Simvastatin: Uses, Dosage & Side Effects
A cholesterol-lowering statin medication used to reduce cardiovascular risk
Simvastatin is a widely prescribed statin medication that lowers cholesterol levels in the blood and reduces the risk of heart attack, stroke, and other cardiovascular events. It works by blocking an enzyme (HMG-CoA reductase) involved in cholesterol production in the liver. This comprehensive guide covers dosage, side effects, drug interactions, contraindications, and storage based on international medical guidelines.
Quick Facts
Key Takeaways
- Simvastatin lowers LDL (“bad”) cholesterol and triglycerides while raising HDL (“good”) cholesterol, reducing the risk of cardiovascular disease.
- Take simvastatin in the evening, as cholesterol synthesis is highest at night; it can be taken with or without food.
- Serious drug interactions exist with certain antifungals, macrolide antibiotics, HIV protease inhibitors, and grapefruit juice – always tell your doctor about all medications you take.
- Report unexplained muscle pain, tenderness, or weakness immediately, as these may indicate a rare but serious condition called rhabdomyolysis.
- Simvastatin is contraindicated during pregnancy and breastfeeding; women of childbearing age should use effective contraception.
What Is Simvastatin and What Is It Used For?
Simvastatin belongs to a class of medications known as statins (HMG-CoA reductase inhibitors). It works by inhibiting an enzyme called HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver. By reducing the liver’s cholesterol output, simvastatin triggers an increase in LDL receptors on liver cells, which in turn pull more LDL cholesterol out of the bloodstream. The net result is a significant reduction in total cholesterol, LDL cholesterol, and triglycerides, along with a modest increase in HDL (“good”) cholesterol.
Cholesterol is a waxy, fat-like substance that your body needs for building cells and producing hormones. However, too much cholesterol – particularly LDL cholesterol – can accumulate in the walls of your arteries, forming fatty deposits called atherosclerotic plaques. Over time, these plaques narrow the arteries and restrict blood flow to vital organs like the heart and brain. If a plaque ruptures, it can trigger a blood clot that blocks the artery entirely, potentially causing a heart attack (myocardial infarction) or stroke.
The landmark Scandinavian Simvastatin Survival Study (4S), published in The Lancet in 1994, was one of the first large-scale randomised controlled trials to demonstrate that statin therapy significantly reduces cardiovascular mortality. The study showed that simvastatin reduced overall mortality by 30% and major coronary events by 34% in patients with coronary heart disease. Since then, simvastatin has become one of the most widely prescribed medications worldwide and is included on the WHO Model List of Essential Medicines.
Approved Indications
Simvastatin is prescribed for the following conditions:
- Primary hypercholesterolaemia (high LDL cholesterol) – when dietary changes alone have not been sufficient to lower cholesterol to target levels.
- Mixed dyslipidaemia (combined hyperlipidaemia) – elevated LDL cholesterol together with high triglycerides and/or low HDL cholesterol.
- Homozygous familial hypercholesterolaemia (HoFH) – a rare inherited condition causing extremely high cholesterol levels. Simvastatin may be used in combination with other lipid-lowering therapies.
- Cardiovascular risk reduction – in patients with established coronary heart disease, diabetes mellitus, history of stroke, or peripheral vascular disease. Simvastatin reduces the risk of heart attack, stroke, and cardiovascular death regardless of baseline cholesterol levels.
For most patients, high cholesterol causes no noticeable symptoms. The only reliable way to know your cholesterol levels is through a blood test (lipid panel). Your doctor will use your cholesterol results, along with other cardiovascular risk factors, to determine whether statin therapy is appropriate. You should continue to follow a cholesterol-lowering diet and exercise regularly while taking simvastatin, as these lifestyle measures complement the medication’s effects.
What Should You Know Before Taking Simvastatin?
Contraindications
Simvastatin must not be used in the following situations:
- Allergy to simvastatin or any of the inactive ingredients in the tablet.
- Active liver disease or unexplained persistent elevations in liver enzymes (transaminases).
- Pregnancy – simvastatin may cause harm to the unborn baby. Cholesterol and its biosynthetic products are essential for foetal development, and inhibiting their synthesis may be harmful.
- Breastfeeding – it is unknown whether simvastatin passes into breast milk; use is not recommended.
- Concurrent use of potent CYP3A4 inhibitors – the following medications must not be taken together with simvastatin due to the risk of severe muscle damage (rhabdomyolysis):
- Azole antifungals: itraconazole, ketoconazole, posaconazole, voriconazole
- Macrolide antibiotics: erythromycin, clarithromycin, telithromycin
- HIV protease inhibitors: indinavir, nelfinavir, ritonavir, saquinavir
- Hepatitis C antivirals: boceprevir, telaprevir
- Other: nefazodone, cobicistat, gemfibrozil, ciclosporin, danazol
If you are currently taking any of the medications listed above, do not start simvastatin without consulting your doctor. The combination can cause a dangerous condition called rhabdomyolysis, where muscle tissue breaks down and releases proteins into the bloodstream that can lead to kidney failure.
Warnings and Precautions
Before starting simvastatin, inform your doctor if any of the following apply to you:
- You consume alcohol regularly or in large amounts.
- You have a history of liver disease – simvastatin may not be appropriate, and liver function tests should be performed before starting treatment and periodically thereafter.
- You have kidney problems.
- You have thyroid disorders (hypothyroidism).
- You are 65 years of age or older – increased risk of muscle side effects.
- You are of East Asian descent – lower doses may be more appropriate due to differences in drug metabolism.
- You have a personal or family history of muscle disorders or have previously experienced muscle problems on a statin or fibrate.
- You are scheduled for surgery – your doctor may advise temporarily stopping simvastatin.
- You have severe respiratory problems.
- You have or have had myasthenia gravis or ocular myasthenia – statins may occasionally worsen these conditions or trigger new onset.
Your doctor should order a blood test to check your liver function before you start taking simvastatin. If you develop symptoms of liver problems during treatment – such as unusual fatigue, loss of appetite, upper abdominal pain, dark-coloured urine, or yellowing of the skin or eyes – contact your doctor immediately.
During treatment, your doctor will monitor you for signs of diabetes, particularly if you have risk factors such as high blood sugar, high triglycerides, overweight, or high blood pressure. Statins as a class have been associated with a small increase in the risk of developing type 2 diabetes, although the cardiovascular benefits generally outweigh this risk.
Seek medical attention right away if you experience unexplained muscle pain, tenderness, or weakness, especially if accompanied by fever or malaise. In rare cases, muscle problems can become serious (rhabdomyolysis), leading to kidney damage and, in very rare instances, death. The risk is higher at the 80 mg dose and when simvastatin is combined with certain other medications.
Pregnancy and Breastfeeding
Pregnancy: Simvastatin is contraindicated during pregnancy. Cholesterol and other products of cholesterol biosynthesis are essential for foetal development. If you become pregnant while taking simvastatin, stop the medication immediately and contact your doctor. Women of childbearing potential should use reliable contraception during treatment.
Breastfeeding: Simvastatin should not be taken while breastfeeding. It is not known whether simvastatin or its metabolites are excreted in human breast milk. Due to the potential for serious adverse effects in the nursing infant, breastfeeding should be discontinued during treatment.
Driving and Operating Machinery
Simvastatin is not expected to affect your ability to drive or operate machinery. However, some people may experience dizziness as a side effect. If you are affected, do not drive or use machines until you know how simvastatin affects you.
Grapefruit Juice
Grapefruit juice contains substances that inhibit the CYP3A4 enzyme, which is responsible for metabolising simvastatin. Drinking grapefruit juice while taking simvastatin can significantly increase the drug’s concentration in your blood, raising the risk of side effects, particularly muscle damage. Avoid grapefruit juice while on simvastatin therapy.
How Does Simvastatin Interact with Other Drugs?
Simvastatin is a prodrug that is converted to its active form in the liver. It is primarily metabolised by the cytochrome P450 enzyme CYP3A4. Drugs that inhibit CYP3A4 can slow the breakdown of simvastatin, leading to significantly elevated plasma levels and an increased risk of muscle toxicity (myopathy and rhabdomyolysis). This makes simvastatin’s interaction profile more complex than some other statins.
The table below summarises the most important drug interactions with simvastatin. This is not an exhaustive list – always inform your prescriber about every medication, supplement, and herbal product you use.
Major Interactions (Contraindicated or Simvastatin Must Be Stopped)
| Drug / Class | Used For | Risk |
|---|---|---|
| Itraconazole, ketoconazole, posaconazole, voriconazole | Fungal infections | Severe rhabdomyolysis risk; completely contraindicated |
| Erythromycin, clarithromycin, telithromycin | Bacterial infections | Severe rhabdomyolysis risk; contraindicated |
| HIV protease inhibitors (indinavir, nelfinavir, ritonavir, saquinavir) | HIV infection | Severe rhabdomyolysis risk; contraindicated |
| Boceprevir, telaprevir | Hepatitis C | Severe rhabdomyolysis risk; contraindicated |
| Gemfibrozil | Cholesterol/triglycerides | High rhabdomyolysis risk; contraindicated |
| Ciclosporin | Organ transplant / autoimmune | Severe rhabdomyolysis risk; contraindicated |
| Nefazodone | Depression | Severe rhabdomyolysis risk; contraindicated |
| Cobicistat | HIV pharmacokinetic booster | Severe rhabdomyolysis risk; contraindicated |
| Danazol | Endometriosis | Severe rhabdomyolysis risk; contraindicated |
| Fusidic acid (systemic) | Bacterial infections | Simvastatin must be stopped temporarily; restart only after fusidic acid course is complete |
Dose-Limiting Interactions (Maximum Simvastatin Dose Restricted)
| Drug / Class | Used For | Max Simvastatin Dose |
|---|---|---|
| Amiodarone | Irregular heartbeat | 20 mg/day |
| Verapamil, diltiazem | High blood pressure / angina | 20 mg/day |
| Amlodipine | High blood pressure / angina | 20 mg/day |
| Elbasvir/grazoprevir | Hepatitis C | 20 mg/day |
| Lomitapid | Homozygous familial hypercholesterolaemia | 40 mg/day |
Other Important Interactions
The following drugs also require caution when used with simvastatin:
- Warfarin and other anticoagulants (acenocoumarol, phenprocoumon) – simvastatin may enhance the anticoagulant effect. More frequent INR monitoring is recommended when starting or adjusting simvastatin dose.
- Fenofibrate and other fibrates – increased risk of myopathy. Use with caution; gemfibrozil is contraindicated (see above).
- Niacin (nicotinic acid) at lipid-modifying doses (≥1 g/day) – increased risk of myopathy.
- Colchicine – cases of myopathy have been reported when combined with simvastatin.
- Ticagrelor – antiplatelet drug; may increase simvastatin exposure.
- Daptomycin – antibiotic that can independently cause myopathy. Your doctor may temporarily stop simvastatin during daptomycin treatment.
- Rifampicin – a potent CYP3A4 inducer that may reduce simvastatin efficacy. However, the interaction is complex and clinical monitoring is advised.
- Bile acid sequestrants (e.g. cholestyramine, colestipol) – take simvastatin at least 2 hours before or 4 hours after bile acid sequestrants to avoid reduced absorption.
Always tell your doctor about all medications you are taking, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements. If a new medicine is prescribed for you, inform the prescriber that you are taking simvastatin.
What Is the Correct Dosage of Simvastatin?
Your doctor will decide the appropriate dose of simvastatin based on your individual risk profile, cholesterol levels, treatment goals, and any other medications you are taking. Simvastatin should always be taken in the evening, as the body produces more cholesterol at night. The tablet can be taken with or without food and should be swallowed whole with a glass of water.
Adults
Standard Adult Dosage
Starting dose: 10 mg, 20 mg, or in some cases 40 mg once daily in the evening.
Dose adjustment: Your doctor may adjust the dose after at least 4 weeks, based on your response.
Maximum dose: 80 mg once daily. However, the 80 mg dose carries a higher risk of muscle problems and is recommended only for patients with very high cholesterol and high cardiovascular risk who have not reached their treatment goals on lower doses, or who have been stable on the 80 mg dose for at least 12 months without muscle symptoms.
According to the ESC/EAS 2019 Guidelines for the Management of Dyslipidaemias, the target LDL cholesterol level depends on the patient’s overall cardiovascular risk. For very high-risk patients, the target is LDL <1.4 mmol/L (55 mg/dL) with at least a 50% reduction from baseline. Your doctor will consider whether simvastatin alone can achieve these targets or whether combination therapy (e.g. with ezetimibe) is needed.
If you are taking any of the interacting medications listed in the dose-limiting interaction table above (such as amiodarone, verapamil, diltiazem, or amlodipine), the maximum permitted dose of simvastatin is 20 mg per day. Your doctor may also prescribe lower doses if you have kidney problems or are of East Asian descent.
Children and Adolescents (10–17 years)
Paediatric Dosage
Starting dose: Usually 10 mg once daily in the evening.
Maximum dose: 40 mg once daily.
Simvastatin has been studied in boys aged 10–17 years and in girls who have had their first menstrual period (at least one year). It has not been studied in children under 10 years of age.
Elderly Patients
No specific dose adjustment is required based on age alone. However, elderly patients (65 years and older) may be more susceptible to muscle-related side effects. Your doctor may start with a lower dose and monitor you more closely.
Missed Dose
If you forget to take a dose, simply skip the missed dose and take your next dose at the usual time the following evening. Do not take a double dose to make up for a missed one. Setting a daily reminder or linking the dose to an evening routine (e.g. brushing your teeth) may help you remember.
Overdose
If you or someone else has taken too much simvastatin, contact a poison control centre or seek emergency medical attention immediately. There is no specific antidote for simvastatin overdose. Treatment is supportive, focusing on monitoring and managing symptoms. A few cases of overdose have been reported, with the maximum dose taken being 3.6 g, and all patients recovered without lasting effects.
Stopping Treatment
Do not stop taking simvastatin without consulting your doctor, even if you feel well. High cholesterol usually has no symptoms, and stopping the medication may cause your cholesterol levels to rise again, increasing your cardiovascular risk. If you experience side effects that concern you, talk to your doctor about adjusting the dose or switching to an alternative medication.
What Are the Side Effects of Simvastatin?
The following side effects have been reported with simvastatin. The frequency categories are based on clinical trial data and post-marketing surveillance reports from the EMA and FDA.
Rare Side Effects
- Low red blood cell count (anaemia)
- Numbness or weakness in the arms and legs
- Headache, tingling, dizziness
- Blurred vision, impaired vision
- Abdominal pain, constipation, flatulence, indigestion, diarrhoea, nausea, vomiting
- Skin rash, itching, hair loss
- Weakness, fatigue
Very Rare Side Effects
- Rhabdomyolysis – severe muscle breakdown that can lead to kidney failure; symptoms include severe muscle pain, tenderness, weakness, and dark-coloured urine
- Severe allergic reactions (anaphylaxis)
- Liver inflammation (hepatitis) with jaundice, dark urine, pale stools, fatigue, loss of appetite
- Liver failure (fatal and non-fatal cases reported)
- Pancreatitis (severe abdominal pain)
- Drug-related lichenoid skin eruptions (rash in the mouth or on the skin)
- Insomnia
- Memory loss, confusion
Frequency Not Known
- Erectile dysfunction
- Depression
- Tendon problems, occasionally with tendon rupture
- Persistent muscle weakness (immune-mediated necrotising myopathy)
- Myasthenia gravis (general muscle weakness, including breathing muscles)
- Ocular myasthenia (eye muscle weakness)
- Gynecomastia (breast enlargement in men)
Side Effects Reported with Statins as a Class
The following side effects have been reported with various statins and may also occur with simvastatin:
- Sleep disturbances, including nightmares
- Sexual difficulties
- Respiratory symptoms, including persistent cough, shortness of breath, or fever
- New-onset type 2 diabetes – more likely in patients with pre-existing risk factors (high blood sugar, high triglycerides, obesity, high blood pressure). The cardiovascular benefits of statin therapy generally outweigh this risk.
Laboratory Abnormalities
Blood tests may show elevated levels of liver enzymes (transaminases) and creatine kinase (CK, a muscle enzyme). These elevations are usually transient and reversible. Your doctor will perform periodic blood tests to monitor your liver function and muscle enzymes, particularly when starting treatment or increasing the dose.
Contact your doctor or go to the nearest emergency department immediately if you experience any of the following:
- Unexplained muscle pain, tenderness, or weakness, especially with fever or malaise
- Dark-coloured (brown) urine
- Yellowing of the skin or eyes (jaundice)
- Severe abdominal pain
- Swelling of the face, tongue, or throat causing difficulty breathing
- Weakness in arms or legs that worsens after activity, double vision, or drooping eyelids
Reporting Side Effects
If you experience any side effects, talk to your doctor or pharmacist. You can also report side effects directly to your national pharmacovigilance authority (e.g. the FDA MedWatch programme in the United States, the MHRA Yellow Card Scheme in the United Kingdom, or the EMA EudraVigilance system in the European Union). By reporting side effects, you help provide more information on the safety of this medicine.
How Should You Store Simvastatin?
Proper storage of simvastatin ensures the medication remains effective and safe throughout its shelf life. Follow these guidelines:
- Temperature: Store at or below 25°C (77°F). Do not freeze.
- Moisture: Keep tablets in their original packaging (blister pack or bottle) to protect from moisture.
- Light: Avoid prolonged exposure to direct sunlight.
- Children: Store out of the sight and reach of children.
- Opened containers: For plastic bottle packaging, the shelf life after first opening is typically 6 months.
- Expiry date: Check the expiry date (EXP) on the carton and blister. The expiry date refers to the last day of the stated month. Do not use simvastatin after this date.
Do not dispose of simvastatin in household waste or by flushing down the toilet. Return unused or expired medication to your pharmacy for safe disposal, in accordance with local regulations, to help protect the environment.
What Does Simvastatin Contain?
Active ingredient: Simvastatin. Each film-coated tablet contains 10 mg, 20 mg, 40 mg, or 80 mg of simvastatin.
Inactive ingredients (excipients): The exact composition may vary slightly between manufacturers, but commonly includes:
- Lactose monohydrate
- Microcrystalline cellulose
- Pregelatinised maize starch
- Butylated hydroxyanisole (E320)
- Magnesium stearate
- Ascorbic acid
- Citric acid monohydrate
- Hypromellose (E464)
- Titanium dioxide
- Macrogol 3350
- Triacetin
- Iron oxide red (E172)
- Iron oxide yellow (E172) – in 10 mg, 20 mg, and 80 mg tablets
- Iron oxide black (E172) – in 80 mg tablets
Simvastatin tablets contain lactose monohydrate. If you have been told by your doctor that you have an intolerance to certain sugars, contact your doctor before taking this medicine.
Tablet Appearance
The appearance of simvastatin tablets varies by strength and manufacturer. A common formulation (e.g. Simvastatin Teva) has the following appearance:
- 10 mg: Light pink, oval, film-coated tablets with a score line on one side
- 20 mg: Golden-brown, oval, film-coated tablets with a score line on one side
- 40 mg: Pink, oval, film-coated tablets with a score line on one side
- 80 mg: Brick-red, oval, film-coated tablets with a score line on one side
The score line allows the tablet to be divided into two equal halves. Available pack sizes vary by country and manufacturer and may include 10, 14, 20, 28, 30, 50, 56, 60, 84, 90, 98, 100, or 120 tablets.
Frequently Asked Questions About Simvastatin
Simvastatin is used to lower high cholesterol (LDL and total cholesterol) and triglycerides, while raising HDL (“good”) cholesterol. It is also prescribed to reduce the risk of heart attack, stroke, and other cardiovascular events in patients with coronary heart disease, diabetes, or other risk factors. It belongs to the statin class of medications and is one of the most widely prescribed cholesterol-lowering drugs worldwide.
The most commonly reported side effects include muscle pain or weakness (myalgia), headache, dizziness, and gastrointestinal symptoms such as nausea, constipation, flatulence, and abdominal pain. Most side effects are mild and may resolve on their own. However, if you experience unexplained muscle pain, tenderness, or weakness, especially with dark-coloured urine or fever, contact your doctor immediately as this may indicate a serious condition called rhabdomyolysis.
No, you should avoid grapefruit juice while taking simvastatin. Grapefruit juice inhibits the CYP3A4 enzyme in the gut and liver, which is responsible for breaking down simvastatin. This can significantly increase simvastatin levels in your blood, raising the risk of serious side effects including muscle damage (rhabdomyolysis). This interaction can occur even with small amounts of grapefruit juice.
Simvastatin should be taken in the evening, because cholesterol production in the liver is highest during the night. Simvastatin has a relatively short half-life (about 1–3 hours for the active form), so evening dosing ensures peak drug activity coincides with peak cholesterol synthesis. You can take it with or without food. Try to take it at the same time each evening to maintain a consistent routine.
No, simvastatin is strictly contraindicated during pregnancy and breastfeeding. Cholesterol and its biosynthetic intermediates are essential for normal foetal development, and inhibiting their synthesis may pose risks to the unborn child. Women of childbearing potential should use reliable contraception while taking simvastatin. If you become pregnant while on simvastatin, stop the medication immediately and contact your doctor.
Both simvastatin and atorvastatin are statins that lower cholesterol by inhibiting HMG-CoA reductase. Key differences include: (1) Potency – atorvastatin is generally more potent at equivalent milligram doses; (2) Timing – simvastatin must be taken in the evening, while atorvastatin can be taken at any time of day due to its longer half-life; (3) Drug interactions – simvastatin is more susceptible to CYP3A4-mediated interactions; (4) Maximum dose – the 80 mg dose of simvastatin has been restricted due to muscle safety concerns, while atorvastatin 80 mg remains widely used. Your doctor will choose the most appropriate statin based on your individual needs.
References
All medical information is based on peer-reviewed research and international clinical guidelines. Evidence Level 1A.
- Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). The Lancet. 1994;344(8934):1383-1389. doi:10.1016/S0140-6736(94)90566-5
- Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals. The Lancet. 2002;360(9326):7-22. doi:10.1016/S0140-6736(02)09327-3
- Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias. European Heart Journal. 2020;41(1):111-188. doi:10.1093/eurheartj/ehz455
- Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. Journal of the American College of Cardiology. 2019;73(24):e285-e350. doi:10.1016/j.jacc.2018.11.003
- European Medicines Agency (EMA). Simvastatin – Summary of Product Characteristics (SmPC). EMA/CHMP. Available at: www.ema.europa.eu. Accessed February 2026.
- U.S. Food and Drug Administration (FDA). Simvastatin – FDA-Approved Labeling. Available at: www.accessdata.fda.gov. Accessed February 2026.
- National Institute for Health and Care Excellence (NICE). Cardiovascular disease: risk assessment and reduction, including lipid modification. Clinical guideline CG181. Updated 2023.
- World Health Organization. WHO Model List of Essential Medicines – 23rd List, 2023. Geneva: WHO; 2023.
- Collins R, Reith C, Emberson J, et al. Interpretation of the evidence for the efficacy and safety of statin therapy. The Lancet. 2016;388(10059):2532-2561. doi:10.1016/S0140-6736(16)31357-5
- British National Formulary (BNF). Simvastatin. NICE/BNF. Available at: bnf.nice.org.uk. Accessed February 2026.
Medical Editorial Team
This article has been written and reviewed by our team of medical specialists following international clinical guidelines and evidence-based medicine principles.
Medical Content Team
Licensed physicians specialising in clinical pharmacology and cardiology. All content follows WHO, EMA, FDA, and NICE guidelines with GRADE evidence framework Level 1A.
Medical Review Board
Independent panel of medical experts who review all content for accuracy, completeness, and adherence to current international treatment guidelines and evidence-based medicine standards.
Editorial Standards: No commercial funding or pharmaceutical advertising. All medical claims supported by peer-reviewed evidence. Content reviewed at least annually. Published: August 1, 2025. Last reviewed: February 9, 2026.