How Calcium interacts with Anticonvulsants

Interaction type: Depletions

Interaction rating: Proven

Studies have shown that these drugs interfere with vitamin D metabolism, which results in decreased absorption of calcium. Supplementation with the affected nutrient may be necessary. (1) (2) (3)

These drugs include phenytoin, carbamazepine, primidone, gabapentin, valproic acid, felbamate, lamotrigine, mephenytoin, fosphenytoin, clonazepam, ethosuximide, diazepam, clorazepate dipotassium, levatiracetam, tiagabine, topiramate, methsuximide, phensuximide, trimethadione, magnesium sulfate, acetazolamide, oxcarbazepine, zonisamide, ethotoin


  1. View Abstract: Shafer RB, et al. Calcium and Folic Acid Absorption in Patients Taking Anticonvulsant Drugs. J Clin Endocrinol Metab. Dec1975;41(06):1125-29.
  2. View Abstract: Foss MC, et al. The Effect of the Anticonvulsants Phenobarbital and Diphenylhydantoin on Intestinal Absorption of Calcium. Acta Physiol Lat Am. 1979;29(4-5):223-28.
  3. View Abstract: Winnacker JL, Yeager H, Saunders JA. Rickets in children receiving anticonvulsant drugs. Biochemical and hormonal markers. Am J Dis Child. Mar1977;131(3):286-90.