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

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.

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.

Ways to manage

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. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Sinemet, your doctor may recommend taking a different medication instead.

Sinemet may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

What side effects can occur if you take too much carbidopa/levodopa (Sinemet)?

Taking too much carbidopa/levodopa 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.

Sinemet is a brand-name drug that contains the active ingredients carbidopa and levodopa. The generic version is carbidopa/levodopa. A generic medication is an identical copy of the active ingredient in a brand-name medication.

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 Control 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.

Does Sinemet cause long-term side effects?

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.

Are the side effects of Sinemet in older people similar to those in other adults?

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.

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 while taking Sinemet. In many cases, high blood pressure doesn’t cause any noticeable symptoms. But rare and severe cases of high blood pressure can cause symptoms, including:

Your risk of high blood pressure from Sinemet may be higher if you take a tricyclic antidepressant (TCA). (TCAs are a type of medication prescribed to treat depression.)

What you can do

Before starting Sinemet, be sure to tell your doctor if you take a TCA. 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.

To learn more about Sinemet interactions with other medications, see this article.

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.

What you can do

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.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

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. (A contraindication is a factor or condition that could prevent your doctor from prescribing a drug due to risk of harm.) Be sure to talk with your doctor if any of the following apply to you:

To learn more about the conditions Sinemet is prescribed to treat, see this list of articles about Parkinson’s disease.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.