Is it pregnancy or your supplement making you sick? Find out how to prevent prenatal vitamin side effects like nausea. 

By Diana McKeon Charkalis
October 05, 2005
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woman taking prenatal vitamins side effects
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Women in their first trimester of pregnancy are most likely to experience morning sickness—a symptom compounded by the fact that prenatal vitamins can cause nausea too. Which leaves some queasy-stomached moms-to-be wondering, How bad is it if I occasionally skip my prenatal?

Although expectant women with very healthy eating habits may be able to forgo their vitamin here and there without major ramifications, it's better to find a way to make supplements more palatable, says Miriam Erick, a senior perinatal dietitian at Brigham and Women's Hospital in Boston and the author of No More Morning Sickness: A Survival Guide for Pregnant Women.

Try taking your daily supplement with something slippery you can stomach, like applesauce, suggests Erick. Never take your vitamin on an empty stomach, which can worsen nausea. "You can also try taking vitamins with lemonade or one of what I call the 'friendly' juices: creamy, smooth juice drinks like an orange-banana combo," Erick says. Just make sure it doesn't contain added sugar.

A third option is to take your supplement at a different time of day. Some women have the best luck at night, Erick says. Or try cutting it in two and taking half in the morning and half at night.

Or try another brand: vitamins vary in size, smell, and taste, and one brand might go down easier than another. "I always tell patients 'Buy a small quantity. Try them. See how you feel. Make sure you're not burping up fish and it's not killing your day, and then continue,'" says Julie Levitt, M.D., an ob-gyn at Women's Group of Northwestern in Chicago.

As a last-ditch effort, Erick advises trying kids' chewable vitamins with folic acid, a crucial vitamin for fetal brain and spine development. "Although they have lower dosages," she says, "something is better than nothing."

Taking too much of a particular vitamin can cause serious side effects, but it's rare if you're otherwise maintaining a healthy diet. "There's not much risk in over-supplementing, per se, because a lot of these are fat-soluble vitamins, so they just go into your stores; they don't poison the baby," says Dr. Levitt.

But (and this is a big but) there are a few vitamins that you definitely don't want to overdo it on—chiefly vitamin A, which can cause birth defects in high levels. Avoid supplements with more than 100 percent of the recommended dietary allowance of vitamin A, says Dr. Levitt. Most women won't get near a toxic amount, but watch out for other supplements or herbal remedies, which could contain vitamins that aren't listed under a name you'd recognize, says Scott Sullivan, M.D., the director of maternal-fetal medicine at Medical University of South Carolina.

Additionally, some studies have linked excessive folic acid to asthma, heart problems, cancer, and ectopic pregnancy. A 2014 study published in the Journal of Epidemiology & Community Health found that women who took folic acid supplements were twice as likely to die of breast cancer. Some women have a harder time absorbing the synthetic folate, or folic acid, found in prenatal vitamins, which may increase their risk of miscarriage.

You need a vitamin you're comfortable with since you won't necessarily stop taking it after your baby arrives. Most doctors advise continuing on prenatal vitamins for the duration of breastfeeding, or longer if you want to have another baby soon. When in doubt, ask your doctor about your prenatal vitamin and any other supplements you're taking.