Information last updated: May 2023
The baseline risk of major birth defects in Canada is 3-5%. This means that 3-5 out of 100 babies born in the general population in Canada will be born with a major birth defect. There are also baseline risks for miscarriages (15-25 out of 100 pregnancies), prematurity and other outcomes. The information provided will summarize if taking this drug is likely to change these risks.
Summary: Approximately 1000 pregnancies with exposure to guaifenesin were included in published studies. Based on these studies it is not expected that taking guaifenesin during pregnancy will cause more babies to be born with birth defects than in the general population.
This information about guaifenesin is of a general nature and about medical use and does not replace the medical care and advice of your healthcare provider. For questions on dose, timing, side effects, interactions, etc. please consult your healthcare provider. Additionally, please read the patient insert provided with your medication.
Although participants in the studies referenced below may have used guaifenesin in various combinations, the studies usually do not provide detailed information on drug combinations. This makes it challenging to comment on the safety of using this medication in combination with others during pregnancy or lactation.
Guaifenesin helps to make mucus/phlegm thinner, so it is easier to cough it out. This type of medication is called an expectorant.
It is found in many cough and cold preparations.
If the product you are using contains other active ingredients, please check our Exposures A to Z for available information on the ingredient(s).
For more information on treating cough and cold while pregnant or providing your breastmilk to an infant, please see Treating the Common Cold in Pregnancy and Lactation.
Pronunciation
(gwye FEN e sin)
Please check back. We are in the process of reviewing if there is available information on the pre-pregnancy effects of guaifenesin.
Seven studies reported on over 1000 exposures of guaifenesin in pregnancy. Six studies reported no increased risk. One study suggested there may be a very small risk for some birth defects. However, due to the study design, these findings could have happened by chance and do not represent a real risk. Even if the findings were real, the chance of these birth defects occurring remains low (approximately 1 in 1000 or lower).
No published studies were found addressing miscarriages, prematurity, or other pregnancy outcomes with use of guaifenesin in pregnancy.
Please check back. We are in the process of reviewing if there is available information on the effects of paternal exposure to guaifenesin.
We did not find published studies on the effects of guaifenesin use in pregnancy on the newborn. We will update this section if studies become available.
If you are taking medications and you notice any new health concerns or symptoms in your nursing infant, please contact their health care provider. In case of emergency, please go to the emergency room or call 911.
People who are taking a medication or substance while providing their breastmilk to an infant need to know how much of the medication or substance is passing into their milk. One of the commonly used measurements to estimate this is the Relative Infant Dose (RID). The RID is estimated by comparing the dose of drug taken in by the infant through breastmilk to the dose that the nursing parent takes. Most medications with an RID of less than 10% are usually compatible with nursing a healthy infant. The RID does not need to be calculated for each person because most of the time it is expected to be similar to what has been found in research studies. We will provide the RID in the information below, when available.
Based on guaifenesin properties, it is assumed that some of it may pass into breastmilk. It is unknown how much guaifenesin can pass into breastmilk, as there are no studies on guaifenesin use during nursing.
A study looked at the behaviour of 5-6 year old children whose mothers had a cold or flu at months 2 to 5 of pregnancy. Parents and teachers were asked to complete a questionnaire about the children’s behaviour. Each completed questionnaire received a score. Over 95% (95 out of 100) of the children scored in the normal range. The authors did not state if any of the children exposed to guaifenesin scored in the problematic range. The average score of the 18 children whose mothers had taken guaifenesin for their cold/flu was slightly higher in the questionnaire completed by parents but not in the questionnaire completed by teachers. The fact that the authors compared average scores between the groups rather than comparing how many children scored in the problematic range in each group, as well as the normal scores in the teacher questionnaires, and the small number of exposed children included suggests that a real increase in the risk for behavioural problems is unlikely
Costs of some medications are covered for eligible people under provincial or national Indigenous drug benefit plans. Please visit the Ontario Drug Benefit (ODB) program Check medication coverage or the Non-Insured Health Benefits (NIHB) program Drug Benefit List to check if guaifenesin is covered for you.
One of the largest studies from the United States including 25,000 infants (556 exposed to guaifenesin during pregnancy) provided information on maternal race/ethnicity of the study population: non-Hispanic white (57.4-62.5%), non-Hispanic black (8.4-11%), Hispanic (25.1-34.1%) and other (6.1-6.7%). However, they did not look if there were differences in the outcomes between these groups.
Medications, if not taken as prescribed, if taken beyond the prescribed amount, or if taken in combination with certain other drugs, may cause harm to you and/or your pregnancy or your nursing child.
If you are using drugs or medications for non-medical reasons or beyond what was recommended by your healthcare practitioner and you are pregnant, providing your breastmilk to an infant, or parenting please click here Harm Reduction for additional information. In case of emergency, please go to the emergency room or call 911.
Pregnancy:
Approximately 1000 pregnancies with exposure to guaifenesin were included in published studies. Based on these studies, the use of guaifenesin during pregnancy is not expected to increase the risk for major birth defects above the baseline risk.
One case-control study including 556 exposed pregnancies examined the risk for 19 major congenital malformations. They reported associations between exposure to guaifenesin with spina bifida (12 cases, adjusted Odds Ratio (aOR) 2.2, 95% CI 1.1-4.3), small intestinal atresia/ stenosis (12 cases, aOR 2.1, 95% CI 1.1-4.0). In addition, they reported that exposure to both guaifenesin and dextromethorphan during the first trimester was associated with increased risk of gastroschisis (13 cases, aOR 3.2, 95% CI 1.5- 6.9). They also reported an association with overall Neural Tube Defects (17 cases, aOR 1.8, 95% CI 1.0-3.3) and cleft lip with/without cleft palate (50 cases, aOR 1.4, 95% CI 1.0-1.9), however these did not reach statistical significance as the lower limit of the confidence interval (CI) is one. Although these results show an association between guaifenesin and some congenital malformations, it is important to keep in mind when interpreting them that these results were not adjusted for the multiple associations analyzed, and thus may represent chance findings. As well, there was no comparison to children born with other malformations to address the risk for recall bias which is inherent to such a study. Even assuming the reported associations are true, the chance of these birth defects occurring remains low (≤ 1 in 1000).
An association with behavioural problems (as measured by parent report-Child Behavior Checklist (CBCL)) was reported in a study which included 18 children, 5-6 years old, exposed to guaifenesin during months 2 to 5 of pregnancy for a maternal upper respiratory tract infection (URI). These results need to be interpreted with caution as only the parent questionnaire scores and not the teacher questionnaire scores suggested an association. As well, the authors compared average scores between the groups but did not provide information if the scores were in the clinically significant range for problematic behaviour. The authors did mention that over 95% of the entire study group scored in the normal range on the CBCL. Additional limitations of the study are that there was a very small number of exposed children, and no information on exposure after 5 months of pregnancy.
No published studies were found addressing miscarriages, prematurity, or other pregnancy outcomes with use of guaifenesin in pregnancy.
Lactation:
One of the factors that helps to determine if a medication is compatible with nursing is the Relative Infant Dose (RID). The RID provides an estimate of infant’s exposure to a medication through breastmilk. It is the ratio between the infant’s and the nursing individual’s weight-adjusted doses. The infant weight adjusted dose is estimated based on the concentration of medication in breastmilk, and an assumption of infant daily milk consumption of 150 ml/kg/day. In general, for infants with normal growth and development, most medications with an RID of less than 10% are considered compatible with nursing. The RID does not account for infant’s drug metabolism, clearance, or infant blood levels. Although some variability may exist in the RID, in most cases the estimated RID is adequate for clinical purposes and does not need to be calculated for each individual. We will provide the RID in the information below, when available.
There are no published studies on the transfer of guaifenesin into breastmilk.
The molecular weight of guaifenesin is 198 g/mol, and therefore the molecule is small enough to pass into breastmilk.
Harm Reduction:
If your patient may be using drugs or medications not as indicated during pregnancy, while providing breastmilk to an infant, or parenting please click here Harm Reduction for additional information. In case of emergency, please advise them to go to the emergency room or call 911.
For additional resources see
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Cao Y, Rhoads A, Burns T, Carnahan RM, Conway KM, Werler MM, et al. Maternal use of cough medications during early pregnancy and selected birth defects: A US multisite, case-control study. BMJ Open. 2021;11(12):e053604.[PMID: 636846595].
Heinonen OP, Slone D, S. S. Birth defects and drugs in pregnancy. Littleton, Massachusetts, USA: Publishing Sciences Group Inc; 1977.
Lind JN, Tinker SC, Broussard CS, Reefhuis J, Carmichael SL, Honein MA, et al. Maternal medication and herbal use and risk for hypospadias: data from the National Birth Defects Prevention Study, 1997-2007. Pharmacoepidemiol Drug Saf. 2013;22(7):783-93.[PMID: 23620412].
Parker SE, Lijewski VA, Janulewicz PA, Collett BR, Speltz ML, Werler MM. Upper respiratory infection during pregnancy and neurodevelopmental outcomes among offspring. Neurotoxicology and Teratology. 2016;57:54-9.[PMID: 612497056].
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Public Health Agency of Canada. Congenital Anomalies in Canada 2013: A Perinatal Health Surveillance Report. [Internet]. Ottawa: Public Health Agency of Canada; 2013 Sept [cited 2023 September 8]. Available from: https://publications.gc.ca/collections/collection_2014/aspc-phac/HP35-40-2013-eng.pdf
Public Health Agency of Canada. Family-centred maternity and newborn care: National guidelines Chapter 7: Loss and grief. [Internet]. Ottawa: Public Health Agency of Canada; 2022 Aug 10 [cited 2023 September 9]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/maternity-newborn-care-guidelines-chapter-7.html
Shaw GM, Todoroff K, Velie EM, Lammer EJ. Maternal illness, including fever and medication use as risk factors for neural tube defects. Teratology. 1998;57(1):1-7.[PMID: 9516745].
Werler MM, Sheehan JE, Mitchell AA. Maternal medication use and risks of gastroschisis and small intestinal atresia. American Journal of Epidemiology. 2002;155(1):26-31.[PMID: 34042429].
Werler MM, Yazdy MM, Kasser JR, Mahan ST, Meyer RE, Anderka M, et al. Medication use in pregnancy in relation to the risk of isolated clubfoot in offspring. American Journal of Epidemiology. 2014;180(1):86-93.[PMID: 373487248].
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