Amantadine is a drug that helps treat Parkinson's disease and other conditions. People can experience mild to severe side effects while taking this medication.

Amantadine comes in capsule, tablet, or liquid forms. The brand names for amantadine are Gocovri and Osmolex ER.

The most common side effects are nausea, dizziness, and sleeping problems. Some less common but more severe side effects include changes to the central nervous system and the heart, as well as suicidal thoughts or actions.

This article looks into the uses for amantadine and the side effects that a person might experience.

A person popping some Amantadine pills out of a blister pack. Share on Pinterest
A doctor may prescribe amantadine to help treat Parkinson's disease.

Amantadine can treat a few conditions, and doctors most often prescribe it to treat Parkinson's disease.

Amantadine can also help with movement-related side effects of antipsychotic medications. The medical name for these effects is extrapyramidal symptoms.

Extrapyramidal symptoms are similar to the movements that characterize Parkinson's disease. They may involve muscle spasms, jerkiness, tremors, and slowness.

Amantadine can also prevent and treat the influenza A virus by helping to stop the virus from replicating. It is not, however, a substitute for an annual flu vaccination.

The most common side effects of amantadine, affecting 5–10% of people who take the recommended dosage, include:

  • nausea
  • trouble sleeping
  • dizziness or lightheadedness

Less common side effects, affecting 1–5% of people, include:

Infrequent side effects, affecting 0.1 to 1% of people, include:

Amantadine can cause more severe, and sometimes dangerous, side effects, though this is uncommon. These effects can include:

Suicidal thoughts or actions

Suicidal thoughts or actions are a rare side effect of amantadine, occurring in fewer than 0.1% of people.

Many people affected in this way have taken amantadine for influenza prevention or treatment. This side effect can develop in people with no history of psychiatric illness.

People taking amantadine, and those close to them, should look carefully for any behavioral changes, including agitation, personality changes, paranoia, depression, and anxiety.

Suicide prevention

  • If you know someone at immediate risk of self-harm, suicide, or hurting another person:
  • Call 911 or the local emergency number.
  • Stay with the person until professional help arrives.
  • Remove any weapons, medications, or other potentially harmful objects.
  • Listen to the person without judgment.
  • If you or someone you know is having thoughts of suicide, a prevention hotline can help. The National Suicide Prevention Lifeline is available 24 hours a day at 1-800-273-8255.

Central nervous system effects

Some people who have taken amantadine have reported falling asleep while performing routine activities, such as driving. The risk is higher in people who take at least one other sedating medication and in people who experience sleep disorders.

Anyone with a history of epilepsy or another condition that causes seizures should monitor any change in seizure activity while taking amantadine.

Symptoms such as dizziness, low blood pressure, and feeling faint have occurred in people taking amantadine. Alcohol consumption could increase this risk.

Impulse control

People who take amantadine may experience impulsive thoughts and behaviors. Common impulsive behaviors include gambling, risky sexual activity, spending money, or binge eating.

The person may not realize that their behavior is unusual, so it is important for caregivers to monitor for these behaviors.

Congestive heart failure

In rare cases, a person may develop congestive heart failure while taking amantadine.

For anyone with a history of congestive heart failure or edema, it is important to monitor closely for any symptoms, such as increased swelling or shortness of breath.

Neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) is a rare but potentially fatal condition that doctors associate with fever or hyperthermia. A person with NMS may also exhibit symptoms such as decreased consciousness, changes in muscle movement, rapid breathing, or a rapid heart rate.

NMS may develop when people have reduced their dosage or stopped taking amantadine. It is important to talk to a doctor before stopping the treatment.

People should be aware of the following when taking amantadine:

Overdose

An overdose of amantadine can be fatal. It may result in toxicity of the heart, lungs, kidneys, or central nervous system.

Amantadine overdose has occurred in people with impaired kidney function who are not able to excrete the drug thoroughly.

Kidney or liver disease

The kidneys primarily excrete amantadine via the urine. In people with impaired kidney function, the drug can build up in the body. The doctor will lower the dose of amantadine, as a result.

Amantadine can also increase liver enzyme numbers. Anyone with a history of liver disease should take amantadine with caution.

Skin cancer

People with Parkinson's disease have a higher risk of melanoma, compared with the general population. It is unclear whether this risk relates to medications, the disease itself, or other factors.

People taking amantadine should monitor their skin for changes and see a doctor for skin exams regularly.

Pregnancy and breastfeeding

Amantadine is a pregnancy category C drug, which means that researchers have not performed well-controlled studies in pregnant women.

As a result, doctors do not know the effects of amantadine on a developing fetus. They do not recommend taking the drug while breastfeeding.

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If a person takes amantadine at the same time as anticholinergic drugs, they may experience dizziness, dry mouth, or blurred vision.

Amantadine may interact with other drugs, including the following:

Anticholinergic drugs

These can worsen some side effects of amantadine, including dry mouth, dizziness, urinary retention, and blurred vision.

Stimulants

Central nervous system stimulants can cause increased anxiety, trouble sleeping, and irritability in people who also take amantadine. These stimulants include methylphenidate and amphetamines.

Flu vaccine

Because of possible interference, do not receive a nasal live attenuated influenza vaccine within 2 weeks of taking amantadine.

Heart drugs

The National Library of Medicine (NLM) report that increased plasma amantadine concentration developed in a man who took a blood pressure medication called triamterene (Dyazide).

They also report that quinidine (Quinaglute), a drug that can help treat heart arrhythmias, can reduce the kidneys' ability to clear amantadine from the body.

Alcohol

The NLM recommend that people avoid excessive alcohol use while taking amantadine. This is because it can increase side effects, including:

  • dizziness
  • lightheadedness
  • confusion
  • low blood pressure when standing up, called orthostatic hypotension

Anyone who drinks alcohol regularly should consult the doctor before taking amantadine.

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A person should seek advice from a doctor if they experience any side effects from taking amantadine.

Mild side effects may go away in a few days or weeks. If side effects are persistent or bothersome, speak with the doctor.

If side effects are severe, contact the doctor as soon as possible. Anyone who believes that their side effects may be life-threatening should call 911 or otherwise seek emergency medical assistance.

Other drugs can provide the same type of treatment as amantadine. Speak with a doctor about possible alternatives.

Amantadine is a drug that people mainly use to treat Parkinson's disease. Minor side effects are common, and some include nausea, insomnia, and dizziness.

Severe and potentially dangerous side effects are less common. Some of these include NMS, suicidal thoughts or behaviors, psychosis, and heart problems.

It is also important to be aware that amantadine can interact with other drugs.

Anyone with concerns about the side effects of amantadine should speak with their doctor.