What disease-modifying therapy (DMT) for multiple sclerosis (MS) is teratogenic to males?

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Last updated: April 16, 2025 • View editorial policy

From the Guidelines

Teriflunomide is not mentioned in the provided evidence as a disease-modifying therapy (DMT) for multiple sclerosis that is teratogenic to males, however, Cyclophosphamide and Thalidomide are strongly recommended to be discontinued in men prior to attempting conception due to their potential teratogenic effects. According to the 2020 American College of Rheumatology guideline for the management of reproductive health in rheumatic and musculoskeletal diseases 1, Cyclophosphamide may impair spermatogenesis or be mutagenic for DNA, and should be discontinued 3 months prior to attempting conception. Thalidomide is detectable in seminal fluid and is strongly teratogenic when given to pregnant women, and should be discontinued at least 1 month prior to attempting conception.

Key Points to Consider

  • The evidence provided does not directly address the teratogenic potential of DMTs for multiple sclerosis in males, but it does discuss the potential risks associated with certain medications used in rheumatic and musculoskeletal diseases.
  • Cyclophosphamide and Thalidomide are identified as medications that should be discontinued in men prior to attempting conception due to their potential teratogenic effects 1.
  • The guideline recommends continuation of certain medications, such as Hydroxychloroquine, azathioprine, and tumor necrosis factor inhibitors, in men with rheumatic and musculoskeletal diseases who are planning to father a child 2.

Recommendations for Clinical Practice

  • Men with multiple sclerosis who are taking medications that may be teratogenic, such as Cyclophosphamide or Thalidomide, should discontinue these medications prior to attempting conception.
  • Healthcare providers should discuss the potential risks and benefits of medication use with male patients who are planning to father a child, and consider alternative treatment options if necessary.
  • Further research is needed to fully understand the potential teratogenic effects of DMTs for multiple sclerosis in males, and to inform evidence-based guidelines for clinical practice.

From the Research

Disease-Modifying Therapies (DMTs) for MS and Teratogenic Effects on Males

  • There is limited research on the teratogenic effects of DMTs for MS on males, as most studies focus on female fertility and pregnancy outcomes 3, 4.
  • One study found that mitoxantrone, a DMT used to treat aggressive MS, does not affect reproductive capacity or pregnancy outcomes in patients with MS, including males 5.
  • A scoping review on male sexual and reproductive health in MS found that there may be a relationship between MS and male infertility, but changes in sexual behavior may underlie this association 6.
  • Another study analyzed data from the Andalusian Registry of Pregnancies in patients with MS and found that MS does not affect the fertility of men, and the use of a DMT at the time of conception does not affect their fertility or their children's health 7.

Specific DMTs and Teratogenic Effects

  • Mitoxantrone: no teratogenic effects on males 5.
  • Other DMTs: limited research on teratogenic effects on males, but no association found between DMT use and risk of miscarriage, prematurity, or low birth weight in offspring 7.

Gaps in Research

  • Limited studies on the reproductive issues unique to men with MS, including the effects of DMTs on male fertility and reproductive health 3, 6.
  • Need for further research on the priorities for future research, including the effects of DMTs on gonadal function in men with MS 3.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.