Quinine for muscle cramps linked to increased mortality

Long-term use of quinine for nocturnal leg cramps may increase the risk of mortality, a study of UK GP prescribing published in JAMA has found.

Quinine has been used in the UK for the treatment of nocturnal leg cramps for many years. | SCIENCE PHOTO LIBRARY
Quinine has been used in the UK for the treatment of nocturnal leg cramps for many years. | SCIENCE PHOTO LIBRARY

Researchers from the UK and France used data from the Health Improvement Network database from general practices in the UK. Of 175,195 patients included in their analysis, approximately a quarter (44,699) had been prescribed quinine for idiopathic muscular cramps or restless leg syndrome for at least one year.

The median daily quinine dose was 203mg. Over a median follow-up period of 5.7 years, quinine exposure was associated with 4.2 deaths per 100 person–years, compared with a rate of 3.2 deaths per 100 person–years for unexposed individuals (adjusted hazard ratio 1.24, CI 1.21–1.27). These findings suggest the risk of death could be significantly increased with long-term use of quinine.

Poor risk–benefit ratio

The authors acknowledge that their findings could reflect unmeasured confounders that may predispose patients to higher mortality. However, they concluded, "the benefits of quinine in reducing cramps should be balanced against the risks."

Owing to the poor benefit-to-risk ratio, both NICE CKS and the MHRA advise that quinine should not be considered a routine treatment for nocturnal leg cramps, and should only be considered when self-care measures fail and cramps cause regular disruption of sleep.

If GPs choose to prescribe quinine for this indication, CKS recommends a dose of 200–300mg at bedtime for 4–6 weeks. If this is beneficial, treatment may be continued with review every 3–6 months.

Want news like this straight to your inbox?
Sign up for our bulletins

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Already registered?
Sign in

Register or Subscribe to MIMS

GPs can get MIMS print & online and GPonline for free when they register online – take 2 minutes, and make sure you get your free MIMS access! If you're not a GP, you can subscribe to MIMS for full access.

Register or subscribe

MIMS Dermatology

Read the latest issue online exclusively on MIMS Learning.

Read MIMS Dermatology

MIMS Adviser

Especially created for prescribing influencers.

Request free copy

Mobile apps

MIMS: access the full drug database and quick-reference tables on the go

MIMS Diagnosis and Management: concise information on signs and symptoms, investigations and diseases