Statin-induced myopathy: muscle pain, weakness and what to do

Statins lower cholesterol and, according to the NHS, help prevent heart attacks and strokes in people at higher risk or who already have cardiovascular disease. The NHS lists muscle pain among common side effects, alongside headaches, dizziness, feeling sick, feeling more tired or weaker than usual, wind, bowel upset and sleep problems.

The BHF uses the term statin-associated muscle symptoms (SAMS) for muscle pain, weakness or tenderness in people taking statins. The NHS Genomics Education Programme describes a wider group of muscle-related adverse events from myalgia (muscle pain) through myopathy to statin-induced rhabdomyolysis, known collectively as SAMS. Most cases sit at the mild end: aching, stiffness, tenderness or cramps without serious muscle damage.

The BHF says muscle pain, weakness or tenderness is an uncommon symptom in people taking statins. Research it cites suggests about 11 extra reports of muscle pain and weakness among every 1,000 people in their first year on a statin. It also reports that a 2022 Lancet study found that less than 10 per cent of cases of mild muscle pain or weakness reported by people taking statins were actually caused by the statin, and that a large review found only a handful of symptoms were genuinely linked to statins: certain liver blood-test results (without liver disease), changes in urine composition, and swelling from fluid build-up.

This does not mean your symptoms are imaginary. The BHF stresses that muscle pain and weakness can affect daily life whatever the cause, so you should tell your doctor, who will investigate and help you manage it. Other causes such as an underactive thyroid, low vitamin D, strenuous exercise, other medicines or conditions can produce similar symptoms, and your clinician will think about these.

The BHF explains that people on statins can rarely develop a muscle condition called myopathy, which means the statin needs to be stopped, and very rarely rhabdomyolysis, a muscle condition that requires urgent specialist medical care. Rhabdomyolysis is the breakdown of muscle fibres, releasing substances that can damage the kidneys.

Warning signs include severe or rapidly worsening muscle pain or weakness, marked muscle tenderness, and dark or tea-coloured urine, particularly if you feel generally unwell. Seek urgent medical advice (NHS 111 or A&E) rather than waiting for a routine appointment if these occur. Doctors may check a blood marker called creatine kinase and kidney function to assess severity.

• Severe muscle pain or weakness that is getting worse quickly.

• Dark, tea-coloured urine or passing much less urine.

• Feeling very unwell or feverish with muscle symptoms.

• Any muscle symptoms after starting a new medicine that interacts with your statin.

The NHS warns that statins can cause problems if taken with certain medicines, including some for high blood pressure or blood vessels (such as amlodipine, verapamil or diltiazem), antifungals such as fluconazole, certain antibiotics such as clarithromycin and erythromycin, HIV medicines and warfarin. Always tell prescribers and pharmacists that you take a statin. The BHF notes specific grapefruit advice for some statins: simvastatin should not be taken with grapefruit, whereas atorvastatin allows occasional, not large, amounts.

The Genomics Education Programme explains that some people carry genetic variants in SLCO1B1, CYP2C9 and ABCG2 that increase systemic exposure to statins and the risk of muscle problems. The evidence linking the common SLCO1B1 variant to myopathy is strongest for simvastatin and moderate for atorvastatin, and it is currently uncertain whether the effect is clinically important for rosuvastatin. Genomic testing for these variants is not currently available through the National Genomic Test Directory, so doctors use symptoms, history and clinical judgement instead.

The BHF says your doctor will investigate and help manage any pain with advice on pain relief, exercise and self-care. Self-care tips include paracetamol or ibuprofen if suitable and checked with a pharmacist, gently stretching, warm baths and alternating ice and warm packs, or a physiotherapy referral. Clinicians commonly check for other causes and may review the statin, its dose or whether a different statin suits you, and sometimes pause then re-challenge. Those decisions need a prescriber.

The NHS says to talk to a doctor if you think your medicine is causing side effects, and to talk to a doctor or pharmacist before stopping statins because your cholesterol levels may be affected. Stopping a statin that you need to prevent heart attack or stroke has its own risks, which is why a joint discussion is better than stopping alone. For people who truly cannot tolerate statins, other cholesterol-lowering options exist and your doctor or lipid clinic can explain them.

Start with your GP or pharmacist. Routine checks may include blood tests; severe symptoms need urgent assessment. Lipid clinics in hospitals look after people who cannot tolerate usual statins or have very high cholesterol.

Private cardiologists and lipid specialists can offer review and testing, though genetic testing for statin intolerance is not a standard NHS test and its value for guiding treatment is limited. Ask what any test will change in your treatment.