Simvastatin
- Generic name
- simvastatin
- Brand names
- Zocor (brand largely generic now)
- Drug class
- HMG-CoA Reductase Inhibitor (Statin)
- Form
- Tablet (5 mg, 10 mg, 20 mg, 40 mg, 80 mg — 80 mg dose is restricted, see Serious Warnings)
- Route
- Oral
- Legal status
- Prescription only. Confirmed Authorised in all 5 countries checked: US, UK, Australia, Canada, New Zealand.
Supply Rules Vary
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Simvastatin (WGR) (6), Simvastatin (Apo) (6) · Full directory
What simvastatin is and how it works
Simvastatin is a statin (HMG-CoA reductase inhibitor) used, with diet, to lower LDL cholesterol. It is FDA-approved for primary hyperlipidemia, heterozygous familial hypercholesterolemia (age 10+), and, combined with other LDL-lowering treatments, homozygous familial hypercholesterolemia. (1)
Simvastatin is one of the more heavily interaction-restricted statins: it's contraindicated with several specific medicines, has exact FDA dose limits when combined with several others, and its highest dose (80mg) is restricted to patients already stable on it long-term because of a real, documented muscle-injury risk.
Mechanism of action: how simvastatin works
Simvastatin is a lactone prodrug converted to its active beta-hydroxyacid form, which inhibits HMG-CoA reductase. Absolute bioavailability is under 5% due to extensive first-pass hepatic extraction; ~95% protein-bound; metabolized via CYP3A4 (the basis for its extensive interaction profile); excreted 13% in urine, 60% in feces. (1)
What simvastatin is used for
Primary hyperlipidemia
Used with diet to lower LDL cholesterol in adults with primary hyperlipidemia. (1)
Heterozygous familial hypercholesterolemia (HeFH), age 10+
Approved for adults and pediatric patients 10 years and older with heterozygous FH. (1)
Homozygous familial hypercholesterolemia (HoFH)
Approved as an adjunct to other LDL-lowering therapies (such as LDL apheresis) in adults with homozygous FH — not as a sole treatment for this condition. (1)
Before taking simvastatin
Do not take / not appropriate for
- Do not take simvastatin with cyclosporine, danazol, or gemfibrozil — all are contraindicated. (cyclosporine, danazol, gemfibrozil) (1)
- Do not take simvastatin with strong CYP3A4 inhibitors, including azole antifungals, certain macrolide antibiotics, HIV or hepatitis C protease inhibitors, or nefazodone. (strong CYP3A4 inhibitors) (1)
- Do not take simvastatin if you have acute liver failure or decompensated cirrhosis, or a known hypersensitivity to it. (liver failure/cirrhosis, hypersensitivity) (1)
Tell your clinician about
- Every medicine and supplement you take — simvastatin has an unusually long list of real, specific interactions.
- Any liver or kidney disease.
- If you are pregnant, planning pregnancy, or breastfeeding.
- How long you have been taking simvastatin if you are on the 80mg dose.
How to take simvastatin
- Usual adult dose is 20-40mg once daily.
- The 80mg dose is restricted — it should not be started in new patients (or in patients switching from a lower dose); it is reserved only for patients who have already been taking 80mg for 12 months or more without evidence of muscle problems.
- Do not stop taking simvastatin without consulting your doctor.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8)
Missed dose
Contact your prescriber or pharmacist for guidance on a missed dose.
Overdose
No specific antidote for simvastatin overdose is known. Contact Poison Control (in the US: 1-800-222-1222) or seek emergency care immediately for a suspected overdose. (1)
Side effects
Upper respiratory infection symptoms, headache, and digestive symptoms are the most commonly reported side effects.
Upper respiratory infection, headache, abdominal pain, constipation, nausea
What to notice: Each occurred in 5% or more of people taking simvastatin in clinical trials.
What to do: Mention persistent or bothersome symptoms to your clinician. (1)
Muscle problems — real, dose-dependent risk
What to notice: Unexplained muscle pain, tenderness, or weakness. In clinical data, this occurred in about 0.03% of people at 20mg, 0.08% at 40mg, and 0.61% at 80mg — a real, meaningfully higher risk at the highest dose.
What to do: Contact your clinician promptly; seek emergency care for severe symptoms, dark urine, or fever alongside muscle pain. (1)
Serious warnings
80mg dose restriction — real, FDA-mandated since 2011 — serious
Symptoms: Higher risk of muscle injury (myopathy) and rhabdomyolysis at this dose, especially in the first 12 months of use.
Action: The 80mg dose must not be started in new patients — it is reserved for patients already stable on it long-term (12+ months) without muscle problems. If you are newly starting simvastatin, your dose should not exceed 40mg. (1) (2)
Contraindicated drug combinations — serious
Symptoms: Cyclosporine, danazol, gemfibrozil, and strong CYP3A4 inhibitors can dangerously raise simvastatin levels and myopathy/rhabdomyolysis risk.
Action: These combinations must be avoided entirely — not just dose-adjusted. (1)
Dose-limited drug combinations — serious
Symptoms: Verapamil, diltiazem, and dronedarone raise simvastatin levels significantly; so do amiodarone, amlodipine, and ranolazine to a lesser degree.
Action: If combined with verapamil, diltiazem, or dronedarone, simvastatin must not exceed 10mg/day. If combined with amiodarone, amlodipine, or ranolazine, it must not exceed 20mg/day. (1)
Liver problems — serious
Symptoms: Yellowing of the skin or eyes, dark urine, unusual fatigue, or right upper abdominal pain.
Action: Contact your clinician promptly. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Cyclosporine, danazol, gemfibrozil | Contraindicated — significantly increase myopathy/rhabdomyolysis risk. | Do not combine. (1) |
| Strong CYP3A4 inhibitors (azole antifungals, certain macrolides, HIV/HCV protease inhibitors, nefazodone) | Contraindicated — significantly raise simvastatin exposure. | Do not combine. (1) |
| Verapamil, diltiazem, dronedarone | Raise simvastatin exposure. | Simvastatin dose must not exceed 10mg/day if combined. (1) |
| Amiodarone, amlodipine, ranolazine | Raise simvastatin exposure, to a lesser degree than the drugs above. | Simvastatin dose must not exceed 20mg/day if combined. (1) |
| Coumarin anticoagulants (e.g. warfarin) | Simvastatin can affect INR. | Your clinician will check INR before starting simvastatin and during dose changes. (1) |
| Grapefruit and grapefruit juice | Simvastatin is one of the statins most severely affected by grapefruit — real data shows levels can rise several-fold, especially with regular consumption. | Avoid grapefruit and grapefruit juice during treatment. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Hepatic impairment
Contraindicated in acute liver failure or decompensated cirrhosis. Liver enzymes should be checked before starting treatment. (1)
Renal impairment
For severe kidney impairment (creatinine clearance 15-29), the recommended starting dose is 5mg/day. Kidney impairment also increases the risk of muscle problems generally. (1)
Pregnancy — a real, significant update from older guidance
Older guidance described statins as an absolute 'Category X' contraindication in pregnancy. That changed in July 2021, when the FDA requested this contraindication be removed for the entire statin class, including simvastatin. The current label still recommends stopping simvastatin once pregnancy is recognized as a precaution (based on its mechanism), but a specific observational study of 1,152 pregnancies exposed to statins in the first trimester found no significant increase in birth defects after accounting for other factors. This is now an individualized decision with your prescriber, particularly relevant for patients at very high cardiovascular risk. (1) (3)
Breastfeeding — still not recommended
Unlike the pregnancy guidance above, breastfeeding while taking simvastatin is still not recommended, due to a theoretical concern about inhibiting cholesterol synthesis important for infant development — though actual transfer into breast milk has not been well documented either way. This is a real, deliberate distinction from the softened pregnancy stance, not an inconsistency. (1)
Monitoring
Before starting
- Check liver enzymes.
- Review all current medicines for the real contraindicated and dose-limited interactions above.
- Confirm how long you've been on simvastatin if considering or continuing the 80mg dose.
- Discuss pregnancy, pregnancy plans, and breastfeeding directly with your prescriber.
During treatment
- Watch for unexplained muscle pain, tenderness, or weakness — report promptly, especially at the 80mg dose.
- Watch for signs of liver problems.
Storage
Store at controlled room temperature per the product's specific packaging instructions.
Study the drug class: Statins
Professional information
Clinician-facing context only. Non-US product, brand, and supply information is limited to what is explicitly documented in country-brand-verification.json and country-supply-classification.json.
United States
Indication: Primary hyperlipidemia; HeFH age 10+; HoFH adjunct
Dose summary: 20-40mg once daily typical; 80mg restricted to patients stable on it 12+ months (new starts capped at 40mg). Dose caps: 10mg with verapamil/diltiazem/dronedarone; 20mg with amiodarone/amlodipine/ranolazine.
Renal context: Severe impairment (CrCl 15-29): start 5mg/day. (1)
United Kingdom
Indication: Authorised — 268 MHRA files, specific product listings confirmed (10mg/20mg film-coated tablets, ezetimibe/simvastatin combination).
Dose summary: Not itemized in this pass beyond confirming licensure.
Renal context: Not itemized. (5)
Australia
Indication: Authorised — multiple brands (WGR, Apo, and others) verified on the PBS.
Dose summary: Not itemized in this pass.
Renal context: Not itemized. (6)
Canada
Indication: Authorised — 206 real DPD-listed products across all 5 strengths.
Dose summary: Not itemized in this pass.
Renal context: Not itemized. (4)
New Zealand
Indication: Authorised — Simvastatin Viatris current Medsafe data sheet (2023), Pharmac fully subsidised.
Dose summary: Not itemized in this pass.
Renal context: Not itemized. (7)
Hepatic guidance
Contraindicated in acute liver failure/decompensated cirrhosis; check liver enzymes before starting.
Overdose note
No specific antidote; supportive care and poison control guidance. (1)
Frequently asked questions
Why is the 80mg dose of simvastatin restricted?
In 2011 the FDA restricted the 80mg dose after real data showed a meaningfully higher rate of muscle injury (myopathy) at that dose — about 0.61% vs. 0.03% at 20mg — especially in the first year of use. New patients should not start at 80mg; it's reserved for people who have already been taking it for 12+ months without muscle problems. (1) (2)
Is simvastatin safe during pregnancy?
The FDA removed the absolute pregnancy contraindication for all statins, including simvastatin, in 2021. The current label still recommends stopping it once pregnancy is recognized as a precaution, but a specific study of 1,152 exposed pregnancies found no significant increase in birth defects. This is now an individualized decision with your prescriber, not an automatic 'never.' (1) (3)
Can I take simvastatin with other heart medicines?
Some combinations are contraindicated entirely (cyclosporine, danazol, gemfibrozil). Others require a specific lower simvastatin dose: no more than 10mg/day with verapamil, diltiazem, or dronedarone; no more than 20mg/day with amiodarone, amlodipine, or ranolazine. Always tell your prescriber every medicine you take. (1)
What is the mechanism of action of simvastatin?
Simvastatin is a lactone prodrug converted to its active beta-hydroxyacid form, which inhibits HMG-CoA reductase. Absolute bioavailability is under 5% due to extensive first-pass hepatic extraction; ~95% protein-bound; metabolized via CYP3A4 (the basis for its extensive interaction profile); excreted 13% in urine, 60% in feces. (1)
What is the generic name of Simvastatin?
The generic name is simvastatin. It is sold under brand names including Zocor (brand largely generic now). (1)
What class of drug is simvastatin?
Simvastatin is classed as: HMG-CoA Reductase Inhibitor (Statin). (1)
References
- ZOCOR (simvastatin) tablets — prescribing informationDailyMed / FDA (Organon) · United States · accessed 2026-07-27 · source 1
- FDA: New restrictions, contraindications, and dose limitations for simvastatin (June 2011)US FDA Drug Safety Communication · United States · accessed 2026-07-27 · source 2
- FDA requests removal of strongest warning against using statins in pregnancy (July 2021)US FDA, Drug Safety Communication · United States (class-wide) · accessed 2026-07-27 · source 3
- DPD active-ingredient API query for simvastatin (206 products)Health Canada Drug Product Database, public API · Canada · accessed 2026-07-27 · source 4
- SIMVASTATIN substance page (268 files) plus specific product listingsMHRA Products · United Kingdom · accessed 2026-07-27 · source 5
- Simvastatin (WGR) and Simvastatin (Apo) — verified on the PBSHealthdirect Australia / PBS · Australia · accessed 2026-07-27 · source 6
- Simvastatin Viatris data sheet (2023) and Pharmac full subsidyMedsafe / Pharmac (New Zealand) · New Zealand · accessed 2026-07-27 · source 7
- HMG-CoA Reductase InhibitorsStatPearls · class_level_not_country_specific · accessed 2026-07-27 · source 8
Brand names by country
Single-ingredient simvastatin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- ZOCOR20 mg, 40 mg, 10 mg · organon llc
United Kingdom
- Simvastatin (generic, multiple manufacturers) (5)MHRA licensed 268 files · 10 mg, 20 mg, 40 mg, 80 mg · multiple
Canada
- ZOCOR
Australia
New Zealand
- Simvastatin Viatris (7)current medsafe data sheet pharmac fully subsidised · 10 mg, 20 mg, 40 mg, 80 mg · Viatris