May 23 2022

Classification of the active ingredient amoxicillin

Risk level in pregnancy: This medicine is classified as Category B.

Available studies in pregnant women do not indicate a possible link between amoxicillin and the occurrence of birth defects. However, some studies suggest the possibility that the use of amoxicillin during pregnancy can be associated with cleft palate [1] [2]. In one of them, the OR for cleft palate associated with taking amoxicillin during the first quarter would be 1.0 (95% CI 0.4-2.3), while for the third month would have a significant value (OR 7.1, 95% CI: 1.4 -36) [1]. Another study points in the same direction, expressing the possibility that amoxicillin increases the risk of cleft lip associated with cleft palate, although the results do not allow conclusions on them, but indicates the need for further studies about this subject [2].

Other authors call attention to the risk of minor malformations with antibiotics riskless allegedly, such as amoxicillin. Results from an observational study shows the teratogenic potential of beta-lactams, including amoxicillin [3].

Reproduction studies in laboratory animals at doses up to ten times higher than usual in man have shown no negative influences of amoxicillin on fertility or fetus.

In conclusion, there are no adequate and well controlled studies on the use of amoxicillin during pregnancy. Because animal reproduction studies are not always predictive of the situation in humans, this drug should be used during pregnancy only if clearly needed.


1. Lin KJ, Mitchell AA, Yau WP, Louik C, Hern?ndez-D?az S. Maternal exposure to amoxicillin and the risk of oral clefts.Epidemiology. 2012 Sep;23(5):699-705. Doi: 10.1097/EDE.0b013e318258cb05.
2. Puh? EH, Szunyogh M, M?tneki J, Czeizel AE. Drug treatment during pregnancy and isolated orofacial clefts in hungary.Cleft Palate Craniofac J. 2007 Mar;44(2):194-202.
3. Eric M, Lepp?e M, Sabo A, Culig J. Beta-lactam antibiotics during pregnancy: a cross-sectional comparative study Zagreb-Novi Sad.Eur Rev Med Pharmacol Sci. 2012 Jan;16(1):103-10.

Update 18.07.2009

Meaning of category B

Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.