Is there a link between seizures and the use of Mirena (levonorgestrel) IUD?

Seizures and Mirena IUD: No Direct Causal Link Established

There is no established research linking Mirena (levonorgestrel) IUD to causing seizures. The available evidence addresses drug interactions between anticonvulsant medications and the Mirena IUD in women who already have epilepsy, but does not suggest that the Mirena IUD itself triggers or causes seizures.

Key Evidence from Guidelines

Safety in Women with Epilepsy

• The CDC Medical Eligibility Criteria classifies anticonvulsant therapy use with the levonorgestrel IUD as Category 1 (no restriction for use), indicating that women taking seizure medications can safely use the Mirena IUD 1.

• Limited evidence specifically demonstrates that certain anticonvulsants (phenytoin, carbamazepine, barbiturates, primidone, topiramate, oxcarbazepine) do not interfere with the contraceptive effectiveness of the LNG-IUD 1.

• No drug interactions have been reported among epileptic women taking lamotrigine and using the LNG-IUD 1.

Research Evidence in Women with Epilepsy

Prospective Studies Show Safety

• A 2016 prospective pilot study of 20 women with well-controlled epilepsy found that the levonorgestrel IUD did not worsen seizure control 2. In this study:

  • Seizure frequency worsened in 3 women, remained unchanged in 13, and improved in 4 after IUD insertion 2
  • Subjectively, no participant believed the IUD worsened her seizure control 2
  • All participants were satisfied with the IUD and continued use at 6 months 2

• A 2019 pilot study of 20 women with epilepsy using the LNG-IUD showed stable levonorgestrel concentrations and normal bleeding patterns regardless of antiepileptic drug regimen, with no reports of seizure-related adverse effects 3.

Important Distinction: Drug Interactions vs. Seizure Causation

The Real Concern is Contraceptive Failure, Not Seizures

• The documented interaction between anticonvulsants and hormonal contraceptives relates to enzyme-inducing anticonvulsants reducing contraceptive efficacy, not the contraceptive causing seizures 4, 5.

• Phenobarbital, phenytoin, carbamazepine, oxcarbazepine, felbamate, and topiramate increase metabolism of hormonal contraceptives, potentially leading to contraceptive failure 5.

• However, this interaction primarily affects oral contraceptives and levonorgestrel implants (Norplant), not the levonorgestrel IUD 1, 2.

Why the IUD is Different

• The levonorgestrel IUD delivers hormone locally to the uterus with minimal systemic absorption, making it less susceptible to drug interactions compared to oral contraceptives 2, 3.

• Studies show that AED trough concentrations remain stable after IUD insertion, and the IUD does not meaningfully affect anticonvulsant drug levels 2.

Clinical Bottom Line

If a woman without epilepsy develops seizures after Mirena insertion, investigate other causes rather than attributing it to the IUD. The levonorgestrel IUD has not been shown to lower seizure threshold or cause seizures in women without pre-existing epilepsy. The only reported adverse reactions in the literature include urticaria and other allergic-type reactions, not neurological events 6.

For women with epilepsy, the Mirena IUD is considered a safe and effective contraceptive option that does not worsen seizure control 1, 2, 3.