Vitamin B6 is the first medicine the American College of Obstetricians and Gynecologists (ACOG) suggests trying for nausea and vomiting in pregnancy. It’s inexpensive, sold without a prescription, and has been found safe for the baby.

The short version

  • What works first: Vitamin B6 alone, or B6 combined with doxylamine (an ingredient in some over-the-counter sleep aids), according to ACOG.
  • Typical dose: 10 to 25 mg of B6, three or four times a day. Check with your provider before you start, and count the B6 already in your prenatal vitamin.
  • Don’t wait it out if it’s wearing you down: Treating early can keep symptoms from becoming severe. Whether to treat depends on how much it affects your life, not on whether someone calls it mild.
  • Call your provider if you can’t keep food or fluids down, you’re losing weight, or the nausea starts after 9 weeks or comes with pain or fever.

How common it is, and what to expect

Nausea is one of the most common parts of early pregnancy. Up to 80% of pregnant women have nausea, and about half have vomiting, according to ACOG’s clinical guidance. Despite the name “morning sickness,” it can happen at any time of day.

Timing. It usually starts before 9 weeks of pregnancy. For most women it fades by 14 weeks, though some have it for several more weeks or months, and a few for the whole pregnancy.

Effect on the baby. Nausea and vomiting usually don’t harm you or your baby, and they don’t mean something is wrong. The concern comes when you can’t keep down food or fluids and start losing weight. That can affect the baby’s birth weight and cause problems with your thyroid, liver, and fluid balance.

Who is more likely to have it severely. ACOG lists these risk factors:

  • Being pregnant with twins or more
  • Nausea and vomiting in a past pregnancy
  • A mother or sister who had severe nausea in pregnancy
  • A history of motion sickness or migraines
  • Being pregnant with a girl

What the research says about B6

Vitamin B6 (also called pyridoxine) has been the main recommended medicine for pregnancy nausea for decades. ACOG calls B6 alone, or B6 with doxylamine, a safe and effective first-line treatment.

ACOG suggests a step-by-step approach:

  1. Try B6 by itself first. It’s sold over the counter.
  2. Add doxylamine if B6 alone isn’t enough. Doxylamine is an antihistamine found in some over-the-counter sleep aids, so it can make you drowsy.
  3. Ask about the prescription version. A prescription pill that combines B6 and doxylamine is also available. It’s usually taken at bedtime.
  4. Move to other anti-nausea medicines if needed. If B6 and doxylamine don’t work, your provider can prescribe other medicines. Many have been shown to be safe in pregnancy; others have less safety information, so the choice depends on your situation.

According to ACOG, B6 and doxylamine, taken alone or together, have been found safe during pregnancy with no harmful effects on the baby.

What it won’t do. B6 can make nausea easier to live with, but it may not stop it completely. If it isn’t helping enough, that’s a reason to go back to your provider, not to push through.

How much B6, and how much is too much

The dose used for nausea is far higher than your daily need, so it’s worth adding up everything you take. Pregnant women need 1.9 mg of B6 a day from food and vitamins, according to the NIH. The nausea dose ACOG describes is 10 to 25 mg, three or four times a day.

Measure Amount per day
Daily need in pregnancy 1.9 mg
ACOG nausea dose (low end) 30 mg (10 mg, 3 times)
ACOG nausea dose (high end) 100 mg (25 mg, 4 times)
Upper limit, ages 19 to 50 100 mg
Upper limit, ages 14 to 18 80 mg

The upper limit counts B6 from all sources, including food and your prenatal vitamin. So the top of the nausea range, plus the B6 in a prenatal, can put you over it. That’s one reason to agree on a dose with your provider rather than guessing.

Why the limit matters. Taking high doses of B6 from supplements for a long time can damage nerves, according to the NIH. The nausea doses are meant for the weeks you need them, under a provider’s care.

Keep taking your prenatal. Don’t stop your prenatal vitamin to make room for B6 without talking to your provider. Folic acid matters most in these same early weeks.

Other things that help

Diet and routine changes are often enough for mild nausea, and they work alongside B6. You may need to try more than one. ACOG suggests:

  • Eat dry toast or crackers before you get out of bed, so you aren’t moving around on an empty stomach.
  • Eat small meals often instead of three large ones.
  • Try bland, low-fat foods like bananas, rice, applesauce, toast, and tea.
  • Sip fluids throughout the day.
  • Stay away from smells that set you off.
  • Try ginger: ginger ale made with real ginger, tea made from fresh grated ginger, ginger candies, or capsules. The evidence for ginger is weaker than for B6, but ACOG lists it as an option.

Protect your teeth. Stomach acid from frequent vomiting can wear away tooth enamel. Rinsing with a teaspoon of baking soda in a cup of water afterward can help neutralize it.

Planning a pregnancy? Taking a daily vitamin around the time you conceive may make nausea less severe, according to ACOG. That’s one more reason to start a prenatal vitamin early.

When it’s more than morning sickness

A small share of women develop hyperemesis gravidarum, the most severe form of pregnancy nausea, which needs medical treatment. It affects up to 3% of pregnancies. It’s often diagnosed when a woman has lost 5% of her pre-pregnancy weight and has signs of dehydration, according to ACOG. Treatment can include fluids and vitamins through an IV, other medicines, and sometimes a hospital stay.

Call your provider if:

  • You can’t keep down food or fluids
  • You’re losing weight
  • The nausea and vomiting start for the first time after 9 weeks of pregnancy
  • You have belly pain or tenderness, fever, or a headache along with the vomiting
  • You notice swelling in the front of your neck

The last three can be signs of another condition, such as an ulcer, food poisoning, thyroid disease, or gallbladder disease. Your provider will want to rule those out.

You don’t need to reach any of these points to ask for help. If nausea is making it hard to work, eat, or get through your day, that’s reason enough to bring it up.

Related reading

Sources

This article is for general information and is not a substitute for advice from your health care provider.