• Side effects from Letrozole

    Asked by Saddie on Monday, January 28, 2019

    Side effects from Letrozole

    Very bad facial skin eruptions that turn crusty

    1 Answer from the Community

    • ChicagoSandy's Avatar


      Letrozole works by inhibiting the action of the liver enzyme "aromatase," which is the catalyst for the conversion of the male hormone (androgen) made by the adrenal glands and fat cells (not the fat IN the cells) into estrogen. If the drug is working, you will experience the effects of estrogen deprivation (sort of like menopause-in-overdrive). But because you will be making more androgen than estrogen, you might also experience some effects of androgen dominance: deepening voice, thinning hair, more facial/arm & leg/armpit hair, and oily skin & acne.

      BUT not all skin eruptions are due to the drug's intended anti-estrogen effects. Every version of a given drug, whether brand or generics made by various manufacturers, can contain different inactive ingredients: dyes, excipients, binders, fillers, preservatives, etc. If one maker's version of generic letrozole is giving you skin problems, try one from a different maker. You could very well have sensitivities or even allergies to those inactive ingredients.

      Is it just on one side of your face? Is it painful? Did you have chicken pox as a kid, and have you failed to get the Shingrix or Zostavax shots? If so, it could be shingles, and its timing could be entirely coincidental. Had the eruptions been red w/o pustules or crusts, I'd suspect rosacea (again, a coincidence).

      In any case, talk first to your oncology team (and send them photos if you can), and then go see a dermatologist.

      5 months ago

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