Cross-sectional Survey Studies Potential for Herb-drug Interactions in Pregnant Women

Herbal and natural products (HNP) are generally considered safe, and many people take them without considering the presence of active compounds that may interact with other HNPs or prescription medications. These interactions have the potential to be severe, according to the authors. Women are the majority users of HNPs, so the possibility for herb-drug interactions (HDIs) becomes doubly concerning in the case of pregnancy, where both the mother and developing fetus can be affected. This study aimed to identify concurrent HNP use in pregnant woman taking prescription medications and determine the potential for HDIs and their clinical significance.

The study was conducted at the Royal Aberdeen Maternity Hospital, Aberdeen, Scotland, from March to August 2012. Questionnaires were administered to women either receiving a mid-trimester (18-21 weeks) scan or in the postnatal unit within the first 24 hours after delivery. Details of how participants were recruited and how the questionnaire was administered have been provided in previous publications by the authors.1,2 The questionnaire was given in English and covered the following topics: health and medications taken during pregnancy; personal use of HNPs; attitude toward HNP use during pregnancy; and demographics. Participants were given a checklist of 40 HNPs from the Medicines and Healthcare Products Regulatory Agency, along with space to list any products not mentioned on the list. Responses were self-reported and anonymous. Data were analyzed in SPSS 22.0 software using a combination of descriptive statistics and Chi-square analysis. The Natural Medicines Comprehensive Database was used to assess the potential for HDIs, which were graded as major, moderate, or minor.

A total of 889 participants (332 antenatal, 557 postnatal) completed the survey (73% response rate), of which 403 (45.3%) reported using at least one prescription medication, excluding vitamin and mineral supplements. Of those women, 181 (44.9%) were taking at least one HNP, comprising 20.4% of the total respondents. Women who were taking both prescription medications and HNPs were significantly older (P<0.05) and had a higher educational level (P<0.05) than those only taking prescription medications. A total of 91 different prescription medications were reported. In the case of women taking both prescription medications and HNPs, the majority reported taking one prescription medication (54%) and one HNP (56.9%). The most commonly reported HNPs used were chamomile (Matricaria chamomilla syn. M. recutita, Asteraceae), cranberry (Vaccinium spp., Ericaceae), ginger (Zingiber officinale, Zingiberaceae), red raspberry (Rubus idaeus, Rosaceae), and fish oil.

Among the HNPs, aloe vera (Aloe vera, Asphodelaceae), chamomile, cranberry, fish oil, ginger, Asian ginseng (Panax ginseng, Araliaceae), grapefruit (Citrus × paradisi, Rutaceae), and sage (Salvia officinalis, Lamiaceae) were identified as having potential to interact with prescription medications, according to the authors, and a list of 34 potential HDIs were identified for 23 (12.7%) of the survey participants. Of these potential interactions, one was rated major, one minor, and the rest moderate. The authors found that chamomile, ginger, grapefruit, and fish oil were responsible for 82% of all potential HDIs among participants.

The authors suggest that, based on their findings, one out of 20 pregnant women in the UK who are using both prescription medications and HNPs could be at risk of a potential HDI. They conclude that those in the medical profession that may be suggesting the use of HNPs to pregnant women should be aware of the risk of potentially severe interactions.

As the responses were self-reported and anonymous, there was no ability to follow up to determine if participants did experience any interactions. The survey did not address “OTC” medications, like acetaminophen [paracetamol], which are commonly used and also have the potential to interact with HNPs, so rates of HDIs may be higher than this study indicates. The survey was limited to one hospital, so further research in different regions could provide a more complete picture of the issue. The authors do state that given the number of births, the overall HDI are low.

The authors report no conflicts of interest.


1Pallivalapilla AR, Stewart D, Shetty A, Pande B, Singh R, McLay JS. Complementary and alternative medicine use during early pregnancy. Eur J Obstet Gynecol Reprod Biol. October 2014;181:251–255.

2Pallivalapilla AR, Stewart D, Shetty A, Pande B, Singh R, McLay JS. Use of complementary and alternative medicines during the third trimester. Obstet Gynecol. January 2015;125(1):204–211. 

McLay JS, Izzati N, Pallivalapila AR, et al. Pregnancy, prescription medicines and the potential risk of herb-drug interactions: a cross-sectional survey. BMC Complement Altern Med. December 2017;17(1):543. doi:10.1186/s12906-017-2052-1.