Selenium Side Effects

Selenium, a mineral found in soil, occurs naturally in a number of foods, including Brazil nuts, whole grains, sunflower seeds, seafood, etc. Your body cannot produce selenium on its own, but it needs selenium for proper thyroid and immune system function. It is important to provide your body with sufficient amount of selenium through food and supplements, but you need to pay attention to selenium side effects as well.

Selenium Benefits and Uses

Like mentioned, selenium is important for your bodily functions, and there are many important selenium uses as well.

The biggest highlight of selenium is that it has antioxidant properties that prevent any damage to your cells. Your body makes use of selenium to produce enzymes called selenoproteins. There are 25 of these enzymes, and some like peroxidases and glutathione work as antioxidants. These are basically molecules produced to prevent cell damage. These molecules also offer cellular protection by changing hydrogen peroxide and other chemicals into harmless products like water.

Many researchers have found that consuming up to 200mcg of selenium with thyroid hormone goes a long way in decreased antibodies that are directly associated with autoimmune thyroiditis. People who are already suffering from this condition may take selenium with thyroid hormone to improve mood.

Selenium also helps reduce your cholesterol. Some studies have confirmed that taking up to 200mcg of selenium supplement every day for 6 months will help lower your cholesterol levels. You can opt for any supplement, including Pharma Bord, SelenoPrecise or Denmark. You can also use these supplements to help get rid of several conditions, including arthritis, asthma, infertility, dandruff, and much more. However, the benefits of selenium have not been totally proved. So it is important to consult your doctor before you start taking selenium supplements to avoid selenium side effects.

Selenium Side Effects

Selenium is usually quite safe for most people when administered by mouth, but it is important to consume it in doses less than 400mcg a day. You only need to consume it for short-term or else it may lead to selenium toxicityand cause several issues. You should avoid taking higher doses as well and stop its use immediately if you notice the following side effects:

  • Vomiting and nausea
  • General feeling of being very tired
  • Feeling irritable
  • Mild rash, hair loss, painful fingernails with white streaks on them
  • Tremors and muscle tenderness
  • Redness, warmth or tingle feeling
  • Bad breath, metallic taste, or strong body odor
  • Easy bruising and bleeding

To avoid these side effects, you should never exceed the recommended dietary allowance of selenium.

Age (years old)

Recommended Dietary Allowance (micrograms/day)







Above 14

  • Ÿ   Pregnant women
  • Ÿ   Breastfeeding women


  • Ÿ   60mcg/day
  • Ÿ   70mcg/day

Precautions and Warnings for Selenium

You usually don't have to worry about selenium side effects when you take lower doses for a short time only, but there are certain precautions and warning signs you should look for if you're taking selenium supplements.

  1. Children: Selenium is general safe for children when administered orally. For different age group of children, the safe recommendation dose also changes.
  • Ÿ   Lower than 45mcg/day for infants up to 6 months of age
  • Ÿ   60mcg/day to infants between 7 and 12 months
  • Ÿ   90mcg/day to children between 1 and 3 years of age
  • Ÿ   150mcg/day to children between 4 to 8 years,
  • Ÿ   280mcg/day to children between 9 to 13
  • Ÿ   400mcg/day to children over 14 years of age
  1. Pregnancy and Breastfeeding: It is safe to use selenium during pregnancy and breast-feeding, but don't exceed 400mcg/day. Any selenium supplement above 400mcg might cause selenium toxicity.
  2. Autoimmune Diseases: Several experts are of the view that selenium can stimulate your immune system, so you shouldn't be taking it if you're suffering from an autoimmune disease such as systemic lupus erythematosus, multiple sclerosis or rheumatoid arthritis.
  3. Hemodialysis: Selenium levels will go down in blood if you're undergoing hemodialysis. It is a good idea to use a dialysis solution with selenium, but you may need to take selenium supplementation as well.
  4. Fertility Problems in Men: One of many selenium side effects is on your reproductive system. It may affect the ability of your sperm to move, which in turn will reduce fertility.
  5. Skin Cancer: Although it's controversial, the extended use of selenium supplement may increase the recurrence risk of skin cancer. Still, it is a good idea to avoid using these supplements if you have had skin cancer in the past.
  6. Under-active Thyroid: You may want to avoid selenium supplements if you're suffering from hypothyroidism. It is a good idea to avoid it altogether if you also have iodine deficiency.
  7. Surgery: You should avoid taking selenium supplements before and after your surgery because it can increase the risk of bleeding. You should stop using it at least a couple of weeks prior to undergoing a surgery.
  8. Interactions: It is important to know a bit about medicines that you should not be using with selenium supplements. Selenium may interact with supplements and medicines such as chemotherapy drugs, antacids, corticosteroids, birth-control pills and cholesterol-lowering statin drugs. So, never take them together.