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Drugs and Fertility

Lots of drugs affect fertility, and some of them are essential for fertility treatments, but many of them significantly reduce the chances of conception.

When we say “drugs”, we’re including hormones and all prescription and non-prescription medications, some of which can cause permanent damage to sex organs and sterility. Most of the research on drugs and fertility has been with sperm, simply because sperm are much easier to work with than eggs:

  • Sperm are much easier to access
  • There are lots of them
  • They’re constantly being made
  • Changes in sperm numbers and function can be seen in relatively short time frames
  • Sperm tests don’t reduce a man’s fertility, but taking eggs from ovaries does, so there are ethical issues

Sex and Drugs

The sex bias complicates the issue a bit, but eggs and sperm have similarities because:

  • They’re both delicate cells undergoing rapid development
  • Their DNA is particularly vulnerable
  • They’re less able to repair DNA damage than normal cells
  • However, sperm are much smaller, and there are many more of them

Some drugs interfere with how sperm develop and reduce healthy sperm numbers, while others affect sex drive and a man’s ability to maintain an erection. As men and women share the same sex hormones, it’s very likely these drugs also affect follicle development, but the lack of research on drugs and female fertility makes it unproven. However, we do have information on how some drugs affect breastfeeding mothers and their babies and therapeutic alternatives.

Non-prescription drugs and fertility

Many 18-50-year-old men take illegal drugs that affect conception rates, and an estimate of illicit drug use by men in the U.S.A is: i

Age of men Used a drug in the last year Used a drug in the past month
26-34 24.6% 14.3%
35-49 14.5% 8.7%
50+ 7.8% 5.0%

Clinical trials on illegal drugs aren’t straightforward (due to the ethics involved), but we do know:

Drug Impact on men Impact on women
Marijuana Affects the testes and sperm development, causing lower hormone levels (LH and testosterone). Sperm have lower functionality, morphology and motility. ii Disrupts the menstrual cycles and reduces the development of follicles. It lowers embryo implantation rates and development. iii
Opiates (including prescription) Reduce testosterone production, libido and erectile function.
Cocaine Impairs erectile function and may reduce sperm concentration. The children of women who take cocaine during pregnancy are more likely to develop abnormally.
Amphetamines Reduces libido.
Anabolic steroids Creates abnormal sperm, no sperm, atrophy of the testes and hypogonadism. It can take a year or more to recover fertility.

Prescription Drugs and Fertility

There’s more research on the impact of prescription drugs on men than women, with the known effects of many medications shown below: iv

Medication Effect of reproduction Length of effect
Antibiotics: Ampicillin, cephalothin, cotrimoxazole, gentamycin, neomycin, nitrofurantoin, Penicillin G, spiramycin Impairs the development of sperm Reversible
Anti-Epileptics: Phenytoin

Carbamazepine, oxcarbazepine and valproate

Valproate v

Impairs sperm motility

Many abnormal sperm in samples

Smaller testes and fewer sperm


Not known

Not known

Antihypertensives: Alpha agonists (clonidine), alpha blockers (prazocin), beta blockers,hydralazine, methyldopa, thiazide diuretics

Calcium channel blockers (nifedipine)

Erectile dysfunction

Fertilization failure

Anti-inflammatories: Mesalazine, sulfasalazine Impairs the development of sperm and sperm motility Reversible
Antimalarials: Quinine and its derivatives Impairs sperm motility Reversible
Antidepressants/ Antipsychotics: Alpha-blockers, phenothiazine (particularly SSRIs)


Increases prolactin concentrations, causes sexual dysfunction (inability to ejaculate or maintain erections) and reduces sperm motility v

Increases rates of sperm DNA Fragmentation vi

Impairs the development of sperm and sperm motility

Reversible for some men; for others, the problems persist
Corticosteroids: Reduces sperm concentration and motility Reversible
Non-steroidal anti-inflammatory drugs (NSAIDS): Cox-2 inhibitors Impairs the rupturing of the follicle and ovulation and impairs tubal function Reversible

Taking medicines is essential for many people’s health; anyone thinking of stopping their prescribed medicines should see their MD/GP as unsupervised withdrawal could have serious health consequences.

Ten “over the counter” drugs to avoid in pregnancy vi

Drug Found in Consumer Reports’ recommendation Possible alternative
Aspirinvii BayerExcedrin Migraine Not recommended Tylenol(acetaminophen)
Bismuth subsalicylate Kaopectate Pepto Bismol Use with caution before 20 weeks

Not recommended after 20 weeks


(but this also has side effects)

Bromphen-iramine Dimetapp Cold and Allergy Use with caution before 36 weeks
Not recommended after 36 weeks (9th month)
Claritin (loratadine);Zyrtec (cetirizine)
Caffeine Anacin Regular Strength, Excedrin

Extra Strength,

Excedrin Migraine

Use with caution, and to reduce the risk of miscarriage, don’t exceed 200 milligrams daily. None
Castor Oil Don’t take: an unacceptable risk Increase physical activity, drink more fluids and eat fibre-rich foods. Consider psyllium- supplements
Chlorpheniramine Chlor-Trimeton combination products:

Advil Allergy Congestion Relief

Alka-Seltzer Plus Cold Formula, Dristan Cold

Use with caution before 36 weeks

Not recommended after 36 weeks (8th month)

Claritin (loratadine);Zyrtec (cetirizine)
Ibuprofen Advil, Motrin Use with caution in weeks 14 to 26 (2nd trimester)

Not recommended before 14 weeks and after 27 weeks

(1st and 3rd trimester)

Naproxen Aleve Use with caution in weeks 14 to 26 (2nd trimester)

Not recommended before 14 weeks and after 27 weeks

(1st and 3rd trimester)

Nicotine Cigarettes and all other forms of tobacco;Nicorette gum, Nicoderm CQ patches Not recommended; however, the benefits of gum or patches to help stop smoking may exceed the risks of smoking during pregnancy. None
Phenylephrine and


Pseudo-ephedrine products: Advil Cold & Sinus, Claritin-D, Sudafed 12 Hour

Phenylephrine products:

Alka-Seltzer Plus Day, Sudafed PE Pressure + Pain, Tylenol Cold Multi-symptom, Vicks Dayquil Cold and Flu Relief

Not recommended before 14 weeks (1st trimester)

Use with caution after 14 weeks (2nd and 3rd trimester)

Drink plenty of fluids, consider using steam to relieve congestion and avoid irritants like tobacco smoke

Note: This isn’t a list of every drug to avoid during pregnancy. Always talk to your healthcare provider before taking medicines or supplements.

For scientific literature and fully referenced information on drugs and other chemicals known to affect breastfeeding mothers and their babies (with suggestions for therapeutic alternatives), please refer to the LactMed® database.


Photo by Myriam Zilles on Unsplash
i The National Survey of Drug Use and Health (NSDUH) conducted by the Department of Health and Human Services (Substance Abuse and Mental Health Services Administration [SAMHSA], 2010)
ii ‘The Insults of Illicit Drug Use on Male Fertility’ Carolyn M. Fronczak, et al. Journal of AndrologyVolume 33, Issue 4, pages 515–528, July-August 2012
iii ‘The manifold actions of endocannabinoids on female and male reproductive events.’ Bari M, et al. (PMID:21196184)
iv’ Lifestyle factors and reproductive health: taking control of your fertility’ Sharma et al. Reproductive Biology and Endocrinology 2013, 11:66

ii ’Effect of epilepsy and antiepileptic drugs on male reproductive health’ J. I.T. Isojärvi et al. Neurology January 27, 2004 vol. 62 no. 2 247-253 doi: 0.1212/01.WNL.0000098936.46730.64
vi Antidepressants may harm male fertility

‘Semen Parameters are Unrelated to BMI But Vary With SSRI Use and Prior Urological Surgery’Rachna Relwani, et al. Reproductive Sciences April 2011 vol. 18 no. 4 391-397
vi Information from Briggs GG, Freeman RK, Yaffe SJ eds. Drugs in pregnancy and lactation: a reference guide to fetal and neonatal risk. 9th ed. Wolters.
vii Low-dose aspirin (40 to 150 mg daily) may be prescribed for certain conditions associated with pregnancy such as gestational high blood pressure and pre-eclampsia.