Merck Manual

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Selenium Excess

By

Larry E. Johnson

, MD, PhD, University of Arkansas for Medical Sciences

Reviewed/Revised Jul 2023 | Modified Aug 2023
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Selenium excess is rare and is caused by consuming too much of the mineral selenium.

Selenium occurs in all tissues. Selenium works with vitamin E as an antioxidant. It helps protect cells against damage by free radicals, which are reactive by-products of normal cell activity. Selenium may help protect against some cancers. Selenium is also necessary for the thyroid gland to function normally.

Taking more than 900 micrograms of a nonprescription selenium supplement each day can have harmful effects. Symptoms of selenium toxicity are mainly gastrointestinal upset, including nausea, vomiting, and diarrhea. Other symptoms include hair loss, abnormal nails, a rash, fatigue, and nerve damage. The breath may smell like garlic.

The diagnosis of selenium excess is based on symptoms. Blood or urinaryselenium levels can be measured.

Treatment of selenium excess involves reducing selenium consumption.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Alph-E-Mixed , AQUA-E, Aquasol E , Aquavite-E
Selepen
No brand name available
NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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