This sheet is about exposure to guaifenesin in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is guaifenesin?

Guaifenesin is an expectorant. Expectorants are used to thin and loosen mucus in the throat and lungs. This makes it easier to cough up and remove the mucus from the body. Guaifenesin can be found in many different products. A common brand name is Mucinex®. Guaifenesin is also used in combination with other medication in over-the-counter cough and cold preparations.

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.

I take guaifenesin. Can it make it harder for me to get pregnant?

Based on the studies reviewed, guaifenesin is not expected to make it harder to get pregnant.

Does taking guaifenesin increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if guaifenesin increases the chance of miscarriage.

Does taking guaifenesin increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Based on the studies reviewed, guaifenesin is not expected to greatly increase the chance of birth defects above the background risk. There are a few studies that suggest an increased chance for some birth defects. However, most available information suggests that if guaifenesin does increase the chance for birth defects, that increase is expected to be low.

Does taking guaifenesin in pregnancy increase the chance of other pregnancy-related problems?

Studies have not been done to see if guaifenesin can increase the chance for pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth.

Does taking guaifenesin in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if guaifenesin can cause behavior or learning issues for the child.

Breastfeeding while taking guaifenesin:

The use of guaifenesin while breastfeeding has not been studied. It is not known if guaifenesin passes into breastmilk or what effect (if any) it could have on a child that is nursing. According to the product label, when used as directed, guaifenesin is not expected to cause side effects in a child that is nursing. If a product containing guaifenesin is used during pregnancy or breastfeeding, it should be alcohol-free. Be sure to talk to your healthcare provider about all your breastfeeding questions.

If a male takes guaifenesin, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?

There is a case report in which improvement in sperm count and movement (motility) was noted after treatment with guaifenesin. However, it is not known if guaifenesin can increase the chance for conception. Studies have not been done to see if guaifenesin could increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

Selected References:

• Aselton P, et al. 1985. First-trimester drug use and congenital disorders. Obstet Gynecol 65:451-5. [PubMed: 3982720]
• Check J, et al. 1982. Improvement of cervical mucus factor with guaifenesin. Fertility and Sterility, 37(5): 707-708. [PubMed: 6896190]
• Briggs GG, et al. 2017. Drugs in pregnancy and lactation: a reference guide to fetal and neonatal risk. 11th ed. Cao Y, et al. 2021. Maternal use of cough medications during early pregnancy and selected birth defects: a US multisite, case-control study. BMJ Open, 11: e053604.
• Check JH, et al. 1982. Improvement of cervical factor with guaifenesin. Fertil Steril 37:707-8. [PubMed: 6896190]
• Dicpinigattis, et al.. 2003. Effects of guaifenesin on cough reflex and sensitivity. Chest Journal, 126(6): 2178-2181. [PubMed: 14665498]
• Dude C, et al. 2021. Assessment of the Safety of Common Medications Used During Pregnancy. JAMA, 326(23):2421-2422. [PubMed: 34932091]
• Heinonen OP, et al. 1977. Birth defects and drugs in pregnancy. Littleton, MA: Publishing Sciences Group.
• Means G, et al. 2010. Guaifenesin and increased sperm motility: a preliminary case report. Int J Gen Med, 4: 13-14. [PMC free article: PMC3056325] [PubMed: 21403786]
• PDR.Net. 2023. Guaifenesin-Drug Summary. PDR.Net Accessed January 31, 2023. https://www​.pdr.net/drug-summary​/Mucinex-guaifenesin-1275.
• Servey J, et al. 2014, Over-the-Counter Medications in Pregnancy. Am Fam Physician, 90(8):548-55. [PubMed: 25369643]
• Shaw G, et al. 1998. Maternal illness, including fever, and medication use as risk factors for neural tube defects. Teratology, 57: 1-7. [PubMed: 9516745]
• Silva R, Lee J, et al. 2007. Is guaifenesin safe during pregnancy? J. Family Practice 56 (8): 669-670. [PubMed: 17669294]