The common causes of leg cramps even after taking calcium tablets are low blood calcium status and muscle strain, as follows: 1. Low blood calcium status: It is possible that after taking calcium tablets, blood calcium has not risen to a normal level and is still in a low blood calcium status. The majority of leg cramps are caused by low calcium, and in the first few days of calcium supplementation, blood calcium may still be on the rise, and has not fully reached the normal level, so cramping symptoms may also recur. 2, muscle strain: leg cramps may not be caused by calcium deficiency, such as leg cramps can also be seen in too much sports, excessive intensity of sports can cause strain and injury to the gastrocnemius muscle. A large amount of lactic acid will accumulate in the calf, so at night also easy to cause cramps in the calf.