Many pregnant women take vitamin B-6 and Unisom to treat morning sickness. In the past, some people had concerns that this combination may harm the fetus.

Morning sickness is very common during early pregnancy. Although people often refer to nausea and vomiting during pregnancy as “morning sickness,” it can actually happen at any time of the day or night.

The symptoms of morning sickness usually disappear by the beginning of the second trimester, but for some women, they can continue right up until delivery.

Unisom is the brand name of a sleeping drug called doxylamine. Diclegis is a delayed-release combination of doxylamine and pyridoxine, which is a form of vitamin B-6. According to a 2014 overview, the Food and Drug Administration (FDA) approved Diclegis in 2013 for the treatment of nausea and vomiting in pregnancy.

In this article, we discuss whether it is safe to take Unisom and vitamin B-6 for morning sickness during pregnancy. We then explore how this combination works, how to use it, and its possible side effects. We also explain what morning sickness is and provide some tips for managing the symptoms.


<img src="" alt="Pregnant woman taking unisom and b6 for morning sickness“>
Morning sickness symptoms may continue until delivery.

Unisom is a brand name for doxylamine, which is a sedating antihistamine that can help with sleeping difficulties. For many years, some women have used Unisom in combination with vitamin B-6 supplements to treat the symptoms of morning sickness.

Diclegis is a prescription medication that contains doxylamine and pyridoxine, a form of vitamin B-6. This combination drug is the only medication that the FDA have approved for treating nausea and vomiting during pregnancy.

The combination of vitamin B-6 and doxylamine was originally available between 1956 and 1983 under the brand name Bendectin. However, people filed several lawsuits in the 1970s alleging that Bendectin caused congenital disabilities.

Despite the lack of scientific evidence to support these lawsuits, in 1983, the manufacturer withdrew Bendectin from the market in the United States due to high insurance premiums.

However, many studies, including two meta-analyses, have demonstrated the safety of taking a combination of doxylamine and pyridoxine during pregnancy, finding no link to congenital disabilities. In fact, researchers have studied the safety of this drug combination in more than 200,000 pregnant women, which means that it has undergone more testing than any other drug for use during pregnancy.

The American College of Obstetricians and Gynecologists (ACOG) state that it is safe for women to take vitamin B-6 and doxylamine, either separately or as Diclegis, during pregnancy and that this combination has “no harmful effects on the fetus.”

How does it work?

Researchers are uncertain how the combination of vitamin B-6 and doxylamine works to treat morning sickness. This drug combination may act on neurotransmitters in the brain that trigger feelings of nausea or disrupt other bodily processes that cause vomiting.

Randomized controlled trials generally show that combinations of vitamin B-6 and doxylamine are effective in treating symptoms of morning sickness.

How do women use this treatment?

The ACOG recommend that women first try dietary and lifestyle interventions to treat morning sickness. If these interventions do not work or the symptoms are severe, they suggest trying vitamin B-6.

If vitamin B-6 does not provide symptom relief, a woman may wish to try doxylamine too. The ACOG state that a person can take these drugs separately or as the combination drug Diclegis. However, Diclegis is a prescription drug, and the cost may be prohibitive for some people.

According to the American Academy of Family Physicians, for treating morning sickness, women should take:

  • 10 to 25 milligrams (mg) of vitamin B-6 every 8 hours
  • 25 mg of doxylamine (Unisom SleepTabs) at night

For Diclegis, the manufacturers recommend that women take two tablets daily at bedtime. If symptoms do not improve, they suggest increasing the dose to three or four tablets, taking the extra ones in the morning and mid-afternoon.

Side effects

Unisom tablet which is a sleeping aid
A pregnant person should consult a doctor before taking Unisom, which is a sleeping aid.
Image credit: Dysamoria from USA, 2007

Drowsiness is a common side effect of taking doxylamine or Diclegis.

Other possible side effects of taking vitamin B-6 and doxylamine can include:

People who experience severe or concerning side effects should stop taking vitamin B-6 and doxylamine and consult their doctor.

What is morning sickness?

Morning sickness is one of the most common symptoms during early pregnancy. Although many women feel sick during a specific time of day, such as in the morning, others may experience this symptom at any time.

Doctors do not fully understand what causes morning sickness, but hormonal and blood glucose changes may play a role.

The symptoms of morning sickness are often relatively mild and will usually not harm the fetus. However, if a woman is unable to keep down food and fluids, this could put the fetus at risk. Any woman who is concerned about nausea and vomiting during pregnancy should see her doctor or obstetrician.

Up to 3 percent of pregnant women develop hyperemesis gravidarum, which is a more severe form of morning sickness. Doctors diagnose a woman with this condition when she loses more than 5 percent of her prepregnancy weight and has symptoms of dehydration.

Women with hyperemesis gravidarum may require medical treatment or hospitalization.

Tips for managing morning sickness

Some dietary and lifestyle interventions may help reduce or prevent morning sickness.

Strategies that a woman may wish to try include:

  • drinking plenty of fluids throughout the day
  • sucking on ice chips or popsicles
  • not drinking and eating at the same time
  • taking a multivitamin dietary supplement
  • eating small meals throughout the day rather than three large meals
  • keeping some plain crackers in the bedroom and eating them before getting out of bed in the morning
  • eating bland foods or trying the “BRATT diet,” which consists of bananas, rice, applesauce, toast, and tea
  • avoiding unpleasant odors
  • trying foods or drinks that contain real ginger, such as ginger candies, ginger tea, and ginger ale


Unisom is the brand name for a sleeping aid called doxylamine. Many women take a combination of doxylamine and vitamin B-6 to help treat morning sickness during pregnancy. These two medications are also available as a combination prescription drug called Diclegis.

In the past, there were concerns about the safety of taking doxylamine and vitamin B-6 while pregnant. However, numerous studies have demonstrated the safety of this drug combination, and there is little evidence to suggest that it can harm the fetus.

Experts generally recommend that women try dietary and lifestyle changes for managing morning sickness before taking medications. Women who are unable to keep down food and fluids or have concerns about nausea and vomiting during pregnancy should see their doctor or obstetrician.