Why some women are taking a cold remedy to help them get pregnant – and what the evidence says

The desire to have our own biological children is hard-wired into many of us. And the desire is often felt more keenly in those struggling with infertility. So the promise of a simple solution is hard to ignore – which may be why “the Mucinex method” is trending on social media.

Many women on TikTok are attributing successful conception to their use of the widely available cough and cold medicine Mucinex – or similar over-the-counter decongestant medicines containing the active ingredient guaifenesin.

Why would a medicine designed to relieve cough and cold symptoms help women get pregnant? During unprotected sexual intercourse, sperm are deposited at the top of the vagina. To reach and fertilise the egg, the sperm must first traverse the cervix, a small canal that connects the vagina and the womb.

The cervix plays a critical role in regulating the passage of sperm through its production of cervical mucus. During a woman’s menstrual cycle, the quantity and consistency of the cervical mucus changes, becoming optimal around the time of ovulation.

If there is too much mucus, or it is too thick, it can stop the sperm from reaching the egg. So, the idea goes that by taking Mucinex, a woman would thin her cervical mucus and make it easier for the sperm to reach the egg.

The rising popularity of fertility tracking apps has increased awareness of signs of the fertile window among users, including through monitoring of cervical mucus quantity and consistency. Once familiar with their individual signs, it follows that women who are trying or, indeed, struggling to conceive might start considering how to optimise their chances of conception in any given cycle.

A simple over-the-counter product such as Mucinex could well seem like a quick and simple solution with potentially more rapid results than dieting or a change in other lifestyle factors.

Not surprisingly, questions are being asked over the validity of taking Mucinex, or other guaifenesin-containing medicines, as fertility aids.

The fact is, there is scant scientific evidence proving that Mucinex can help with fertility. The most cited scientific study is from 1982 and was published in the journal Fertility and Sterility. Here, scientists studied 40 couples whose infertility was defined as being a “cervical issue”.

The women in the study were given 200mg of guaifenesin, three times a day starting on the fifth day of their menstrual cycle. By the end of the study, 15 out of the 40 couples had become pregnant, which some may see as supporting the use of guaifenesin.

However, as there was no group that didn’t take guaifenesin (a control group), it is not possible to attribute these pregnancies solely to guaifenesin.

In a separate case study, a man took 600mg of guaifenesin, twice a day, for two months. The study reported a dramatic increase in sperm production and motility. However, as this study was conducted on a single 32-year-old man, the researchers could not confirm that guaifenesin was the cause of the change.

It should be noted that Reckitt, the makers of Mucinex, said in a statement that Mucinex should “only be used as intended in line with label directions”. And that taking Mucinex for infertility “constitutes off-label use”.

Is there any harm in taking guaifenesin to conceive?

While no associations between guaifenesin and birth defects have been identified, there is still no solid data on how guaifenesin might affect embryo development.

For those seeking to become parents, the idea of boosting your chances with a widely available medication is understandably enticing. However, there is not enough evidence to support taking guaifenesin to improve fertility.

There are a range of other simple, lifestyle changes that have been shown to help with getting pregnant. These include maintaining a healthy weight and diet, reducing alcohol intake, giving up smoking and lowering stress. For those experiencing difficulties in becoming pregnant, the best, and possibly simplest advice is to talk to your doctor.

Adam Watkins receives funding from the Biotechnology and Biological Sciences Research Council under grant BB/V006711/1.

Emma Lucas is a council member of the Society for Reproduction and Fertility.