Last updated on: 5/30/2008 | Author:

Can Marijuana Use Harm Male Fertility?

General Reference (not clearly pro or con)

Alison Murdoch, MD, Head of the Department of Reproductive Medicine at Newcastle Fertility Center, was quoted in an Oct. 13, 2003 BBC article:

Male fertility is quite complicated. The partners of men with low sperm counts can sometimes achieve pregnancy, and it is only when men produce very, very small amounts of sperm that they can be considered infertile.’

Oct. 13, 2003 - Alison Murdoch, MD

PRO (yes)


Charles Ksir, PhD, Professor of Psychology at the University of Wyoming, and Oakley Ray, PhD, Emeritus Professor of Psychology and Pharmacology at Vanderbilt University, wrote in their 2004 textbook Drugs, Society and Human Behavior:

Heavy marijuana smoking can decrease testosterone levels in men, although the levels are still within the normal range and the significance of those decreases in not known.

There have been reports of diminished sperm counts and abnormal sperm structure in heavy marijuana users, but again the clinical significance of these reports is not clear.

2004 - Oakley Ray, PhD Charles Ksir, PhD


Herbert Schuel, PhD, Professor Emeritus of Anatomy and Cell Biology at the University of Buffalo, and Lani Burkman, PhD, Assistant Professor of Gynecology and Obstetrics at the University of Buffalo, et al., presented their study at the 2003 annual meeting of the American Society of Reproductive Medicine, stating:

Marijuana smokers appear to have impaired fertility potential.

Smoking men have reduced semen volume and total sperm number. Seminal sperm from MJ men express abnormally high hyperactivated mobility which persists after a wash and swim-up. These sperm may burn out quickly and reduce fertility.

We note that women smoking marijuana will have elevated THC throughout their reproductive tract, thus affecting sperm in the cervix, uterus and oviduct.

2003 - Herbert Schuel, PhD Lani Burkman, PhD


Sheena Lewis, PhD, Professor and Director of the Reproductive Medicine Research Group at the Queen’s University, directed a study which was covered in a Mar. 31, 2004 article by BBC News:

The study … examined the direct effects on sperm function of THC, the active ingredient in cannabis. The group found that THC made sperm less likely to reach the egg to fertilise it.

They also discovered that the presence of cannabis impaired another crucial function of sperm – the ability to digest the egg’s protective coat with enzymes to aid its penetration.

Mar. 31, 2004 - Sheena E.M. Lewis, PhD

CON (no)


The National Organization for the Reform of Marijuana Laws (NORML) stated on its website (accessed Mar. 17, 2006):

Government experts concede that pot has no permanent effect on the male or female reproductive systems…

A couple of lab studies indicated that very heavy marijuana smoking might lower sperm counts.  However, surveys of chronic smokers have turned up no indication of infertility or other abnormalities.

Mar. 17, 2006 - National Organization for the Reform of Marijuana Laws (NORML)