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What Are Signs of Mercury Poisoning?
Updated on September 21, 2023
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At Home Health
What Are Signs of Mercury Poisoning?

The signs of mercury poisoning vary depending on several factors, but if you’ve been exposed to mercury, look out for:1

  • A metallic taste in your mouth
  • Coughing
  • Breathing difficulties 
  • Bleeding or swollen gums

If you think you might have ingested mercury, you may experience the following:1,2

  • Burning in your stomach and throat 
  • Nausea
  • Reddish urine

But remember, the symptoms of mercury poisoning can change depending on the type of mercury and how it got into your body.3

“Mercury often enters the body by inhalation into the blood, where it reaches other organ systems. While it’s liquid at room temperature, it can easily vaporize and enter your system,” explains our in-house medical expert, Dr. Rizza Mira.

What is Mercury Poisoning?

Understanding the Different Forms of Mercury

Mercury comes in different forms. While most of these forms are harmful to your health, they can cause different sets of symptoms.

Inorganic mercury comes in the form of mercury salts, which are used in batteries as well as in some medications.3,4

Organic mercury is formed when certain bacteria process inorganic mercury in the environment. This results in a substance called methylmercury. It accumulates in animals like fish and shellfish.3,5

Elemental mercury is also known as liquid mercury, and is commonly found in devices like thermometers.3

How Mercury Enters the Body

Ingestion is one of the main ways that mercury can enter the body. Usually, this happens when you eat seafood with methylmercury

Most people will not consume enough methylmercury through seafood. However, people who consume large amounts of fish run the risk. 

Certain types of fish tend to be richer in methylmercury. These are larger fish that prey on other fish, as the methylmercury from the prey fish passes on to the larger fish.

Industrial accidents can also release mercury into the ocean. When this happens, seafood in the area can be extremely high in methylmercury content. This causes widespread illness.5

When dealing with inorganic mercury, inhalation is also a risk. If you leave mercury or liquid mercury in the open, it can evaporate into mercury vapor.6

“Mercury absorbed through the skin creates higher levels of mercury in the blood because the skin is the largest organ system. Other factors that increase mercury levels are the duration of exposure, amount of mercury present, and consistency of exposure,” says Dr. Mira.

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Common Sources of Mercury Exposure

Seafood Containing Methylmercury

The most common way you could be exposed to methylmercury is by ingesting seafood containing large amounts of it.

Fish that eat smaller fish are more likely to have greater amounts of methylmercury. This is because the smaller fish pass on methylmercury to larger fish that eat them.

Cooking does not reduce the amount of methylmercury in food. This means methylmercury will also be ingested by anyone eating these fish.

But remember, most people eating a varied diet will not ingest enough methylmercury to have an effect on their health.5,6

“Mercury causes adverse reactions even to unborn fetuses when the mother eats large amounts of fish that are mercury-rich,” cautions Dr. Mira, reminding everyone to diversify their diet.

Environmental and Occupational Exposure

Of course, mercury mining carries a risk of mercury exposure. But other types of mining, like gold mining, also use mercury.

Medical waste disposal and coal burning also make use of significant amounts of mercury.7

Workers in manufacturing or chemical processing can also be exposed to mercury in the workplace.8

Dental Amalgam Fillings

Mercury can also be found in dental amalgam fillings, which are used to fill cavities in teeth. Liquid mercury is a significant component of these fillings. Because of this, these fillings can release small amounts of mercury vapor.

However, there is little evidence that these fillings have negative effects on human health.

The United States Food and Drug Administration (FDA) has approved these fillings. Anyone over six years of age can use them. The FDA also regulates these fillings to ensure they are fit for dental use.

 “Most studies conducted show that these dental amalgams have no significant effects on the health of the general population,” confirms Dr. Mira.

However, a wide variety of alternative dental fillings do not contain mercury. If you are hesitant to get a dental amalgam filling, be sure to discuss these other options with your dentist.9

Signs and Symptoms of Mercury Poisoning

Mercury poisoning can lead to a range of symptoms, depending on several factors.

First, the type of mercury you were exposed to is essential. For example, exposure to elemental mercury can lead to a different set of symptoms from organic mercury. 

You need to consider how you were exposed. Some symptoms are associated with inhaled mercury and others with ingested mercury.

Mercury poisoning can also present differently depending on the length of exposure. 

Chronic exposure means constant exposure to mercury over a long time. Acute exposure means exposure to a larger amount of mercury in a shorter time.3

Neurological Symptoms

Neurological symptoms of mercury poisoning include headache and visual disturbances. If you have inhaled mercury, you could also experience a metallic taste in your mouth.10

“Neurological symptoms are slow to develop but are most difficult to diagnose and treat,” says Dr. Mira.

Chronic mercury exposure can also lead to erethism. This results in depression, memory loss, or irritability.10

Erethism is also known as “Mad Hatter’s Disease.” It’s named after how hat makers used to use a form of mercury in their craft. This led to the expression “mad as a hatter” and inspired the Mad Hatter from Alice’s Adventures in Wonderland.10-12

Methylmercury toxicity, in particular, can lead to: 

  • Tingling in the hands, feet, and mouth
  • Issues with balance or coordination (called ataxia)
  • Issues with sight or hearing

Children are prone to the neurological effects of chronic organic mercury poisoning. These include learning disorders and ataxia.3

“There are no designated safe mercury levels in children yet. Thus, they should not be exposed to any level of mercury at all,” says Dr. Mira.

Respiratory Symptoms

Respiratory symptoms are common in cases of elemental mercury vapor inhalation.

“Elemental mercury is absorbed mostly in the lungs—about 80%,” explains Dr. Mira. 

Usually, these symptoms include cough and shortness of breath. 

In severe cases of mercury inhalation, people can experience respiratory distress. This is a potentially deadly condition.3,10

Skin Reactions

Mercury toxicity can sometimes result in rashes

One notable skin reaction is acrodynia. It is a condition resulting from chronic mercury exposure. It leads to painful, pink rashes on the palms or soles of the feet.

Skin reactions can also take the form of contact dermatitis.10

Gastrointestinal Issues

Gastrointestinal issues can be common in cases of inorganic mercury exposure. This is because inorganic mercury is usually ingested.

If you suffer from this, you might experience nausea or abdominal pain. It can also cause you to vomit or vomit blood.3,10

Muscular and Joint Pain

Acrodynia from chronic mercury exposure can also result in weakness and reduced muscle strength.10

“Aside from organ systems, mercury poisoning can affect the cardiovascular, renal, and motor systems,” explains Dr. Mira.

How is Mercury Poisoning Diagnosed?

It can be difficult to diagnose mercury poisoning. Its symptoms can also be associated with other unrelated conditions.

Your doctor might also ask for other tests, including blood tests, a urine test, or imaging tests like X-rays.3

Medical History and Physical Examination

If you see a doctor about possible mercury toxicity, they will take a detailed medical history. This will help them determine when and how you might have been exposed to mercury.

This is because some types of mercury toxicity will only show symptoms weeks or months after exposure.

They will also perform a physical exam to look for signs of mercury exposure. This will also rule out other potential causes of your symptoms. Your doctor may also test for other heavy metals to rule out other types of heavy metal poisoning.3

Blood, Urine, and Hair Testing

One way to diagnose mercury poisoning is by using blood tests.

Levels of mercury in the blood will usually be very high after acute exposure

However, blood tests are less useful in people with chronic exposure to methylmercury. The amount of mercury in the blood is not always elevated in these people.

“Ideally, mercury levels in every organ system are taken. However, this is very difficult and often expensive,” says Dr. Mira.

Similarly, mercury can exit the body through urine, so urine tests are also a good way to diagnose mercury poisoning. However, urine tests are not helpful for diagnosing methylmercury exposure. 

Hair can also be used to diagnose mercury poisoning. This is because certain substances in the hair attract metal particles like mercury.

The mercury concentration in your hair can be used to determine if you are suffering from mercury poisoning. Unlike blood and urine tests, hair tests can also be used to diagnose methylmercury exposure.13

Testing hair is most useful for anyone who has experienced chronic exposure to mercury.

Treatment Options for Mercury Poisoning

If you are exposed to mercury, you should seek medical attention. In cases of mercury vapor inhalation, get away from the source of mercury as soon as possible and try to get to an area with fresh air.14

Removal of Mercury Sources

The most urgent aspect of treating mercury poisoning is dealing with the source of mercury. This means removing a person from the site of mercury exposure. It also includes identifying sources of chronic mercury exposure.3

Supportive Care and Symptom Management

If you go to the hospital for mercury toxicity, the doctors might also give you supportive care. This depends on the severity of your symptoms. Their priority is to establish functional airways, breathing, and circulation. They could also use an oxygen mask or intravenous fluids.1

Chelation Therapy

Chelation therapy is an essential procedure used to treat mercury poisoning. In chelation therapy, doctors give you drugs called chelators. They bind to mercury particles in your body to remove them. This process can last weeks or months after exposure.1

Preventing Mercury Poisoning

When it comes to dealing with mercury, prevention will always be preferable to treatment

There are some good ways to prevent mercury poisoning. This is important if you are pregnant.

“Mercury is passed in a woman’s placenta and is even present in breastmilk,” explains Dr. Mira.

Mercury exposure during pregnancy can adversely affect the fetal brain and cognitive development. This results in potential issues after birth.10

Choosing Low-Mercury Fish and Seafood

Seafood is a major source of mercury, though most people will not be affected by the amount of mercury in the fish they eat. If you are trying to avoid mercury exposure, there are still many types of seafood that are low in methylmercury content.15

Low-mercury seafood include:15

  • Anchovy 
  • Black sea bass 
  • Haddock 
  • Salmon 
  • Freshwater trout 
  • Clam 
  • Crawfish 
  • Lobster 
  • Oyster 
  • Shrimp 
  • Squid

Seafood high in mercury include:15

  • King mackerel 
  • Marlin 
  • Orange roughy 
  • Shark 
  • Swordfish 
  • Bigeye tuna

Reducing Occupational Exposure

If your workplace makes use of mercury, there are ways you can reduce your exposure to mercury.

Perform regular maintenance on all instruments or machines involved in your work with mercury.

Education is also key to avoiding unnecessary mercury exposure. Familiarize yourself with the properties of any dangerous chemicals you use. Attend relevant training sessions on the proper use of substances like mercury.16

Safe levels of mercury are required to be outlined for every industry that is exposed to mercury. These should be followed and monitored.

Safe Handling and Disposal of Mercury-containing Products

Always wear appropriate safety gear or personal protective equipment when dealing with mercury. This includes gloves, aprons, boots, and eye protection. An appropriate respirator should be used if you are dealing with mercury vapor. 

When disposing of mercury, the waste should be clearly labeled and separated from other types of waste. Liquid mercury should be stored in leak-proof containers and should never be flushed down a toilet.16

Long-term Effects and Prognosis of Mercury Poisoning

The prognosis and long-term effects of mercury poisoning depend on how and how long you were exposed to mercury

If you were only exposed for a short time or to a small amount, you can expect to make a full recovery. However, chronic or severe exposure can have lifelong effects and can potentially be deadly.3

Potential Health Complications

The effects of organic mercury toxicity are thought to be permanent. These can include erethism and ataxia.

Mercury exposure during pregnancy can also result in fetal complications. This can lead to permanent disabilities. These include physical deformities, learning disorders, cognitive impairments, deafness, and possibly death.3,10

Recovery and Follow-up Care

Follow-up care for mercury toxicity usually includes chelation therapy. This sometimes needs weeks or months to be fully effective. If you were only exposed to a small amount of mercury, you should recover completely over time.1,3,10

However, the neurological effects of mercury poisoning are thought to be permanent.3,10

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Updated on September 21, 2023
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16 sources cited
Updated on September 21, 2023
  1. Mercury Poisoning.” Cleveland Clinic. 
  2. Urine Changes.” Cleveland Clinic.
  3. Posin, SL, et al. “Mercury Toxicity.” StatPearls. 13 Aug. 2022.
  4. What Do You Know About Mercury?” New York State Department of Environmental Conservation. 
  5. Mercury and Health.” World Health Organization.
  6. How People are Exposed to Mercury.” US Environmental Protection Agency. 
  7. Mercury in the Environment.” United States Geological Survey.
  8. Mercury.” The National Institute for Occupational Safety and Health.
  9. Mercury in Dental Amalgam.” US Environmental Protection Agency.
  10. Rusyniak, DE, et al. “Heavy metal poisoning: management of intoxication and antidotes.” Molecular, Clinical and Environmental Toxicology. 2010.
  11. O’Carroll, RE, et al. “The neuropsychiatric sequelae of mercury poisoning. The Mad Hatter's disease revisited.” The British Journal of Psychiatry. Jul. 1995. 
  12. NIOSH Backgrounder: Alice's Mad Hatter & Work-Related Illness.” Centers for Disease Control and Prevention.
  13. Ye, B, et al. “Evaluation of mercury exposure level, clinical diagnosis and treatment for mercury intoxication.” Annals of Occupational and Environmental Medicine. 22 Jan. 2016.
  14. Chemical Profiles: Mercury.” Canadian Centre for Occupational Health and Safety.
  15. Advice about Eating Fish.” US Food and Drug Administration.
  16. Exposure to Mercury in the world of work: A review of the evidence and key priority actions.” International Labour Organization.
Dr. Rizza Mira
Dr. Rizza Mira
Medical Reviewer
Dr. Rizza Mira is a medical doctor and a general practitioner who specializes in pediatrics, nutrition, dietetics, and public health.

As a pediatrician, she is dedicated to the general health and well-being of children and expecting parents. She believes that good nutrition, a healthy lifestyle, and prevention of illness are key to ensuring the health of children and their families.

When she’s not in the hospital, Rizza advocates and mobilizes causes like breastfeeding, vaccination drives, and initiatives to prevent illness in the community.
Will Hunter
Will Hunter
Content Contributor
Will is a content writer for KnowYourDNA. He received his B.A. in Psychology from the University of California, Los Angeles. Will has 7 years of experience writing health-related content, with an emphasis on nutrition, alternative medicine, and longevity.
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