Nausea Medications for Morning Sickness During Pregnancy

Is it safe to take medicine like promethazine while pregnant? Experts weigh in on the pros and cons of treating morning sickness with prescription drugs.

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Anyone who's ever dealt with morning sickness will tell you: It's no joke. And now medical experts are shedding a bit more light on the importance of adequately treating pregnancy-induced nausea.

According to Britain's Royal College of Obstetricians and Gynecologists (RCOG), four out of five pregnant people experience morning sickness through pregnancy and, despite its name, this affliction can strike all day, every day. The RCOG stresses the importance of proper treatment for morning sickness, which can include nausea medications for more severe cases.

Treating Morning Sickness With Medication

According to the RCOG's guidelines, there's a lack of understanding about morning sickness. While drug-free therapies like ginger and acupuncture can provide relief from morning sickness, experts recommend severe cases of morning sickness be treated with medicine or even hospital treatment.

"Women with persistent nausea can often feel that there is a lack of understanding of their condition," Dr. Manjeet Shehmar, the lead author of the guidelines, said, according to the BBC. "They may be unable to eat healthily, have to take time off work, and feel a sense of grief or loss for what they perceive to be a normal pregnancy. It is therefore vital that women with this condition are given the right information and support and are made aware of the therapeutic and alternative therapies available to help them cope."

Jonathan Schaffir, M.D., an associate professor in the department of Obstetrics and Gynecology at The Ohio State University College of Medicine, says morning sickness ranges from the occasional discomfort to a miserable experience with weight loss, dehydration, and inability to tolerate any food at all. "While the low end of this spectrum may be amenable to non-prescription treatments like bland foods and ginger, the more severe symptoms will usually require some help in the form of medication."

The American Congress of Obstetricians and Gynecologists (ACOG) agrees that treatment depends on the severity of the case. "If diet and lifestyle changes do not help your symptoms, or if you have severe nausea and vomiting [during] pregnancy, medical treatment may be needed," the group said in an emailed statement. "If other medical conditions are ruled out, certain medications can be given to treat nausea and vomiting. You and your obstetrician or other members of your health care team can discuss all of these factors to determine the best treatment for your personal situation."

Morning Sickness Medication Options

Dr. Schaffir says there are several anti-nausea medications that can be used in pregnancy for morning sickness. Here's some more information about the most common options.

Pyridoxine and doxylamine

"The most extensively studied medication that has been proven safe [during pregnancy] is a combination of vitamin B6 (pyridoxine) and doxylamine, which is available over the counter as a sleep aid," Dr. Schaffir says.

Your doctor will give instructions for the medicine, but you'll likely take it two-three times each day. Possible side effects include drowsiness, dry mouth, headaches, dizziness, gastrointestinal issues, muscle pain, and rash.


Dr. Schaffir says that other antihistamines, such as promethazine, are also safe during pregnancy. The prescription drug promethazine is sometimes used to treat nausea and vomiting (and it's also prescribed for allergies, motion sickness, and sleep regulation). Common side effects include drowsiness, double vision, nervousness, constipation, and hyperactivity, among others.

Promethazine was classified as a category C pregnancy drug. This means that adverse effects have appeared in animal testing, but there haven't been enough human studies to confirm any complications during pregnancy. Therefore you should only take promethazine while pregnant when the benefits outweigh the risks. Talk to your doctor for more information.


Many people don't like the sedative effects that nausea medications have, because they become too sleepy to work or take care of other children. A non-sedating medicine that is helpful for nausea in pregnancy is ondansetron. Side effects include headache, dizziness, constipation, and fatigue.

"While used widely with no bad effects, the use of ondansetron in the very early part of pregnancy has come under increased scrutiny lately because of conflicting reports that it may be associated with a small increase in the rate of certain birth defects," says Dr. Schaffir. "This association has by no means been proven, but because of the uncertainty, many caregivers will avoid this medication until after the first two months of pregnancy."

Regardless, he says that if a pregnant person is unable to keep any food or drink down, then the risk of complications of dehydration and insufficient nutrition may be greater than the risk of using this medication.

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