Interaction Details

Fosphenytoin is classified as belonging to the following category: Anticonvulsants

Theoretically, taking lithium supplements with anticonvulsants might increase the risk of neurotoxicity.
Drugs such as carbamazepine and phenytoin seem to increase the risk of neurotoxicity. It is unclear if this interaction would occur with the smaller doses found in lithium supplements.

Interaction Rating


Likelihood of Occurrence


Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists


  • Martindale W. Martindale the Extra Pharmacopoeia. Pharmaceutical Press, 1999.
  • McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

Lithium Overview

Lithium Lithium is a chemical element and a type of metal that is present in the diet. It is available as a prescription drug, FDA-approved for the treatment of bipolar disorder. It is also found in some supplement products in small amounts in various forms (e.g., lithium orotate) to help support healthy mental function.
See More Information Regarding Lithium

Fosphenytoin Overview

  • Fosphenytoin injection is used to treat primary generalized tonic-clonic seizures (formerly known as a grand mal seizure; seizure that involves the entire body) and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system. Fosphenytoin injection may also be used to control certain type of seizures in people who cannot take oral phenytoin. Fosphenytoin is in a class of medications called anticonvulsants. It works by decreasing abnormal electrical activity in the brain.

See More Information Regarding Fosphenytoin Injection

Lithium - More Interactions

Lithium interacts with 511 drugs

Interaction Rating Key

These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.

Major The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur.
Moderate Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur.
Minor Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction.
Unknown No interactions have been reported or no interaction data is currently available.

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Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Drug descriptions are provided by MedlinePlus.

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