Zocor (simvastatin) is a prescription drug used to help treat high cholesterol. Zocor can cause side effects that range from mild to serious. Examples include headache and nausea.

Zocor may be prescribed by itself or in combination with other drugs. It’s used in adults and certain children to treat:

Zocor may also be used to reduce the risk of death, stroke, and certain heart procedures in adults with heart disease or diabetes.

Zocor comes as a tablet that you swallow. It contains the active ingredient simvastatin. (An active ingredient is what makes a drug work.)

Keep reading to learn about the common, mild, and serious side effects that Zocor can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during their Zocor treatment. Examples of this drug’s commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Zocor. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Zocor unless your doctor recommends it.

Zocor may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.

Serious side effects have been reported with Zocor. These include:

If you develop serious side effects while taking Zocor, 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.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Zocor, but this side effect wasn’t reported in studies.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Zocor, visit MedWatch.

Get answers to some frequently asked questions about Zocor’s side effects.

How do side effects of Zocor compare with those of atorvastatin (Lipitor)?

Both Zocor and atorvastatin belong to the same group of drugs, called statins, so their mild side effects are very similar.

Atorvastatin has the same serious side effects as Zocor, but people taking higher atorvastatin doses may have an increased risk of a certain type of stroke.

Talk with your doctor about your health history so they can determine which treatment is the best option for you.

Does Zocor cause sexual side effects?

It’s possible. Sexual side effects were not reported in studies of Zocor. But erectile dysfunction was reported as a side effect after the drug became available on the market. Erectile dysfunction is the inability to get or maintain an erection long enough to have sex.

If you experience sexual side effects while taking this drug, talk with your doctor about possible causes and treatments.

Can Zocor cause long-term side effects?

It’s possible but rare. Long-term side effects are side effects that may start during your treatment and continue even after you stop taking the drug. They may also start after you’ve taken the drug for a while.

Zocor may cause serious side effects, such as myopathy (muscle pain or weakness) and rhabdomyolysis* (a breakdown of your muscle). In most cases, these side effects go away after you stop taking Zocor. In rare cases, they can lead to kidney problems, including kidney failure and death.

Zocor can also cause liver damage in some people and, in rare cases, this can lead to liver failure.

If you have more questions about long-term side effects from Zocor, talk with your doctor.

* For more details on these side effects, see the “Side effects explained” section below.

Will Zocor 10 mg cause different side effects than other strengths of the drug?

It’s possible. Side effects based on different drug strengths were not reported in Zocor’s studies. But it’s common for higher drug strengths to cause an increased risk of side effects. For example, taking doses of 80 milligrams (mg) daily can increase your risk of myopathy and rhabdomyolysis*.

Talk with your doctor if you have concerns about your Zocor dosage and potential side effects.

* For more details on these side effects, see the “Side effects explained” section below.

Does Zocor cause certain side effects in older adults?

Yes. In Zocor’s studies, older adults (ages 65 years and older) taking a daily dose of 80 mg had a higher risk of myopathy and rhabdomyolysis than younger people.

Due to this risk, your doctor will likely monitor you closely for signs of myopathy or rhabdomyolysis if you’re age 65 years or older. They’ll do this by ordering blood tests regularly during your Zocor treatment.

Learn more about some of the side effects Zocor may cause.

Myopathy and rhabdomyolysis

In rare cases, Zocor can cause a breakdown of your muscle tissue. This is known as myopathy, or rhabdomyolysis if it’s severe. The breakdown of this tissue causes protein in your muscles (known as myoglobin) to be released into your blood and in your body. Having too much myoglobin can cause kidney damage and, in rare cases, even death.

In Zocor studies, myopathy and rhabdomyolysis occurred more frequently during the first year of treatment. Other factors that may increase your risk of these side effects include:

  • taking higher doses of Zocor
  • taking other drugs along with Zocor that may cause Zocor to accumulate in your body
  • having kidney problems
  • being age 65 years or older
  • having untreated hypothyroidism (underactive thyroid)
  • being of Chinese ancestry

What might help

You should talk with your doctor about symptoms to watch for. For rhabdomyolysis, these often include muscle weakness, fever, fatigue (low energy), extreme soreness, and dark, tea-colored urine. To help prevent rhabdomyolysis, make sure you stay hydrated, especially before exercising.

Also, it’s important to talk with your doctor about your health history and all the medications you take before starting treatment. Sharing this information can help them determine whether you have an increased risk of myopathy or rhabdomyolysis. If you do, they may recommend a different treatment option for you.

If your doctor prescribes Zocor for you, they’ll likely order blood tests regularly to check for signs of myopathy or rhabdomyolysis.

Urinary tract infections

Urinary tract infections (UTIs) were commonly reported by people who took Zocor. A UTI is an infection in your bladder, kidney, or urinary tract. Left untreated, UTIs can become serious, and the infection can spread.

In rare cases, UTI can cause sepsis, which can be fatal. Sepsis was not reported in studies of Zocor.

Symptoms of a UTI can include:

What might help

To help prevent UTIs, you should stay hydrated and not hold your urine for long periods of time. If you suspect you have a UTI, talk with your doctor. They can test your urine to determine whether you do. If they confirm that you have a UTI, they’ll likely give you an antibiotic to treat the infection.

Upper respiratory infections

Upper respiratory infections, such as bronchitis, were commonly reported in studies of Zocor. Bronchitis occurs when your bronchial tubes (air passages between your throat and lungs) become inflamed and cause mucus to build up.

Symptoms of bronchitis can include:

What might help

To help prevent bronchitis, you should try to avoid inhaling irritants, such as smoke, and ensure you are getting plenty of rest.

Talk with your doctor if you have symptoms of bronchitis. In most cases, this condition can be treated at home with over-the-counter (OTC) medications.

Your doctor may recommend OTC ibuprofen (Advil, Motrin) or acetaminophen (Tylenol) to help relieve fever. Other OTC drugs, such as guaifenesin/dextromethorphan (Mucinex DM) or dextromethorphan (Delsym), may also help loosen mucus and manage a cough.

If your symptoms don’t ease with OTC medications or become severe, let your doctor know. They may recommend a chest X-ray or a blood test to determine whether you have pneumonia or a different infection.

If your doctor confirms you have an infection other than bronchitis, they’ll likely prescribe an antibiotic to treat it.

Constipation

Constipation was a commonly reported side effect in studies of Zocor. This means you have hard, dry stools or are having fewer than three bowel movements per week.

What might help

To help prevent constipation, you should stay hydrated and eat high fiber foods, including fruits, vegetables, and whole grains. If you’re not passing stool as often as you did before starting Zocor, talk with your doctor. They can suggest a stool softener or other options to help relieve your constipation.

Eczema

Eczema was a commonly reported side effect in Zocor’s studies. Eczema can cause itchy, irritated skin that’s usually dry and discolored.

What might help

Staying hydrated and keeping your skin moisturized can help prevent eczema. If you notice a change in your skin while taking Zocor, talk with your doctor. They may be able to suggest medications, such as an antihistamine, which can help treat your eczema.

Allergic reaction

Like most drugs, Zocor can cause an allergic reaction in some people, but this side effect wasn’t reported in studies. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

If your doctor confirms you’ve had a mild allergic reaction to Zocor, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Zocor, they may have you switch to a different treatment.

Keeping track of side effects

During your Zocor treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Taking notes and sharing them with your doctor will help them learn more about how Zocor affects you. They can then use this information to adjust your treatment plan if needed.

Zocor may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether Zocor is a good treatment option for you. Talk with your doctor about your health history before starting this medication. Factors to consider include those described below.

Increased risk of myopathy. Certain factors can cause an increased risk of myopathy, which can lead to serious complications, such as rhabdomyolysis. These factors include: being age 65 years or older, having kidney issues (such as kidney failure), and having untreated hypothyroidism. They also include taking higher doses of Zocor or taking it along with certain other medications. People with Chinese ancestry may have a higher risk of myopathy as well. Your doctor will help you decide whether Zocor is safe for you, depending on your individual circumstances.

History of diabetes. Zocor can cause increases in your fasting blood sugar level and HbA1c test results. If you have a history of diabetes, your doctor will give you guidance on how to take Zocor safely.

Liver problems. Taking Zocor may cause liver problems, including liver failure. If you already have liver issues, Zocor may worsen them. Let your doctor know if you have liver problems before you start Zocor treatment. They’ll determine whether this medication is safe for you to take.

Kidney problems. If you have kidney problems, taking Zocor can increase your risk of serious side effects, such as myopathy and rhabdomyolysis. Tell your doctor if you have kidney problems before starting Zocor. They may prescribe this drug for you at a dose that is lower than usual.

Allergic reaction. If you’ve had an allergic reaction to Zocor or any of its ingredients, your doctor will likely not prescribe it for you. Ask them about other medications that might be better options.

Alcohol and Zocor

There are no known interactions between alcohol and Zocor. But both Zocor and consuming large amounts of alcohol can cause liver damage. And drinking large amounts of alcohol during your Zocor treatment can increase your risk of liver damage.

Talk with your doctor about how much alcohol, if any, is safe for you to drink with this medication.

Pregnancy and breastfeeding while taking Zocor

Zocor is not safe to take while pregnant. This drug interrupts cholesterol creation and can cause harm to a fetus.

It’s not known whether Zocor treatment is safe while breastfeeding. But because it has the potential to interrupt cholesterol creation in infants who are breastfed, your doctor will likely recommend that you do not take it while breastfeeding.

Side effects can occur with Zocor but are usually mild. If you have questions about side effects this drug can cause, talk with your doctor. Examples of questions to help get you started include:

  • Does my risk of rhabdomyolysis depend on the dose of Zocor I take?
  • Do I have a higher risk of side effects than other people?
  • How do the side effects of Zocor compare with other statins used to treat high cholesterol?

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Disclaimer: Healthline 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.