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Is selenium safe during pregnancy?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

NIH lists 60 mcg of selenium a day for pregnancy and an upper limit of 400 mcg, while EFSA set 255 mcg for all adults, pregnant women included. Trials in women with thyroid antibodies gave mixed results, and the American Thyroid Association weakly recommends against supplements for them. Ask your doctor before taking selenium.1,2,3

Key facts

  • NIH lists 60 mcg of selenium a day in pregnancy, against 55 mcg for other adults, and says most people in the United States get enough from food.1
  • The upper limit is 400 mcg a day from all sources for pregnant teens and adults, and EFSA's 2023 opinion set 255 mcg for adults including pregnant women.1,3
  • In pregnant women with thyroid antibodies, one trial of 200 mcg a day found fewer postpartum thyroid problems, while another trial of 60 mcg a day found no effect on antibodies.2,4,5
  • The American Thyroid Association made a weak recommendation against selenium supplements for pregnant women with thyroid antibodies.2
  • Brazil nuts hold 68 to 91 mcg of selenium each, so nuts and supplements can add up.1

How much selenium does NIH list for pregnancy?

The recommended amount rises to 60 mcg a day in pregnancy and 70 mcg a day while breastfeeding.1

Most people in the United States get enough selenium from the foods they eat, and selenium deficiency is very rare in the United States and Canada.1

NIH adds that Brazil nuts hold 68 to 91 mcg of selenium each and can take a person over the upper limit if eaten in quantity. Food, drinks and supplements all count toward that limit.1

What upper limit applies during pregnancy?

The upper limit for selenium is 400 mcg a day for adults and teens 14 and older, including during pregnancy and breastfeeding, counting food, drinks and supplements together. It is lower for children: 90 mcg at ages 1 to 3, 150 mcg at 4 to 8 and 280 mcg at 9 to 13. The limits do not apply when a doctor is giving selenium.1,2

EFSA took a more cautious view. Its 2023 opinion set one limit of 255 mcg a day for all adults, including pregnant and lactating women, based on hair loss that a large trial saw at 330 mcg a day.3

NIH says the most common signs of too much selenium are hair loss and brittle or lost nails, with garlic breath and a metallic taste as earlier clues.2

What did trials in pregnant women find?

NIH describes three trials in pregnant women who had thyroid peroxidase antibodies, a marker of autoimmune thyroid activity. In one, 151 women took 200 mcg a day of selenomethionine from 12.5 weeks of pregnancy to 12 months after birth. Postpartum thyroid disorders were found in 28.6% of the selenium group and 48.6% of the placebo group, and permanent underactive thyroid in 11.7% against 20.3%.2,4

A second small trial gave 83 mcg a day and also found lower antibodies at 6 months after the birth. A third gave 60 mcg a day of selenium yeast to women with mild to moderate iodine shortage and found no drop in antibodies at delivery.2

A UK trial in 230 pregnant women, with and without thyroid antibodies, gave 60 mcg a day until delivery. Selenium did no better than placebo at lowering antibodies, and in women who were antibody-positive at the start, free thyroxine was lower than on placebo at 35 weeks.5

After weighing this evidence, the American Thyroid Association made a weak recommendation in 2017 against selenium supplements for pregnant women with thyroid antibodies, based on moderate-quality evidence. NIH says more research is needed.2

What about selenium sulfide shampoo, and zinc with selenium?

NIH's fact sheets cover selenium as a nutrient, not selenium sulfide. The over-the-counter dandruff shampoo label read for this page says it is for external use only, to ask a doctor before use if the condition covers a large area of the body, and to stop use and ask a doctor if it worsens. It does not mention pregnancy.6

The sources checked do not rule on zinc and selenium taken together in pregnancy. NIH's limit for selenium counts every source, so a person using a prenatal vitamin, a zinc product and nuts should add up all the labels and ask a doctor or pharmacist.1,2

Who should ask a doctor about selenium in pregnancy?

  • Anyone who is pregnant and has a thyroid condition or thyroid antibodies.2
  • Anyone already taking a prenatal or multivitamin that lists selenium, or eating Brazil nuts often.1
  • Anyone considering a selenium-only product. NIH says these usually hold 100 to 400 mcg, against 55 mcg in many multivitamins.2
  • Anyone having chemotherapy with cisplatin, which can lower selenium levels.1

Ask your doctor, and bring every label so the selenium in each product can be added up.

Questions people ask

Is selenium supplement safe during pregnancy?

NIH lists 60 mcg a day for pregnancy and 400 mcg as the upper limit, EFSA sets 255 mcg, and trials in women with thyroid antibodies were mixed. Ask your doctor before taking a selenium supplement.1,2,3

Is selenium sulfide shampoo safe during pregnancy?

The over-the-counter shampoo label read for this page does not mention pregnancy and says to ask a doctor before use if the condition covers a large area. NIH's selenium sheets do not cover selenium sulfide, so ask your doctor or pharmacist.6

Is zinc and selenium safe during pregnancy?

The sources checked do not address the pair. NIH's 400 mcg selenium limit counts food and supplements together, so add up every label and ask your doctor or pharmacist.2

Is selenium OK for pregnancy?

NIH lists 60 mcg a day as the pregnancy need and says most people in the United States get enough from food. Ask your doctor before adding a supplement, especially with thyroid antibodies or a thyroid condition.1,2

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Sources

  1. Office of Dietary Supplements, National Institutes of Health. Selenium: Fact Sheet for Consumers. Updated June 18, 2025. Opened 2026-10-07.
  2. National Institutes of Health, Office of Dietary Supplements. Selenium: Fact Sheet for Health Professionals. Updated September 4, 2025. Opened 2026-10-07.
  3. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, et al. Scientific opinion on the tolerable upper intake level for selenium (opinion built on systematic reviews of the literature). EFSA J. 2023;21(1):e07704. Opened 2026-10-11.
  4. Negro R, Greco G, Mangieri T, Pezzarossa A, Dazzi D, Hassan H. The influence of selenium supplementation on postpartum thyroid status in pregnant women with thyroid peroxidase autoantibodies. A randomized, placebo-controlled trial. J Clin Endocrinol Metab. 2007;92(4):1263-1268. Opened 2026-10-11.
  5. Mao J, Pop VJ, Bath SC, Vader HL, Redman CW, Rayman MP. Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency. A randomized trial (secondary analysis of SPRINT). Eur J Nutr. 2016;55(1):55-61. Opened 2026-10-11.
  6. Dandruff (selenium sulfide) shampoo: product label (H-E-B). DailyMed, U.S. National Library of Medicine. Effective February 24, 2026. Opened 2026-10-11.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.