Introduction to sperm, drugs, tobacco and alcohol

Tobacco and alcoholA healthy male produces millions of sperm each day, althoughonly a few of these sperm will ever go on to fertilise an egg and create an embryo. Despite the vast quantity of sperm produced by a healthy man, the number of sperm which actually fulfil their fertilising potential is therefore extremely small. Even when a man is producing sperm at a healthy capacity and his partner is fertile, it is not uncommon for couples to take up to a year to conceive.

Some men produce sperm which is suboptimal, either in quantity or quality. These men will typically take longer to conceive and are more likely to require the assistance of artificial reproduction techniques to do so. Some men may experience suboptimal sperm production because of a genetic or birth trait (e.g. deletions on the Y chromosome or history of cryptorchidism). In many cases, sperm production declines over time as a result of exposure to a range of risk factors.

Drugs, tobacco and alcohol allhave a range of short and long term health effects, including effects detrimental tothe production of sperm. These effects include reduced concentrations of sperm in the semen and reduced concentrations of sperm which have a normal shape and are able to move or swim. Men who are trying unsuccessfully to conceive, and those who wish to protect the health of their sperm for the future, should therefore avoid a range of drugs, including alcohol and tobacco.

Male reproductive system For more information about sperm, see the Male Reproductive System.

Smoking tobacco

A number of studies have reported an association between tobacco smoking and male infertility and/or suboptimal sperm production.A review of observational studies on smoking and semen parameters found that 20 of the 25 studies reported an increased risk of lower sperm concentration in smokers compared to non-smokers. On average, sperm concentration was 13% lower in smokers compared tonon-smokers. Smoking men also had a lower average proportion of sperm that were motile (moving or swimming) and morphologically normal (sperm with a correct body shape), compared to non-smoking men.
Smoking For more information on smoking and its health effects, and some useful tools, videos and animations, see Smoking.

Performance enhancing drugs

A number of performance enhancing and recreational drugs affect male fertility. Performance enhancing drugs (e.g.anabolic steroids) are associated with subfertility in men. They cause men to become subfertile by changing the concentrations of various hormones that influence the sperm production process.

The hormone-altering effect caused by consuming performance enhancing drugs is reversible.Normal hormone levels should return 612 months aftera man has stopped taking these drugs.


Recreational drugs (including alcohol)

Recreational drugs(also called lifestyle drugs) include marijuana, alcohol, heroin and cocaine. These drugs can impair sperm production and/or quality.

Long term overconsumption of alcohol is associated with decreased semen parameters (decreases in one or more of the measures of semen quality) as determined by semen analysis testing, and detrimental changes in hormonal levels.

Alcohol For more information on drinking alcohol, including drinking disorders and alcohol’s effect on the body, as well as some useful tools, see Alcohol.

Drugs used for medical treatment

Drugs used in medical treatment can also affect male fertility. Those used in chemotherapy are particularly well known for their irreversible affect on sperm production. It is not uncommon for men who have undergone chemotherapy to be left sterile by the treatment.

Medications that change the body’s hormonal environment (e.g. testosterone injection,anti-androgenic drugs) can also impair sperm production. This is because hormones regulate the sperm production process, and changes to hormone levels therefore affect sperm production.

Sex after cancer For more information, see sexual difficulties associated with cancer in men.

Keeping sperm healthy: Drug-related measures to protect sperm

Many of the drugs that affect sperm health are lifestyle drugs, that is, drugs taken for recreation rather than medical purposes. As such, there are a range of lifestyle modifications individuals can make in the interests of maintaining sperm health, including:

  • Stopping smoking;
  • Minimising alcohol consumption;
  • Avoiding anabolic steroids and other performance enhancing drugs; and
  • Avoiding marijuana, cocaine and other recreational drugs.

Some of the drugs that affect male fertility are used for medical purposes, and in some cases for life-saving medical treatment, so avoidance may not always be possible. In these cases, individuals should investigate the possibility of cryopreserving spermbefore undertakingfertility-threatening treatments such as chemotherapy. Cryopreserved sperm can then be used in assisted reproductive technologies such as in vitro fertilisation (IVF).

More information

Semen analysis Formore information on sperm health and male fertility, see Sperm Health


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