In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to mesalamine may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is mesalamine?

Mesalamine is an anti-inflammatory (reduces inflammation or swelling) prescription medication used to treat inflammatory bowel disease. Other names for mesalamine are mesalazine and 5-aminosalicylic acid (5-ASA). Mesalamine can be taken orally (Apriso®, Asacol®, Delzicol®, Lialda®, Pentasa®) or rectally (Canasa®, Rowasa®, Pentasa®).

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

Studies on women have not yet been done to see if mesalamine could make it harder for a woman to get pregnant.

Should I stop taking mesalamine before I try to get pregnant?

You should not stop taking your medication without first speaking with your health care provider. It is important to consider the benefits of controlling your inflammatory bowel disease during pregnancy. Untreated inflammatory bowel disease increases the risk for complications for both the mother and the baby. For more information about inflammatory bowel disease in pregnancy, please see the MotherToBaby fact sheet Inflammatory Bowel Disease at

Individuals break down medications at different rates and this medication is available in different forms (extended or delayed). Some forms take longer to clear from the body than others. In general, it can take up to 6 days for almost all of the medication to clear your system.

Does taking mesalamine increase the chance for miscarriage?

One study among 146 women who used mesalamine in the first trimester did not find a higher chance of miscarriage. Another study with 100 women who used 5-ASA medications also did not notice a greater chance for miscarriage.

Can taking mesalamine during my pregnancy cause birth defects?

Exposure to mesalamine is unlikely to increase the chance for birth defects. There have been several studies among women exposed to mesalamine or a similar medication in the first trimester (one study had over 550 women enrolled) that have found no increased chance for birth defects. In contrast, another study that reviewed medical records on a little over 2,000 infants whose mothers said they used mesalamine at some time during the first trimester of pregnancy found a slightly higher chance of heart defects. Because many of these women had also used other medications, it is difficult to know if mesalamine, a combination of medications, or the underlying disease contributed to the slightly higher rate for heart defects.

Can I take mesalamine while breastfeeding?

Probably. Mesalamine has been found in breastmilk in small amounts. Reports of diarrhea occurring in breastfed infants suggest that some infants may be sensitive to mesalamine in the breastmilk. There is one report that suggests that this may even happen with rectal exposure in the mother. In contrast, there have also been reports of breastfed infants who did not have adverse effects. When taking mesalamine while breastfeeding, the nursing infant should be watched closely for changes in bowel activity. Be sure to talk to your healthcare provider about your breastfeeding questions.

What if the father of the baby takes mesalamine?

There have been some reports of men who had lower sperm count while taking mesalamine but the sperm count returned to normal after stopping the medication. There are no studies looking at possible risks to a pregnancy when the father takes mesalamine. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet on Paternal Exposures and Pregnancy at

MotherToBaby is currently conducting a study looking at inflammatory bowel disease and the medications used to treat this condition in pregnancy. If you are interested in learning more, please call 1-877-311-8972 or visit

Selected References

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  • Chermesh I & Eliakim R. 2004. Mesalazine-induced reversible infertility in a young male. Dig Liver Dis 36:551-2.
  • Colombel J-F et al. 1994. Renal insufficiency in infant: side-effect of prenatal exposure to mesalazine? Lancet 344(8922):620-621.
  • Diav-Citrin O, et al. 1998. The safety of mesalamine in human pregnancy: a prospective controlled cohort study. Gastroenterology; 114:23-28.
  • Ek S, Rosenborg S. 2017. Mesalazine as a cause of fetal anemia and hydrops fetalis: A case report. Medicine (Baltimore) 96(50): e9277.
  • Källén B. 2014. Maternal use of 5-aminosalicylates in early pregnancy and congenital malformation risk in the offspring. Scand J Gastroenterol; 49(4):442-8.
  • Mahadevan U, Matro R. Care of the pregnant patient with inflammatory bowel disease. Obstet Gynecol. 2015;126:401-12.
  • Marteau P & Devaux CB. 1994. Mesalazine during pregnancy. Lancet 344(8938):1708-1709.
  • Moskovitz DN, et al. 2004. The effect on the fetus of medications used to treat pregnant inflammatory bowel-disease patients. Am J Gastroenterol 99(4):656-661.
  • Nelis GF. 1989. Diarrhoea due to 5-aminosalicylic acid in breastmilk. Lancet 1:383.
  • Shin T et al. 2014. Inflammatory bowel disease in subfertile men and the effect of mesalazine on fertility. Syst Biol Reprod Med 60(6); 373-376.
  • Silverman DA et al. 2005. Is mesalazine really safe for use in breastfeeding mothers? Gut 54: 170-1.
  • Xu YL, et al. 2017. Inflammatory bowel disease in pregnancy: A report of 7 cases and review of the literature. Int J Clin Exp Med; 10:5525-32.