How long should you abstain before trying to conceive?
Two to four days is the range most fertility research points to. Shorter gaps tend to produce better motility and less DNA damage than longer ones, even though a longer wait produces a higher total count.
Which medications can lower sperm count?
Alpha-blockers, SSRIs, chemotherapy drugs, opioids, and testosterone replacement therapy are among the classes linked to reduced sperm count or motility. Never stop a prescribed medication without talking to a doctor first. Some effects are temporary and manageable with the right guidance.
