Drug & supplement interaction

Diindolylmethane + Doxycycline

Doxycycline brand names: Vibra-Tabs, Vibramycin, Doryx, Monodox, Doxycin, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Diindolylmethane and Doxycycline in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Doxycycline states a food rule worth keeping to, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Diindolylmethane and Doxycycline

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Doxycycline and Diindolylmethane in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Diindolylmethane safety at a glance

Diindolylmethane overall Use caution Generally well tolerated in short-term studies, but long-term safety is not well established.
Pregnancy Likely Safe When used orally in amounts commonly found in foods. The typical diet supplies 2-24 mg of diindolylmethane daily. There is insufficient reliable information ava... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in amounts commonly found in foods. The typical diet supplies 2-24 mg of diindolylmethane daily. There is insufficient reliable information ava... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Pharmacist analysis

DIM does have some theoretical drug interactions to be aware of, but they are generally believed to be only mild to moderate in nature.

Potential drug interactions with DIM include drugs in the following classes:

  • Drugs that are metabolized by the liver enzyme CYP1A2: DIM may induce this enzyme, increasing the metabolism of certain drugs.
  • Diuretics: DIM may reduce sodium levels, and could have additive effects with diuretics that increase sodium loss.
  • Estrogen: DIM may have both estrogenic and anti-estrogen effects.

These are all detailed in individual interaction pages.

There is no known interaction between DIM and the drug in question, however.

Nevertheless, always be sure to tell your doctor about all the medications you are taking, supplements included.

—

Still wondering about combining Doxycycline and Diindolylmethane? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Doxycycline

Interactions in our licensed database are recorded against drug classes, not just single drug names. Doxycycline is filed under 9 classifications — including tetracycline antibiotics, antibiotic drugs, p-glycoprotein substrates. Diindolylmethane has documented interactions with 3 drug classes — the most serious being diuretic drugs (moderate), estrogens (moderate) and cytochrome p450 1a2 (cyp1a2) substrates (minor) — and none of Doxycycline’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Diindolylmethane Does Interact With Other Medications

Diindolylmethane has 116 moderate, 153 minor known drug interactions in our database — Doxycycline isn’t one of them. If you take anything else, check it against the full list below.

Moderate 116 Minor 153 No known interaction 2,561 (incl. Doxycycline)
Taking anything else?

Check Another of Your Medications Against Diindolylmethane

Covers the 2,830 medications we’ve checked against Diindolylmethane. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Diindolylmethane and Doxycycline May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Diarrhea / Vomiting / Nausea Additional detail

    Diindolylmethane

    “Orally, diindolylmethane can cause nausea, vomiting, diarrhea, and gas.”

    Diindolylmethane · Natural Medicines adverse-effect record, reported in diarrhea.

    5 sources cited
    1. 47652. Reed, G. A., Arneson, D. W., Putnam, W. C., Smith, H. J., Gray, J. C., Sullivan, D. K., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose and multiple-dose administration of indole-3-carbinol to women: pharmacokinetics based on 3,3'-diindolylmetha
    2. 47676. Reed, G. A., Sunega, J. M., Sullivan, D. K., Gray, J. C., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose pharmacokinetics and tolerability of absorption-enhanced 3,3'-diindolylmethane in healthy subjects. Cancer Epidemiol.Biomarkers Prev. 2008; PubMed
    3. 47709. Del Priore G., Gudipudi, D. K., Montemarano, N., Restivo, A. M., Malanowska-Stega, J., and Arslan, A. A. Oral diindolylmethane (DIM): pilot evaluation of a nonsurgical treatment for cervical dysplasia. Gynecol.Oncol. 2010;116(3):464-467. PubMed
    4. 47729. Heath, E. I., Heilbrun, L. K., Li, J., Vaishampayan, U., Harper, F., Pemberton, P., and Sarkar, F. H. A phase I dose-escalation study of oral BR-DIM (BioResponse 3,3'- Diindolylmethane) in castrate-resistant, non-metastatic prostate cancer. Am.J.Transl.R
    5. 93836. Castañon A, Tristram A, Mesher D, Powell N, Beer H, Ashman S, Rieck G, Fielder H, Fiander A, Sasieni P. Effect of diindolylmethane supplementation on low-grade cervical cytological abnormalities: double-blind, randomised, controlled trial. Br J Cancer. 20 PubMed

    Doxycycline

    Listed in the ADVERSE REACTIONS section of the FDA label for Doxycycline. Read the label on DailyMed ›

  • A skin rash Additional detail

    Diindolylmethane

    “In one case report, a patient developed drug rash with eosinophilia and systemic symptoms (DRESS) after consuming a product containing diindolylmethane, vitamin E, and broccoli powder. The patient developed fever, activated lymphocytes, and swollen lymph nodes. An allergen patch test was positive for diindolylmethane.”

    Diindolylmethane · Natural Medicines adverse-effect record, reported in fever.

    1 source cited
    1. 93840. Le TM, Sanders CJ, van de Corput L, van Erpecum KJ, Röckmann H. Drug rash with eosinophilia and systemic symptoms caused by the dietary supplement diindolylmethane. J Allergy Clin Immunol Pract. 2016 Jan-Feb;4(1):175-6. PubMed

    Doxycycline

    Listed in the ADVERSE REACTIONS section of the FDA label for Doxycycline. Read the label on DailyMed ›

  • Headache Additional detail

    Diindolylmethane

    “Orally, diindolylmethane can cause headache. One case has reported ischemic stroke in a 38-year-old female with a history of a patent foramen ovale (PFO), traumatic subdural hematoma, right partial hemicraniectomy, and use of several supplements, including 200 mg of diindolylmethane daily, vitamin D3, vitamin K2, elderberry, caffeine, and possibly cannabis.”

    Diindolylmethane · Natural Medicines adverse-effect record, reported in cluster headache.

    4 sources cited
    1. 47652. Reed, G. A., Arneson, D. W., Putnam, W. C., Smith, H. J., Gray, J. C., Sullivan, D. K., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose and multiple-dose administration of indole-3-carbinol to women: pharmacokinetics based on 3,3'-diindolylmetha
    2. 47676. Reed, G. A., Sunega, J. M., Sullivan, D. K., Gray, J. C., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose pharmacokinetics and tolerability of absorption-enhanced 3,3'-diindolylmethane in healthy subjects. Cancer Epidemiol.Biomarkers Prev. 2008; PubMed
    3. 93836. Castañon A, Tristram A, Mesher D, Powell N, Beer H, Ashman S, Rieck G, Fielder H, Fiander A, Sasieni P. Effect of diindolylmethane supplementation on low-grade cervical cytological abnormalities: double-blind, randomised, controlled trial. Br J Cancer. 20 PubMed
    4. 112895. Pence ST, Mehta K, Crum-Bailey J. The Serious Side of Supplements: An Ischemic Stroke in a Healthy 38-year-old Female. Mil Med 2022. PubMed

    Doxycycline

    Listed in the ADVERSE REACTIONS section of the FDA label for Doxycycline. Read the label on DailyMed ›

Reported for Diindolylmethane but not commonly for Doxycycline: blood clots, a stroke or mini-stroke, low sodium and fever.

Effects for Doxycycline come from the ADVERSE REACTIONS section of its FDA label; effects for Diindolylmethane come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Diindolylmethane in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in amounts commonly found in foods. The typical diet supplies 2-24 mg of diindolylmethane daily. There is insufficient reliable information available about the safety of diindolylmethane when used in amounts greater than those found in foods during pregnancy and lactation; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

Some Doxycycline Products Have a Food Rule — Diindolylmethane Should Not Break It

At least one FDA label for a product containing Doxycycline says to take it on an empty stomach. Most supplements — Diindolylmethane included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Doxycycline on its own and move Diindolylmethane to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Doxycycline products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

2 DOSAGE AND ADMINISTRATION Take one Doxycycline capsule (40 mg) once daily in the morning on an empty stomach, preferably at least one hour prior to or two hours after meals.

From the Dosage and Administration section of the FDA label we read for Doxycycline — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Diindolylmethane or Doxycycline

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Diindolylmethane or Doxycycline, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Doxycycline

This page covers Diindolylmethane only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Doxycycline page lists 166 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Oleander (major) and Siberian Cocklebur (major).

By severity: 7 major · 139 moderate · 20 minor.

From our pharmacist’s overview on the Doxycycline page

“St. John's wort is the supplement I would flag first for anyone on doxycycline (Vibramycin, Doryx), because it can speed the antibiotic out of the body and leave an infection undertreated.”

Reviewed by 2 · Jul 18, 2026

Open the Doxycycline interaction page

One more smart check

Taking Diindolylmethane as Part of a Dietary Supplement Product? Check It for Interactions

We hold 933 real supplement products containing Diindolylmethane, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Diindolylmethane. Even though Diindolylmethane itself has no known interaction with Doxycycline, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Diindolylmethane and Doxycycline Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Diindolylmethane
Top 25%

#199 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Doxycycline
Top 5%

#41 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Diindolylmethane reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Diindolylmethane and Doxycycline records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Diindolylmethane

What is Diindolylmethane?

Diindolylmethane
  • Estrogen/hormone balance
  • Acne and hormonal skin issues
  • Prostate health support
  • Cancer-risk reduction (unproven)
  • PMS and menopause symptoms
  • General 'detox' support

Diindolylmethane (DIM) is a compound made when your body digests cruciferous vegetables, and it is sold as a supplement mainly for hormone balance and cancer prevention. Although early lab studies look interesting, strong human evidence is lacking for most of these uses. Talk with your pharmacist or doctor before taking DIM, especially if you have a hormone-sensitive condition.

A compound formed from indole-3-carbinol found in cruciferous vegetables (broccoli, cabbage, kale, Brussels sprouts) · Capsules, tablets, softgels (often combined with black pepper extract/BioPerine for absorption)

An interaction check asks whether these two react with each other — it does not ask whether Diindolylmethane is a good idea for someone in your situation. Here is what our Diindolylmethane record says about it on its own.

Diindolylmethane: dosing

There is no official, well-established dose for DIM. Supplement products vary widely in strength, and many add black pepper extract to improve absorption.The safest approach is to follow the directions on the product label and use the lowest amount that seems reasonable.

From our Diindolylmethane monograph — the full record covers uses, side effects and every documented interaction.

Read the full Diindolylmethane monograph & all interactions
Medication

About Doxycycline

What Is Doxycycline Used For?

Brand names: Vibra-Tabs, Vibramycin, Doryx, Monodox, Doxycin, Doxy, Doxylin, Doxy-D, Periostat, Doxycycline Injection, Oracea, Xyrosa

Doxycycline belongs to the tetracycline family of antibiotics. It's prescribed for many types of bacterial infections, including respiratory tract infections, sexually transmitted infections (STIs), tick-borne illnesses like Rocky Mountain spotted fever, and eye infections. It's also used to help prevent malaria and, in some cases, as a helper treatment for severe acne.

In situations where penicillin-type antibiotics can't be used — due to allergy, for example — doxycycline can step in as an alternative. It should only be used for infections that are proven or strongly suspected to be caused by bacteria.

See full Doxycycline drug information
Keep checking

Other Drugs & Diindolylmethane

Browse every other medication we’ve checked against Diindolylmethane — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
116Moderate
153Minor
2,560No known interaction
116 Moderate 153 Minor 2,560 No interaction
Moderate

116 interactions

Showing 60 of 116 moderate interactions — see all 116 on the Diindolylmethane page.

Minor

153 interactions

Showing 60 of 153 minor interactions — see all 153 on the Diindolylmethane page.

No interaction 2,560 drugs checked — show the list

We also checked Diindolylmethane against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,560 medications checked with no known interaction — see the full Diindolylmethane list.

See the full Diindolylmethane interactions page
See every supplement checked against Doxycycline, ranked by severity
Evidence & sources

Diindolylmethane References

The 14 references that drive our Diindolylmethane monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Natl Inst Health, Natl Inst Environmental Health Sci. Indole-3-carbinol. Available at: http://ntp-server.niehs.nih.gov.
  2. Balk JL. Indole-3-carbinol for cancer prevention. Altern Med Alert 2000; 3:105-7.
  3. Riby JE, Chang GHF, Firestone GL, Bjeldanes LF. Ligand-independent activation of estrogen receptor function by 3,3'-diindolylmethane in human breast cancer cells. Biochem Pharmacol 2000;60:167-77. PubMed
  4. Lake BG, Tredger JM, Renwick AB, et al. 3'3-diindolylmethane induces CYP1A2 in cultured precision-cut human liver slices. Xenobiotica 1998;28:803-11. PubMed
  5. Dalessandri, K. M., Firestone, G. L., Fitch, M. D., Bradlow, H. L., and Bjeldanes, L. F. Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer. Nutr Canc PubMed
  6. Reed, G. A., Arneson, D. W., Putnam, W. C., Smith, H. J., Gray, J. C., Sullivan, D. K., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose and multiple-dose administration of indole-3-carbinol to women: pharmacokinetics based on 3,3'-diindolylmetha
  7. Reed, G. A., Sunega, J. M., Sullivan, D. K., Gray, J. C., Mayo, M. S., Crowell, J. A., and Hurwitz, A. Single-dose pharmacokinetics and tolerability of absorption-enhanced 3,3'-diindolylmethane in healthy subjects. Cancer Epidemiol.Biomarkers Prev. 2008; PubMed
  8. Del Priore G., Gudipudi, D. K., Montemarano, N., Restivo, A. M., Malanowska-Stega, J., and Arslan, A. A. Oral diindolylmethane (DIM): pilot evaluation of a nonsurgical treatment for cervical dysplasia. Gynecol.Oncol. 2010;116(3):464-467. PubMed
  9. Heath, E. I., Heilbrun, L. K., Li, J., Vaishampayan, U., Harper, F., Pemberton, P., and Sarkar, F. H. A phase I dose-escalation study of oral BR-DIM (BioResponse 3,3'- Diindolylmethane) in castrate-resistant, non-metastatic prostate cancer. Am.J.Transl.R
  10. Jellinck, P. H., Forkert, P. G., Riddick, D. S., Okey, A. B., Michnovicz, J. J., and Bradlow, H. L. Ah receptor binding properties of indole carbinols and induction of hepatic estradiol hydroxylation. Biochem.Pharmacol. 3-9-1993;45(5):1129-1136. PubMed
  11. Bui PV, Moualla M, Upson DJ. A Possible Association of Diindolylmethane with Pulmonary Embolism and Deep Venous Thrombosis. Case Rep Med. 2016;2016:7527098. PubMed
  12. Castañon A, Tristram A, Mesher D, Powell N, Beer H, Ashman S, Rieck G, Fielder H, Fiander A, Sasieni P. Effect of diindolylmethane supplementation on low-grade cervical cytological abnormalities: double-blind, randomised, controlled trial. Br J Cancer. 20 PubMed
  13. Le TM, Sanders CJ, van de Corput L, van Erpecum KJ, Röckmann H. Drug rash with eosinophilia and systemic symptoms caused by the dietary supplement diindolylmethane. J Allergy Clin Immunol Pract. 2016 Jan-Feb;4(1):175-6. PubMed
  14. Pence ST, Mehta K, Crum-Bailey J. The Serious Side of Supplements: An Ischemic Stroke in a Healthy 38-year-old Female. Mil Med 2022. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Diindolylmethane and Doxycycline Together: Common Questions

Is it safe to take Diindolylmethane with Doxycycline?
We do not list a known interaction between Diindolylmethane and Doxycycline. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Diindolylmethane and Doxycycline have any of the same side effects?
Yes — our sources link each of them separately to 5 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Should I take Diindolylmethane and Doxycycline at the same time of day?
At least one FDA label for a product containing Doxycycline says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Doxycycline on its own and move Diindolylmethane to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Diindolylmethane and Doxycycline combination checked?
Interactions in our licensed database are recorded against drug classes. Doxycycline is filed under 9 classifications, and Diindolylmethane has documented interactions with 3 drug classes — none of Doxycycline's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Diindolylmethane interact with any other medications?
Yes. Diindolylmethane has 269 documented drug interactions in our database — Doxycycline is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Doxycycline interact with any supplements?
Yes. Doxycycline has documented interactions with 166 supplements in our database — Diindolylmethane is not one of them. The Doxycycline interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Diindolylmethane monograph Uses, safety profile, and every drug interaction in one place Doxycycline drug information The full plain-English guide to this medication Doxycycline supplement interactions Every supplement checked against Doxycycline, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 14 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Doxycycline and Diindolylmethane?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.