Vicky, my brother has the same problem and the doctor presribed 500mg capsules called Doxium Fuerte, they are actually 500mg capsules of calcium, I believe they are available over the counter at the farmacia. Of course it may be that your father has a blood circulation problem, particularly if he has any pain or numbness in his legs, he should visit his doctor.

Thank you Roger, much appreciated. He hasn't got any pain he says just an ache quite regularly. I will try these capsules and see if they help. Thank you again.

Its possible he is not drinking enough water... and as someone else pointed out maybe its hhis circulation in which case he should visit a Dr. Believe this or not but it does work as in the summer I sometimes get cramp in bed at night - buy a bottle of Alcohol from any farmacy or Mercadona ( not the stuff you drink ) and throw it over the cramp as soon as it starts, and it goes. A bit hard in a restaurant I know. My local Medico advised me of this .... tell Dad to try it...

The pharmacist advised my 2 children, 25 and 27 to try quinine sulphate tablets when they were getting cramps during football BUT as Souxie says, plenty of water with them.. Mention those to the docs when you go. Steve and Cath

Tonic water helps too if you can drink it on its own without the gin xx

Tonic water contains quinine

could be sciatica,I used to get it when I would drive from UK to Spain,it would be in the thigh muscle and come on when sitting in the same position,doc never prescribed any medication just massage and light exercise,took a few years but eventually cleared up,,if the cramp is in the calf,when I played football this was common and we had salt tablets, (don't overdo the salt) good luck.

A lack of Potassium is another cause. Doctor prescribed tablets for this. Tonic water is a good way of taking small quantities of quinine, another well recorded cure. I would always recommend speaking to your doctor before any self medication, there may be underlying causes especially if blood circulation in the legs is not too good, or if suffer from varicose veins.