Simvastatin

What is simvastatin?

Simvastatin is used to lower the level of cholesterol (a type of fat) in your blood. When excess cholesterol collects in the walls of your blood vessels, it increases your chance of having a heart attack, or stroke. Lowering cholesterol reduces your risk of heart and blood vessel disease.

Simvastatin works by blocking an enzyme that produces cholesterol in your liver and in this way slows the production of cholesterol in your body. It is in a group of medicines called statins. Read more about statins – when are they used, their benefits and risks and other frequently asked questions about statins.

Dose

• The usual dose of simvastatin is 20 to 40 milligrams once a day.
• Always take your simvastatin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much simvastatin to take, how often to take it, and any special instructions.

How to take simvastatin

• Timing: Take simvastatin once a day, at around the same time each day. You can take simvastatin with or without food.
• Keep taking simvastatin regularly. To reduce your cholesterol effectively, you must keep taking simvastatin every day. 
• Missed dose: If you forget a dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Precautions – before starting simvastatin

• Do you have liver or kidney problems?
• Do you have problems with your thyroid?
• Do you have diabetes?
• Are your trying to get pregnant, think you might be pregnant, you're already pregnant, or you're breastfeeding?
• Do you drink large amounts of alcohol?
• Have you had, or do you have, a muscle disorder?

If any of these apply, it’s important that you tell your doctor or pharmacist before you start pravastatin. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care that your pharmacist will tell you about.

Precautions – when taking simvastatin

• Having large quantities of grapefruit while taking simvastatin can increase your risk of side effects. But, eating no more than half a grapefruit or drinking no more than a standard glass (250ml) of grapefruit juice each day, should not be a problem if you are taking statins.
• You will need to see your doctor regularly when you first start taking simvastatin to make sure the dose is right for you. To get the full benefit of a statin, it is important to keep a healthy diet and exercise often.
• Limit drinking alcohol while you are taking simvastatin. Heavy drinking can increase your risk of serious side effects.

Side effects

Like all medicines, simvastatin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Muscle pain or weakness

Some people will have muscle pain or weakness when taking statins. This is rarely serious and often goes away with time. If your pain comes on shortly after you start your statin, or gets worse, see your doctor. Your doctor will check an enzyme called creatine kinase to see if the aches and pains are possibly being caused or made worse by the statins. If so:

• a lower dose or a different statin may be prescribed, or
• you may choose to continue living with the aches because of the benefits of the statin, or
• you may discuss stopping taking your statin with your doctor.

Your doctor will also want to check for a rare but serious condition called rhabdomyolisis and will check any other medicines you are taking. Rhabdomyolisis can be caused by an interaction between statins and some other medicines including antibiotics.

Increased risk of type 2 diabetes

There is a small chance that statins may increase your risk of getting type 2 diabetes. However, it is usually recommended that people at risk of diabetes do take statins if they are needed to help lower their cholesterol. This is because the overall benefit in health and wellbeing of taking statins and preventing a heart attack or stroke is seen to be greater than the problems from diabetes.

Other side effects

Interactions

Simvastatin can interact with a few medications, including antibiotics, and herbal supplements, so check with your doctor or pharmacist before starting simvastatin or before starting any new medicines or supplements.

Learn more

Medsafe Consumer Information Sheets: Arrow-Simva ; Lipex; Simvastatin Mylan

New Zealand Formulary Patient Information: simvastatin

References

1. Prescribing statins to reduce cardiovascular risk BPAC, 2017
2. Investigating myalgia in patients taking statins BPAC, 2014
3. Statins New Zealand Formulary
4. Simvastatin New Zealand Formulary