Moderate use of the popular NSAID has been found to impact hormonal balance in healthy men, potentially leading to reduced libido, infertility, depressed mood and fatigue

In the first in-depth study of its kind, researchers from Denmark have analysed how ibuprofen – used in the general population for aches, pains, fever and arthritis, and heavily used by athletes – affects the pituitary-testis axis.

To do so, they conducted a randomised controlled clinical trial involving 31 healthy men aged 18-35 years, with an ibuprofen group receiving 2 x 600mg/d while the other received placebo pills over the same period.

This was supplemented by an ex vivo organ model using adult human testis explants, as well as a standardised in vitro model using cells.

The trial results were clear: ibuprofen was found to affect the hormonal balance in adult men.

Researchers found an 18% decrease in free testosterone/luteneising hormone ratio in the ibuprofen group compared with the placebo group after 14 days, and a 23% decrease after 44 days.

The data suggested ibuprofen induced a state of compensated hypogonadism during the trial, which occurred as early as 14 days and was maintained until the end of the trial at 44 days.

Compensated hypogonadism is a condition prevalent among elderly men and associated with reproductive and physical disorders.

“Our data demonstrate that ibuprofen alters the endocrine system via selective transcriptional repression in the human testes, thereby inducing compensated hypogonadism,” say the researchers.

“The striking dual effect of ibuprofen observed [on two types of cells that produce testosterone and sperm] makes this NSAID the chemist compound, of all the chemical classes considered, with the broadest endocrine-disturbing properties identified so far in men.”

Professor Kelton Tremellen, a gynaecologist and professor of reproductive medicine at Flinders University in South Australia, says the results support the possibility that anti-inflammatory drugs like ibuprofen could result in lower testosterone levels if taken over several weeks.

“There is some theoretical concern that long-term use of this drug could potentially negatively impact on male fertility potential,” says Professor Tremellen.

“However, it is presently uncertain if taking a couple of ibuprofen tablets with a headache would cause any significant impairment of testicular function. I believe it is highly unlikely to be the case.”

He advises that men should be cautious and not take anti-inflammatory medication for long periods of time without consulting their doctor, especially if they were experiencing symptoms of low testosterone (fatigue, poor libido and mood) or infertility.