Heat

• In a study conducted in the Netherlands conducted by the pharmaceutical company Organon, some of the women using estriol cream felt a "vaginal heat" in the first days of use.
  
  

Allergy

• New allergies can occur at any time. If you develop a rash, burning or itching while using topical estriol, contact a health care professional.
  
  

Inactive Ingredients

• The Food and Drug Administration has not approved and does not regulate any products containing estriol so inactive ingredients are not mandated to be the same in every cream. Unexpected ingredients could possibly cause side effects.
  
  

Considerations

• Estriol may raise your risk of breast cancer. Studies have been conflicting as to whether or not this risk is more or less than it is with standard HRT.
  
  

Warning

• If you have any unusual or life-threatening (such as difficulty breathing or chest pain) while taking estriol, seek immediate medical attention.