Nocturnal leg cramps more common in summer
According to researchers from Canada, prescriptions for quinine and internet searches related to leg cramps were both seasonal, with highs in mid-summer and lows in mid-winter.
Researchers looked at the number of new quinine prescriptions for adults older than 50 in British Columbia, Canada, from 2001 to 2007. There were 31,339 people, of whom 61% were female, who began taking quinine during the six-year study period.
Over the same period, Google Trends data from Australia and the US — where the seasons are reversed — on the search term “leg cramps”, revealed a similar annual cycle, peaking in the warmer months and dropping to their minimum in winter.
The authors noted that during the study period drug regulatory bodies in Australia, the US and New Zealand began warning against using quinine for the treatment of nocturnal leg cramps after reports of serious adverse events, most notably thrombocytopenia and cardiac arrythmias.