Key takeaways

  • Sinemet (carbidopa/levodopa) is prescribed for Parkinson’s disease and certain types of parkinsonism. The most common side effects include involuntary movements and nausea.
  • Mild side effects may include vomiting, hair loss, abdominal pain, headache, dry mouth, dizziness, difficulty sleeping, anxiety, and increased sweating. Serious side effects can include falling asleep during daily activities, high fever and confusion, hallucinations, melanoma, and compulsive behaviors.
  • If you develop serious side effects like unusual thoughts or behaviors, talk with your healthcare professional right away. Call 911 or your local emergency number if side effects seem life threatening.

Sinemet (carbidopa/levodopa) is a brand-name oral tablet prescribed for Parkinson’s disease and certain types of parkinsonism in adults. Like any medication, Sinemet can cause side effects, such as involuntary movements and nausea.

Some side effects are more common than others. If you have any concerns about side effects, consider reaching out to a healthcare professional.

Sinemet can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are the more common side effects reported by people who took Sinemet in clinical trials:

Mild side effects can occur with Sinemet use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to the drug’s prescribing information.

Mild side effects that have been reported with Sinemet include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Sinemet and want to tell the FDA about it, visit MedWatch.

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Sinemet may cause serious side effects. Some may be more common, while others are rare. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Sinemet’s prescribing information.

If you develop serious side effects while taking Sinemet, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • involuntary movements
  • falling asleep during daily activities
  • high fever and confusion
  • unusual thoughts or behaviors, such as:
  • melanoma, which may include symptoms such as:
    • a new mole or a change in the color, shape, or size of an existing mole
    • a painful, itchy, or tender sore
    • a sore that won’t heal
  • compulsive behavior (behaviors or actions that are difficult to resist), such as:
    • intense urges to gamble or spend money
    • increased sexual urges
    • binge eating
  • depression (see “Side effect specifics” for details)
Allergic reaction

For some people, Sinemet can cause an allergic reaction. It’s not clear whether this side effect occurred in the drug’s studies. In general, symptoms of allergic reaction can be mild or serious.

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away.

Learn more about some of the side effects that Sinemet may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Sinemet.

High blood pressure

There have been rare reports of high blood pressure in people taking Sinemet. In many cases, high blood pressure doesn’t cause any noticeable symptoms. But rare and severe cases of high blood pressure may cause symptoms, including:

Your risk of high blood pressure from Sinemet may be higher if you take a tricyclic antidepressant (TCA) like amitriptyline (Elavil).

If you and your doctor decide to start Sinemet, they may monitor your blood pressure closely during treatment. They may also ask you to monitor your blood pressure at home.

If you experience symptoms of high blood pressure, tell your doctor. They can help determine the cause and ways to treat it. They can also help decide if it’s safe for you to continue taking Sinemet.

Depression

Some people have reported symptoms of depression while taking Sinemet. Depression is a mental health condition characterized by feelings of sadness or emptiness. Other symptoms may include:

In severe cases, depression may lead to suicidal thoughts or behaviors.

Before you start Sinemet, tell your doctor if you’ve had depression. They may consider another medication instead of Sinemet for your condition. If you and your doctor decide that you’ll start Sinemet, they’ll likely monitor you more closely for symptoms of depression.

If you develop symptoms, tell your doctor right away. They can help determine whether you should stop taking Sinemet. If you have thoughts of harming yourself, call 911 or your local emergency number.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Taking too much carbidopa/levodopa (Sinemet) can lead to harmful effects, such as arrhythmia (an irregular heart rhythm). In animal studies, very high doses of Sinemet led to death. However, animal studies don’t always indicate what will happen in humans.

For information about Sinemet’s recommended dosage, see this article.

If you accidentally take too much Sinemet or carbidopa/levodopa, call your doctor. You can also call the American Poison Help Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

It’s possible for Sinemet to cause long-term side effects. These can last for a while after you stop taking the drug.

Examples of long-term side effects reported in clinical trials of Sinemet include falling asleep during daily activities.

Talk with your doctor or pharmacist if you have more questions about Sinemet’s long-term side effects.

Typically, yes. In clinical trials, Sinemet caused similar side effects in older adults (ages 65 years and above) and other adults.

However, Sinemet may clear out of the body more slowly in older adults than in other adults. This means Sinemet may reach higher levels in older people than in younger people. Having a higher level of the drug in your body can increase the risk of side effects.

If you have concerns about taking Sinemet given your age, talk with your doctor.

Before taking Sinemet, discuss your health history with your doctor. Sinemet may not be right for you if you have certain medical conditions or other factors affecting your health. Some of these are known as contraindications. Be sure to talk with your doctor if any of the following apply to you:

Sinemet is a brand-name oral tablet prescribed for Parkinson’s disease and certain types of parkinsonism in adults. Like any medication, Sinemet can cause side effects. Some common examples include such as involuntary movements and nausea.

If you have any concerns about the side effects of Sinemet, reach out to a healthcare professional.

Disclaimer: While Medical News Today strives for factual, comprehensive, and current drug information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.