Rumors on TTC forums say cough syrup can improve your chances of conception. Dr. Liz digs into the evidence to see if there’s any serious science backing this DIY fertility remedy.


By Dr. Liz Kane

You may have heard rumors on TTC forums that cough syrup can improve your chances of conception. The theory is that the active ingredient in most over-the-counter cough medications like Mucinex, guaifenesin, thins cervical mucus the same way it thins mucus in your lungs when you have a cold. We’ll dig into the evidence behind this fertility myth to see if there’s any serious science lurking behind this DIY fertility remedy.

Can cough syrups improve conception?

There are two reported studies of guaifenesin’s role in the fertility literature:  A small study by Check et al. from 1982 of 40 couples and an anecdotal case report of guaifenesin’s role in male-factor infertility through semen analysis from 2011. In Check et al., 40 couples were theorized to be suffering from female-factor infertility caused by “hostile cervical mucus.” The women were instructed to take guaifenesin, resume trying to conceive, and their pregnancy rates and changes in their cervical mucus production and quality were tracked for six months. Fifty-seven percent of women displayed “marked improvement” in mucus quality and 65% of women conceived throughout the course of study.

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It’s important to note that Check et al.’s fertility treatment study lacks an essential component needed to determine if guaifenesin in cough medicine is effective: a control group. A control group is the standard by which comparisons are made in an experiment. In this case, the control group would be a group of couples who were also diagnosed with hostile cervical mucus infertility but were not treated with guaifenesin. Since we can’t compare pregnancy rates or fertile cervical fluid changes between treated and untreated women, we don’t know if the women who took OTC medications such as Robitussin DM that contain guaifenesin had higher rates of pregnancy than women who did not. The changes in cervical mucus are promising but do not necessarily translate to an increase in pregnancy rates.

Let’s examine the Means et al., case report. In this report, a couple was unable to conceive after 18 months due to decreased sperm motility and count. After treatment with guaifenesin for two months, sperm analysis showed that both sperm count and motility significantly increased. Importantly, this is a single case study, and there are no additional published case studies or clinical trials investigating the effectiveness of guaifenesin for male-factor infertility. More research needs to be done before we can determine if guaifenesin is effective for male-factor infertility.

Keep your cough syrup for flu season

The efficacy of guaifenesin in fertility, for both men and women, is weak and not supported by controlled, clinical trials. Before doctors and scientists would recommend guaifenesin as a treatment for infertility, its efficacy would need to be evaluated and proven in large, double-blind, randomized clinical trials. As of now, the benefits are at an investigational stage. Guaifenesin may have value for the patient who wants to try an alternative therapy to increase cervical mucus changes before moving on to in-vitro fertilization, but in this context it’s important to mention that guaifenesin is a pregnancy category risk C medication, meaning it should be avoided throughout pregnancy. Although there is no conclusive evidence that guaifenesin causes fetal harm or birth defects, it’s important to only use a medication during pregnancy if the benefits outweigh the risks. If an individual were using guaifenesin to try to conceive during their fertile window, she would need to carefully monitor for pregnancy and discontinue use after a positive pregnancy test. 

How To Check The Quality Of Your Cervical Mucus

A woman to keep track of ovulation using just her fingers and her powers of observation. Cervical mucus is a fluid secreted by your cervix; it provides natural lubrication during sex, protects against infections, and helps sperm reach the egg.

The amount and type of cervical mucus that a woman’s body produces changes throughout the month. During ovulation, it will have a slippery and clear consistency, which is similar to egg whites. If you see this, get to it! This means you’re ovulating, and it’s the ideal time to have sex if you’re trying to conceive.

Interested in learning practical tips and tools to help you get pregnant? Check out Conception 101, a 64-page book written by doctors and scientists to prepare your body, mind, and life to have a baby.