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Mercury Toxicity

  • Cynthia M. Johnson, MA
Publication Type:


Mercury Toxicity

(Mercury Poisoning)


Mercury toxicity is when a person is exposed to high levels of mercury. Mercury is a naturally occurring heavy metal. Short or long term exposure to it can cause serious health problems.

Mercury has several forms, including:

  • Metallic mercury—a shiny, silver white, odorless liquid that becomes a colorless, odorless gas when heated
  • Methylmercury—a chemical made up of mercury combined with carbon, mainly made by microscopic organisms in the water and soil
  • Mercury salts—white powders or crystals formed when mercury combines with elements like chlorine, sulfur, or oxygen

Metallic mercury and methylmercury easily reach the brain and are more harmful than mercury salts.


Mercury toxicity happens when a person is exposed to high amounts of mercury from:

  • Breathing airborne mercury vapors
  • Eating contaminated food, especially certain fish and shellfish
  • Practicing religious or folk medicine rituals that include mercury
  • Drinking water contaminated with mercury (rare)

Metallic mercury can be found in consumer products like fluorescent light bulbs, batteries, thermostats, and old thermometers.

Mercury, combined with other elements, is also found in some types of dental fillings. Research has not shown that this type of filling is harmful to people.

Thimerosol is a preservative that was used in some vaccines in the US. It contains a very small amount of a type of mercury, but many studies have shown that it was not harmful to people.

Risk Factors

Anyone can develop mercury toxicity as a result of mercury exposure. Pregnant women, their unborn fetuses, and young children are at higher risk to the harmful effects.

Some people are more likely to be exposed to mercury, such as people who:

  • Work in:
    • Dental services
    • Health services
    • The chemical industry
    • Other industries that use mercury
    • Electric meter repair
  • Eat over 6 ounces of white albacore tuna per week
  • Eat over 12 ounces a week of fish and shellfish that is considered lower in mercury, such as shrimp, canned light tuna, salmon, pollock, and catfish
  • Practice rituals that include mercury


Mercury can cause harmful effects before symptoms happen. For this reason, people should contact their doctors if they think they have been exposed.

When symptoms do develop, they may include:

  • Redness of the arms, legs, chest, and nose
  • Nausea and vomiting
  • Diarrhea
  • Belly pain
  • Coughing
  • Peeling of the hands and feet
  • Pain in the arms and legs
  • Shaking
  • Changes in vision or hearing
  • Problems sleeping
  • Weakness
  • Memory problems
  • Headache
  • Rapid heartbeat and chest pain
  • Eye irritation
  • Irritability
  • Breathing problems
  • Mouth pain
  • Fever and chills
  • Problems with focus


The doctor will ask about symptoms and past health. A physical exam will be done.

Tests may be done to look for signs of high levels of mercury in the body. This can be done with:

  • Blood tests
  • Urine (pee) tests
  • Scalp hair analysis


The source of mercury exposure will need to be identified and stopped.

Mercury toxicity is treated with chelation therapy. This involves putting a chemical known as a chelating agent into the bloodstream. It combines with the mercury to help remove it from the body. Chelating agents may be given by pill or injection.


The risk of mercury toxicity may be lowered by:

  • Avoiding the use of metallic mercury for any purpose
  • Following safety precautions when doing jobs that require working with metallic mercury
  • Carefully handling and disposing of items containing mercury, such as thermometers and fluorescent light bulbs
  • Replacing old thermometers and other items that contain mercury with new ones that do not
  • Limiting fish intake to recommended quantities and avoiding fish known to be contaminated by mercury:
    • Eat up to 12 ounces of fish and shellfish considered lower in mercury per week. These fish include shrimp, canned light tuna, salmon, pollock, and catfish.
    • Do not eat shark, swordfish, king mackerel, or tilefish, especially during pregnancy.
    • Eat up to 6 ounces of white albacore tuna per week.

To clean up a small amount of spilled metallic mercury:

  • Remove children from the area.
  • DO NOT use a vacuum cleaner.
  • Carefully roll the bead of mercury onto a sheet of paper or suck it up with an eyedropper.
  • Place the bead in a bag or airtight container and contact the local health department to find out how to dispose of it.
  • Ventilate the room to the outside. Use fans for at least one hour.




  • Health effects of exposures to mercury. US Environmental Protection Agency website. Available at:
  • Mercury and your health. Agency for Toxic Substances and Disease Registry website. Available at:
  • Mercury levels in commercial fish and shellfish (1990-2012). US Food & Drug Administration website. Available at:
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.