March 9, 2018

expert reaction to a review of studies looking at antihistamines and male fertility

Researchers publishing in Reproduction examine the association between antihistamines and the potential consequences for male fertility.

An MHRA spokesperson, said:

“MHRA is aware of the new review that suggests over-the-counter allergy drugs could have negative long-term side effects for male fertility. An impact on male fertility is not a known side effect of antihistamines, however we will keep any new evidence under review.”

“Any patient who is concerned about the use of antihistamines should contact their doctor but continue to take their medicine in the meantime.”

“Patient safety is our highest priority and as with all medicines, the safety of antihistamines is kept under constant review.”

Prof Allan Pacey, Professor of Andrology at the University of Sheffield, said:

“This is an interesting and very comprehensive review paper outlining the possible role of histamine in the reproductive system of men. However, I think the evidence is really too limited to say whether anti-histamine medication does or does not have a detrimental impact on male fertility. Most of the data discussed in the review paper comes from animal studies and there is a lack of convincing epidemiological evidence in humans to ether support or refute the idea that anti-histamines are bad for male fertility. Unfortunately we know surprisingly little about how many prescription and over the counter medicines (such as anti-histamines) may impact on male fertility, therefore, I urge doctors and scientists to include these important confounders in their studies. However, for now, I see no reason why men who need to use anti-histamines should not continue to do so.”

Prof Darren Griffin, Professor of Genetics, University of Kent, said:

“This is a clearly important and fascinating area of medicine, worthy of further study.  Indeed, the press release accurately summarises the findings.

“The paper is largely a summation of all available data on whether anti-histamines can lead to reduced male fertility.  The data presented is not new in the sense that this is a review article, but nonetheless the synopsis is timely and well written.  Any medicine that has the potential to do good also has the potential to do harm and side effects of over the counter drugs constantly warrant further investigation and the use of antihistamines is on the rise.

“The review is an encyclopaedic account of all the ways in which anti-histamines might affect normal sperm production and function.  For the most part, the studies are on model organisms (mice, rats, bulls) and the relevance to humans requires further investigation e.g. in large clinical trials. Whether the magnitudes of the possible effects on sperm count and motility would in fact appreciably affect overall fertility still remains to be seen.  The precautionary principle here might be for men to avoid taking too many anti-histamines if they are trying to procreate. Given the data presented here is mostly in animals however the jury is still out and human trials are needed

“The authors go on to mention the possible effects on penile erection, testosterone production, sexual behaviour and ejaculatory response. In any event however, persistent sneezing is not a particularly good reproductive strategy either so perhaps taking the antihistamines, when necessary, is the lesser of two evils.”

Dr Richard Quinton, member of the Society for Endocrinology and Senior Lecturer in Endocrinology at Newcastle University, said:

“This is a timely and authoritative review of human, animal and in vitro data – however, the term “antihistamine” means very different things to different people, which may lead to unnecessary anxieties in some. Most doctors, and virtually all people, will associate the term “antihistamine” with H1-blockers – these are drugs used to treat hay fever and allergies, and they are available to buy over-the-counter in many countries.

“However, the data reviewed in this publication overwhelmingly implicate a different kind of antihistamine too – H2-blockers, which used to be a common treatment for human peptic ulcer disease. Although the general data presented on histamine action and reproduction is fascinating, it’s very clear that the actions of different H2 blockers are very variable – for example, the antiandrogenic action of Cimetidine has long been recognised, but later drugs have minimal effects on male fertility.”

“The paper is looking at all aspects of histamine action, but in relation to drug effects in humans, the concerns only really arise in relation to the H2 blockers (and one in particular – Cimetidine). The findings of this paper aren’t likely to be relevant to the antihistamines we take for allergies, even though it’s a great paper overall.”

Dr Channa Jayasena, Society for Endocrinology member and Senior Clinical Lecturer, Imperial College London, said:

“The average sperm quality in the population has been reducing over the last few decades, so it is always important to consider that common (and increasingly used) medications may be partly responsible. The authors aim to summarise previous scientific studies in the field. As they rightly acknowledge, it is far too soon to raise alarm bells about taking these medications. Many agents have been linked to male infertility. The trick is working out how much overall impact they have on men’s reproductive health, which is still not known.”

* ‘Potential negative effects of anti-histamines on male reproductive function’ by Carolina Mondillo et al. published in Reproduction on Friday 9th March. 

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/tag/fertility/

Declared interests

Dr Richard Quinton: “No conflicts of interest.”

Dr Channa Jayasena: “No conflicts to declare.”