Quinine and Leg Cramps

Muscle cramp or leg cramp is a recurrent and painful condition and a common complaint among the elderly. It is commonly nocturnal and can disturb a good night's sleep. No specific cause can be identified and therapy is mostly symptomatic.

Quinine sulfate (200-300 mg at bedtime) is widely used as an effective therapy for idiopathic nocturnal leg cramps[1]. Several studies have questioned the effectiveness of quinine in leg cramps, whereas other studies have shown significantly more benefit with use of quinine in reducing the frequency and severity of cramps compared with placebo or vitamin E.

However, the mechanism of this effect is obscure. Quinine appears to decrease the excitability of the motor end plate, thereby reducing the muscle contractility.

New research has found that long term use of quinine, prescribed off label for leg cramps, muscle cramps or restless leg syndrome, is associated with increased mortality[2]. Therefore, it is not recommended for routine treatment and is advised only when cramps are very painful or frequent.

[1] Mandal et al: Is quinine effective and safe in leg cramps? In Journal of Clinical Pharmacology – 1995
[2] Wise: Long term quinine for muscle cramps may increase death risk in British Medical Journal - 2017