7 common mercury poisoning symptoms

Medically reviewed by Neka Miller, PhD on January 21, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Ideally, you should have no mercury in your body, but small amounts—which usually from your diet—pose no true problems. However, in some cases, mercury can accumulate in the body over time and result in chronic mercury poisoning—posing a serious threat to one’s health. So what mercury poisoning symptoms should one keep an eye out for? Keep reading to learn more about some common mercury poisoning symptoms.


What causes mercury poisoning?

How do you get mercury poisoning? Eating fish as part of one's diet is the main way people in the United States are exposed to mercury. That's because trace amounts of mercury are present in bodies of water—such as lakes, rivers, and oceans—and mercury levels can build up over time in different kinds of fish (as well as shellfish).

Generally speaking, fish consumption is a healthy dietary choice, but frequently eating seafoods containing relatively high amounts of mercury can put you at a greater risk of mercury poisoning. Fish like shark, swordfish, tile fish, and king mackerel are known to have a high mercury content—so not eating these kinds of fish can help limit the mercury entering your body. On the other hand, seafood like anchovies, crawfish, herring, salmon, and trout have a very low mercury content.

Fish consumption, however, isn't the only possible source of mercury poisoning. Use of certain consumer and medical products, and specific occupations, can come with a higher risk of mercury exposure.

A select number of consumer products, such as fluorescent light bulbs and older thermometers, contain small amounts of liquid mercury. If these products accidentally break, the mercury can escape the container and evaporate—turning into a toxic (but invisible) gas. Exhaling this gas can contribute to mercury toxicity. (For more information, see the Environmental Protection Agency’s List of Common Consumer Products that Contain Mercury.)

Dental fillings, or dental amalgam (popularly known as "silver filling"), are another potential source of mercury exposure as this type of filling contains a small amount of liquid mercury. In the vast majority of cases, however, proper use of dental amalgam does not pose a serious health risk.

Exposure to mercury is also an occupational hazard in some industries. In particular, those who work in chemical processing facilities involving mercury or where electrical equipment or automative parts are made face a higher risk of mercury exposure.

The symptoms of mercury poisoning

Accumulating high levels of mercury in the body is often a slow process that can occur over a period of months or years, contributing to various downstream health effects. Similar to arsenic, iodine, and cadmium poisoning, that slow onset means that most people do not immediately realize that they are experiencing mercury poisoning. That being said, here are some symptoms that can give a clue to mercury toxicity:

1. Broad neurological symptoms

Organic mercury acts as a neurotoxin, meaning that it can drastically affect your central and peripheral nervous systems. This can lead to varying symptoms involving your cognition. This can include trouble thinking or processing thoughts, as well as sudden memory problems. The effect on the nervous system can also inhibit the senses, leading to:

  • Sudden vision changes (particularly a loss of peripheral vision)
  • Impaired speech and hearing
  • Numbness or a “pins and needles” sensation in the face and extremities

2. Seizures

Along with the above neurological symptoms, severe or chronic mercury poisoning may also increase the risk of seizures. Seizures are characterized by sudden electrical disturbances in the brain. While many people associate seizures with sudden uncontrollable jerking in the arms and legs, it also has much subtler symptoms, including:

  • Temporary confusion
  • A sudden loss of consciousness or awareness
  • Staring spells
  • A sudden sense of fear, anxiety, déjà vu, and other cognitive and emotional symptoms

3. A loss of fine motor skills

The damage to the brain and nerves can naturally extend to problems with fine motor skills. This can manifest in a sudden lack of basic coordination, like not being able to walk or move properly. You may experience uncontrollable shaking or tremors. Your muscles may also feel weak or unsupportive, or they may ache regardless of physical activities performed.

4. Mood changes and behavioral symptoms

Mercury intoxication may contribute to some severe mood and behavioral issues. People with mercury poisoning may experience greater irritability, or they may even suffer from previously undiagnosed depression and anxiety disorders. This can go even further into sudden bursts of anger, suicidal ideation, and obsessive-compulsive behaviors. These behavioral symptoms may come as a result of mercury’s damaging effects on the brain, which may fail to properly process or synthesize essential neurotransmitters linked to behavioral and mental health.

5. Kidney damage

When mercury enters the bloodstream, it may affect the brain and the kidneys. With a high enough concentration of mercury, you may suffer chronic kidney damage. Large amounts of mercury in the bloodstream can also result in massive blood loss and fluid loss from kidney failure. Often one of the characteristic diagnostic markers of acute exposure is excess protein in the urine.

6. Respiratory issues

While mercury can potentially cause health issues if ingested orally, the more prominent danger comes from inhaling its vapors as it evaporates. This allows the mercury vapor to reach the lungs, potentially contributing to severe respiratory problems. Pneumonitis, or inflammation of the lung tissue, happens almost immediately, while continued exposure to mercury vapors can lead to bronchitis and pneumonia. This can eventually progress to pulmonary edema, which is characterized by an excess amount of fluid in the lungs and potentially respiratory failure.

7. Developmental issues

Exposure to mercury can be the most damaging to developing children, infants, and fetuses. Along with many of the above symptoms, mercury can cause long-term developmental issues. Infants and children exposed to high concentrations may experience problems or delays with:

  • General cognitive abilities
  • Coordination and fine motor skills
  • Visual-spatial awareness
  • Language development

Diagnosing and treating mercury poisoning

Experiencing symptoms is often the first step to understanding that one is suffering from mercury poisoning. It’s frequently what brings a person into a healthcare provider’s office in the first place. From there, the healthcare provider may perform a variety of tests to determine if one does have mercury poisoning and to what extent: whether it can be categorized as mild, acute, or chronic exposure. Diagnosis usually involves a physical examination, blood tests, and urine tests. A healthcare provider might also ask about diet and lifestyle.

Treating mercury toxicity usually revolves around ceasing any exposure to mercury. This could mean changing one’s diet to remove mercury-rich fish and shellfish, or spending time away from a job site where there’s a high risk of mercury exposure. Ceasing exposure can sometimes be enough to help with mild symptoms. For more advanced forms of mercury poisoning, a healthcare provider may prescribe chelation therapy. This involves the use of chemicals known as chelating agents, which bind to mercury and other heavy metals, making them easier to eliminate and flush out of the body.

Heavy metal poisoning symptoms

Cadmium poisoning: causes and symptoms


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