Manganese is a trace mineral, meaning very small amounts of it are needed to maintain a healthy body. Several biological processes require manganese including blood clotting, sex hormone production and connective tissue and bone formation. If manganese is taken in very small doses, it is generally safe, although some mild side effects may result. However, doses of manganese greater than 11 milligrams per day can cause very serious side effects. Because of this danger, manganese supplements should only be taken under the close supervision of a doctor.
Neurological Side Effects
Large doses of manganese can cause serious neurological side effects, which often resemble the symptoms of Parkinson's disease. Muscle tremor is one of the key side effects of manganese toxicity. Additional possible side effects include rigidity or stiffness of muscles, loss of balance or coordination, and difficultly starting or completing movements, a condition known as bradykinesia. Less likely side effects include fatigue, stooped posture, speech problems, difficulty swallowing and sexual dysfunction. The Linus Pauling Institute reports that children who are exposed to high levels of manganese experience negative effects on brain function and behavior.
In rare cases, a person may experience a severe allergic reaction to manganese. The symptoms of an allergic reaction include itching, rash, or hives. Severe reactions can cause swelling of the face, lips, tongue and throat, which can lead to difficulty breathing, wheezing and coughing. If you or someone you know experiences these symptoms, call emergency health services immediately.
Interactions With Medications
If you are taking any medications, there is a chance that manganese could interact with them. Speak to your doctor before taking manganese, especially if you are taking antacids, laxatives, antibiotics or the blood pressure lowering medication reserpine. The University of Maryland Medical Center reports that these drugs may hinder the absorption of manganese. Antipsychotic drugs may intensify and other manganese side effects you experience.
People with chronic liver conditions, such as cirrhosis, remove manganese from the blood much more slowly than people with healthy livers. As a result, people with liver problems may experience side effects after taking doses of manganese smaller than 11 grams per day. People with anemia caused by iron deficiency absorb more manganese from food than healthy people, meaning they may also experience side effects from smaller doses of manganese.