Skip to main content

Belzutifan Pregnancy and Breastfeeding Warnings

Medically reviewed by Last updated on Nov 16, 2021.

Belzutifan is also known as: Welireg

Belzutifan Pregnancy Warnings

Animal studies have revealed evidence of embryotoxicity and embryolethality. There are no controlled data in human pregnancy.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.

Use should be avoided.

US FDA pregnancy category: Not assigned.

Risk Summary: Based on findings in animal studies, this drug can cause fetal harm when administered during pregnancy. Oral administration to pregnant rats during organogenesis caused embryolethality, reduced fetal body weight, and fetal skeletal malformations at maternal exposures greater than or equal to 0.2 times the equivalent human dose.

-This drug can harm a developing fetus.
-Adequate methods of contraception should be encouraged.
-Verify negative pregnancy status in females of reproductive potential prior to initiating therapy.
-If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus.
-Advise females of reproductive potential to use effective nonhormonal contraception during therapy and for 1 week after.
-This drug can render some hormonal contraceptives ineffective.
-Advise males with female partners of reproductive potential to use effective contraception during therapy and for 1 week after.
-This drug may impair fertility in males and females of reproductive potential.

See references

Belzutifan Breastfeeding Warnings

Use should be avoided.

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

Comments: Because of the potential for serious adverse reactions in a breastfed child, advise women not to breastfeed during therapy with this drug and for 1 week after.

See references

References for pregnancy information

  1. "Product Information. Welireg (belzutifan)." Merck & Company Inc (2021):

References for breastfeeding information

  1. "Product Information. Welireg (belzutifan)." Merck & Company Inc (2021):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.