Hormone replacement therapy: Can it cause vaginal bleeding?

I'm taking hormone therapy for menopause symptoms. Recently, I've been experiencing heavy vaginal bleeding with clots. This occurs on a regular monthly basis — similar to a menstrual period. Should I be concerned?

- Jeannine / No state given

Mayo Clinic breast-health specialist Sandhya Pruthi, M.D., and colleagues answer select questions from readers.

Answer

Some forms of hormone therapy for menopause may cause light, monthly bleeding. But hormone therapy should not cause heavy flow with clots, as you have described. This type of bleeding is abnormal and should be evaluated by your physician promptly.

Other potential causes of abnormal bleeding during or after menopause include:

Shrinking or thinning of tissue lining the vagina and uterus due to a decrease in estrogen
Uterine polyps or fibroids
Infections of the uterus, such as endometritis and cervicitis
Abnormal growth of the lining of the uterus (endometrial hyperplasia)
Endometrial cancer

In addition to a careful history and physical examination, laboratory tests and diagnostic procedures may be used to identify the cause of abnormal bleeding in menopausal women.