Medications used to treat multiple sclerosis (MS) can have complex effects on fertility, and some MS drugs may potentially cause infertility or impact reproductive health. However, the relationship between MS medications and infertility is not straightforward and depends on the specific medication, dosage, duration of treatment, and individual patient factors.
Many disease-modifying therapies (DMTs) for MS are designed to modulate or suppress the immune system to reduce disease activity. Some of these medications have known risks related to pregnancy and reproductive health because they can affect rapidly dividing cells or hormonal balance.
For example:
– **Cladribine (Mavenclad)** is contraindicated in pregnant women and those planning pregnancy because it has been shown in animal studies to be embryolethal and cause malformations. Both men and women are advised to use effective contraception during treatment with cladribine due to potential harm to a fetus. While direct evidence of permanent infertility is limited, its effects on DNA suggest possible impacts on reproductive cells[1].
– **Fingolimod (Gilenya)** carries risks of fetal harm if taken during pregnancy. Women are advised against becoming pregnant while taking fingolimod due to observed developmental toxicity in animal studies. It takes about two months for fingolimod clearance from the body after stopping treatment; thus effective contraception is recommended during this period as well[2]. There is no strong evidence that fingolimod causes permanent infertility but its teratogenic potential requires caution around conception.
– **Siponimod (Mayzent)** also shows embryotoxicity and fetotoxicity in animal models with increased rates of fetal abnormalities when exposure occurs during pregnancy. Similar contraceptive precautions apply[3]. Its impact on long-term fertility remains unclear but caution around conception timing is standard practice.
– **Methotrexate**, sometimes used off-label for autoimmune conditions including severe MS symptoms, has a more established link with infertility risk in both men and women due to its mechanism as a folate antagonist affecting cell division including gametes. It can cause temporary or sometimes prolonged infertility; patients are typically advised not only about birth defects but also about possible impaired fertility during treatment[4].
In general:
– Many MS medications require strict contraceptive measures before conception attempts.
– Some drugs may temporarily reduce fertility by affecting hormone levels or ovarian/testicular function.
– The risk of permanent infertility varies widely depending on the drug class; immunomodulators like interferons generally have less impact compared with cytotoxic agents like cladribine or methotrexate.
– Pregnancy outcomes in women with MS may show higher complication rates such as miscarriage or low birth weight compared with non-MS pregnancies; however, this relates partly also to disease activity rather than medication alone[5].
Patients planning families should discuss their specific medication regimen thoroughly with their neurologist or specialist who manages their MS care since balancing disease control against reproductive goals requires individualized assessment.
It’s important that both men and women understand that some treatments might necessitate delaying conception until after drug clearance from the body — often several months — even if there isn’t definitive proof that long-term fertility will be affected permanently.
In summary, while certain multiple sclerosis medications carry risks related specifically to fetal development if taken during pregnancy—and some may influence temporary fertility—there isn’t universal evidence that all MS drugs cause outright permanent infertility. Careful family planning under medical guidance helps minimize risks associated with these powerful therapies while managing multiple sclerosis effectively over time.
