Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Zocor (Simvastatin). If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking Zocor (Simvastatin). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• Constipation
• Diarrhea
• difficulty getting/maintaining an erection (men)
• gas
• headache
• nausea
• nightmares
• skin rash
• trouble sleeping
• upset stomach

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• breathing problems (e.g., shortness of breath, persistent cough)
• confusion
• memory loss
• signs of Depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• symptoms of liver damage (e.g., yellow skin or eyes, abdominal pain, dark urine, clay-coloured stools, loss of appetite, nausea and vomiting, or itching)
• symptoms of muscle damage (e.g., unexplained muscle pain, tenderness, or weakness, or brown or discoloured urine – especially if you also have a Fever or a general feeling of being unwell)

Stop taking the medication and seek medical attention immediately if any of the following occur:

• severe skin rash, including skin blistering and peeling (possibly with headache, fever, coughing, or aching before the rash begins)
• symptoms of a serious allergic reaction (e.g., swelling of the face or throat, Hives, or difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Zocor (Simvastatin).

10 mg
Each peach-coloured, oval, biconvex, film-coated tablet, engraved "MSD 735" on one side and plain on the other, contains 10 mg of Zocor (Simvastatin). Nonmedicinal ingredients: ascorbic acid, butylated hydroxyanisole, citric acid monohydrate, hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, pregelatinized starch, red ferric oxide, talc, titanium dioxide, and yellow ferric oxide.

20 mg
Each tan, oval, biconvex, film-coated tablet, engraved "MSD 740" on one side and plain on the other, contains 20 mg of Zocor (Simvastatin). Nonmedicinal ingredients: ascorbic acid, butylated hydroxyanisole, citric acid monohydrate, hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, pregelatinized starch, red ferric oxide, talc, titanium dioxide, and yellow ferric oxide.

40 mg
Each brick-red, oval, biconvex, film-coated tablet, engraved "MSD 749" on one side and plain on the other, contains 40 mg of Zocor (Simvastatin). Nonmedicinal ingredients: ascorbic acid, butylated hydroxyanisole, citric acid monohydrate, hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, pregelatinized starch, red ferric oxide, talc, and titanium dioxide.

Do not take Zocor (Simvastatin) if you:

• are allergic to Zocor (Simvastatin) or any ingredients of the medication
• are breast-feeding
• are pregnant or plan to become pregnant
• have active liver disease or unexplained increases in liver function tests
• are taking certain other medications, such as:
• "azole" antifungal medications (e.g., fluconazole, ketoconazole)
• protease inhibitors (e.g., boceprevir, ritonavir, telaprevir)
• macrolide antibiotics (e.g., erythromycin, clarithromycin)
• medications containing Cobicistat
• nefazodone
• Gemfibrozil
• Cyclosporine
• Danazol

There may be an interaction between Zocor (Simvastatin) and any of the following:

• Amiodarone
• Amlodipine
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• Aprepitant
• asunaprevir
• "azole" antifungals (e.g., itraconazole, ketoconazole, Voriconazole)
• Bicalutamide
• Bezafibrate 
• Bosentan
• calcium channel blockers (e.g., amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carbamazepine
• cobicistat
• Colchicine
• conivaptan
• Crizotinib
• cyclosporine
• Cyproterone 
• dabigatran
• Dabrafenib
• daclatasvir
• danazol
• Dasatinib
• Deferasirox
• Dronedarone
• elbasvir
• Eltrombopag
• Enzalutamide
• fenofibrate
• gemfibrozil
• grapefruit juice
• grazoprevir
• Haloperidol
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• Lomitapide
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• mifepristone 
• Mitotane
• Metronidazole
• Modafinil
• nefazodone
• niacin (nicotinic acid)
• niacinamide
• Phenobarbital
• Phenytoin
• primidone
• proton pump inhibitors (e.g., Lansoprazole, Omeprazole)
• quinine
• red yeast rice
• rifabutin
• rifampin
• Risperidone
• St. John's wort
• Sertraline
• Sildenafil
• siltuximab
• simeprevir
• Sitagliptin
• Teriflunomide
• Ticagrelor
• Tocilizumab 
• trabectedin
• tyrosine kinase inhibitors (e.g., dasatinib, imatinib, Nilotinib, Sunitinib)
• Warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Zocor (Simvastatin). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Zocor (Simvastatin).

Alcohol: Consumption of alcohol can increase the risk of liver damage when taking Zocor (Simvastatin). If you  regularly drink more than 3 drinks of alcohol daily, the risk is further increased and you should be closely monitored by your doctor while taking Zocor (Simvastatin).

Diabetes: Zocor (Simvastatin), like other medications in this family, may cause a loss of control of blood sugar levels and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Zocor (Simvastatin), and whether any special monitoring is needed.

Grapefruit juice: Don't drink grapefruit juice while taking Zocor (Simvastatin), as it can increase the amount of Zocor (Simvastatin) in the blood and increase the risk of serious side effects.

Kidney problems: People with decreased kidney function should discuss with their doctor how Zocor (Simvastatin) may affect their medical condition, how their medical condition may affect the dosing and effectiveness of Zocor (Simvastatin), and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause Zocor (Simvastatin) to build up in the body, causing side effects. If you have a history of liver disease, discuss with your doctor how Zocor (Simvastatin) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Zocor (Simvastatin), and whether any special monitoring is needed.

Laboratory tests show signs of harmful effects to the liver that may occur for a small percentage of people who take Zocor (Simvastatin). When Zocor (Simvastatin) is stopped, liver function usually slowly returns to normal. Your doctor will perform regular tests to check your liver function.

Zocor (Simvastatin) should not be used by people with active liver disease or by people whose liver function tests are higher than normal.

Muscle effects: In rare cases, serious muscle pain, cramps, and weakness have been associated with the use of statin medications (i.e., cholesterol-lowering medications whose names end in "statin," such as Atorvastatin, Fluvastatin, Lovastatin, Pravastatin, Rosuvastatin, or Zocor (Simvastatin)), especially at higher doses. Before taking this medication, tell your doctor or pharmacist if you:

• are 65 years of age or older
• are female
• are taking other cholesterol-lowering medications such as fibrates (e.g., gemfibrozil, Fenofibrate) or Niacin
• do excessive physical exercise
• have a family history of muscular disorders
• have diabetes
• have had any past problems with the muscles (pain, tenderness) after taking a statin medication
• have Hypothyroidism (low Thyroid) that is not controlled with medication
• have kidney or liver problems
• have undergone surgery or other tissue injury
• regularly drink 3 or more alcoholic drinks daily

Report any unexplained muscle pain, tenderness, weakness, or cramps, or any brown or discoloured urine to your doctor immediately, particularly if you are also experiencing malaise (a general feeling of being unwell) or fever.

Pregnancy: Zocor (Simvastatin) should not be taken during pregnancy. It may cause harm to the unborn baby. If you become pregnant, stop taking Zocor (Simvastatin) and contact your doctor immediately.

Breast-feeding: It is not known if Zocor (Simvastatin) passes into breast milk. If you are a breast-feeding mother and are taking Zocor (Simvastatin), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Zocor (Simvastatin) have not been established for children less than 10 years of age or in girls who have not started menstruating.

Seniors: If you are 65 years of age or older, you may experience more side effects. Your doctor will monitor you closely while you are taking Zocor (Simvastatin).