Health Guide


What is it?

Indole-3-Carbinol is a dietary supplement that is used to treat breast cancer. It may be used to treat certain diseases that seem to go away, but return after a time. These diseases include respiratory papillomatosis (pap-i-lo-mah-TO-sis) (RRP) and systemic lupus (LOO-pus) erythematosus (err-i-the-mah-TOH-sus) ("lupus").

Other names for Indole-3-Carbinol include: I3C, Indole, and Indole-3-Methanol.

Ask your doctor, nurse, or pharmacist if you need more information about this medicine or if any information in this leaflet concerns you.

Before Using:

Tell your doctor if you...

  • are taking medicine or are allergic (uh-LER-jik) to any medicine (prescription or over-the-counter (OTC) or dietary supplement)
  • are pregnant or plan to become pregnant while using this medicine
  • are breast feeding
  • have other health problems, such as high blood pressure or heart or blood vessel disease


Talk with your caregiver about how much Indole-3-Carbinol you should take. The amount depends on the strength of the medicine and the reason you are taking it. If you are using this medicine without instructions from your caregiver, follow the directions on the medicine bottle. Do not take more medicine or take it more often than the directions tell you to.

To store this medicine:

Keep all medicine locked up and away from children. Store medicine away from heat and direct light. Do not store your medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down and not work the way it should work. Throw away medicine that is out of date or that you do not need. Never share your medicine with others.


  • Before taking Indole-3-Carbinol, tell your doctor if you are pregnant or breast feeding

Side Effects:

Stop taking your medicine right away and talk to your doctor if you have any of the following side effects. Your medicine may be causing these symptoms which may mean you are allergic to it.

  • Breathing problems or tightness in your throat or chest
  • Chest pain
  • Skin hives, rash, or itchy or swollen skin

Other Side Effects:

You may have the following side effects, but this medicine may also cause other side effects. Tell your doctor if you have side effects that you think are caused by this medicine.

  • Increased blood cholesterol (ko-LES-ter-ol) level (fat in your blood) (3)
  • Slight increase in the number and amount of bowel movements (3)
  • Decreased constipation (hard stools) (3)
  • Liver problems (in animals) (4)
  • Skin rash (5)


1. Katchamart S & Williams DE: Indole-3-carbinol modulation of hepatic monooxygenases CYP1A1, CYP1A2 and FMO1 in guinea pig, mouse, and rabbit. Comp Biochem Physiol 2001; 129(4):377-384.

2. Larsen-Su & Williams DE: Dietary indole-3-carbinol inhibits FMO activity and the expression of flavin-containing monoooxygenase form 1 in rat liver and intestine. Drug Metab Dispos 1996; 24(9):927-931.

3. Bradlow HL, Michnovicz JJ, Halper M et al: Long-term responses of women to indole-3-carbinol or a high fiber diet. Cancer Epidemiol Biomarkers Prev 1994; 3(7):591-595.

4. Verhoeven DTH, Verhagen H, Goldbohm RA et al: A review of mechanisms underlying anticarcinogenicity by brassica vegetables. Chem Biol Interact 1997; 103(2):79-129.

5. McAlindon TE, Gulin J, Chen T et al: Indole-3-carbinol in women with SLE: effect on estrogen metabolism and disease activity. Lupus 2001; 10(11):779-783.

Last Updated: 7/4/2018
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