Interactions on record — worth a quick check against your medications. Based on 3 of 4 ingredients. Check your meds →
Dietary supplement

Ultra I-3-C Ingredients & Drug Interactions

by Douglas Laboratories

Capsule Category: Other Combinations
Most serious interaction: Moderate
The interaction bottom line Most serious interaction: Moderate

Ultra I-3-C is a dietary supplement by Douglas Laboratories with 4 active ingredients. Its ingredients are commonly taken for general nutrition and antioxidant support, heart and digestive health, detoxification support.Based on those ingredients, 295 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Indole-3-Carbinol, standardized Broccoli, standardized Cauliflower. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

HelloPharmacist Scorecard of Ultra I-3-C by Douglas Laboratories

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 1 of its 4 active ingredients.
  • “Proprietary Blend” is a proprietary blend — the label gives one combined amount (100 mg) without saying how much of each component you get.

Ultra I-3-C has 4 ingredients. The active ones are indole-3-carbinol (a compound from cruciferous vegetables), plus standardized extracts of broccoli, cauliflower, and brussel sprout — all from the cabbage family.

These are packaged in inactive ingredients including a vegetable capsule material, microcrystalline cellulose, and vegetable stearate.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded its ingredients' overall clinical evidence instead.

Moderate

Some clinical evidence supports its ingredients for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredients' overall clinical evidence instead.
  • On file: Colorectal cancer — rated "Possibly Effective" (Broccoli) (Natural Medicines).

The evidence for indole-3-carbinol is insufficient to rate it for breast cancer, colorectal cancer, cervical dysplasia, liver disease, or fibromyalgia. Broccoli is possibly effective for colorectal cancer, but evidence is insufficient for bladder cancer, breast cancer, fibromyalgia, and gastric cancer.

Cauliflower's evidence is insufficient for bladder cancer, breast cancer, lung cancer, diabetes, and prostate cancer. In short: the evidence we hold doesn't establish this product's effectiveness for any condition.

The evidence, ingredient by ingredient Broccoli Cauliflower Indole-3-carbinol

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 2 of the 3 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 3 of 3.
  • General safety write-ups exist for 3 of 3.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Indole-3-carbinol is generally well tolerated when taken by mouth, though some people report diarrhea, nausea, rash, tremor, and unsteadiness — the last two can be dose-related (an adult taking 400 mg twice daily developed imbalance and tremor after 10 days; it resolved when the dose was cut in half). Broccoli and cauliflower extracts may cause loose stools, diarrhea, abdominal pain, or cramping, especially at higher doses.

Indole-3-carbinol safety has not been established in pregnancy and is advised against while breastfeeding. Broccoli is likely safe in pregnancy and lactation when eaten as food, though some infants become gassier.

Cauliflower safety data in pregnancy and lactation applies to food amounts; concentrated supplements are not well studied.

Side effects, ingredient by ingredient Broccoli Cauliflower Indole-3-carbinol

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 3 of the 3 matched ingredients can interact with medications — Indole-3-carbinol, Broccoli, Cauliflower.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 295 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check the search tool for blood thinners (anticoagulants and antiplatelet drugs) — indole-3-carbinol may increase bleeding risk. Also check any drugs metabolized by the CYP1A2 enzyme (broccoli and cauliflower can speed their clearance and reduce effectiveness), drugs metabolized by CYP2A6 (broccoli affects this too), and estrogen therapy (indole-3-carbinol may interfere with it).

These are moderate-severity interactions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with some supporting evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

If you take blood thinners, estrogen therapy, or drugs metabolized by CYP1A2 or CYP2A6 enzymes, check your medications with the tool on this page before starting. If you're pregnant or breastfeeding, talk with your pharmacist or doctor first — the safety profile varies by ingredient and dose form.

For everyone else, the main concern is digestive upset at higher doses.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 3 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Aug 23, 2020.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Ultra I-3-C, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539037775
Net contents 60 Vegetarian Capsule(s)
Market status On market
Date entered into DSLD Aug 23, 2020
DSLD ID 232288
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Women (not pregnant or lactating), Adult Female (18 - 50 Years), Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Ultra I-3-C by Douglas Laboratories, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Vegetarian Capsule(s)
Maximum serving Sizes:
1 Vegetarian Capsule(s)
Servings per container
60
UPC/BARCODE
310539037775
IngredientAmount% DV
Proprietary Blend100 mg--
Indole-3-Carbinol200 mg--
standardized Broccoli0 NP--
standardized Cauliflower0 NP--
standardized Brussel Sprout0 NP--

Other ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Vegetable Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults take 1 capsule daily or as directed by your health professional.

Precautions

Warning: Not to be taken by pregnant or lactating women. If you have any health condition or are taking any medication, consult your health professional before use.

Keep out of the reach of children.

Use only if safety seal is intact.

Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity. Scan to learn about our manufacturing excellence

Storage

Store in a cool, dry place.

Formulation

Gluten-free, Non-GMO

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

FDA Statement of Identity

Dietary Supplement

Formula

Support for healthy estrogen balance

See for yourself

Ultra I-3-C by Douglas Laboratories label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

What’s inside

The Ingredients in Ultra I-3-C by Douglas Laboratories

These are the 4 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Vegetarian Capsule(s) Dosage formCapsule Servings per container60 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Proprietary Blend

100 mg per serving

Indole-3-Carbinol

Interacts with
294 drugs
200 mg per serving

Indole-3-carbinol (I3C) is a compound formed when you eat cruciferous vegetables like broccoli and cabbage, and it is sold as a supplement mainly for...

Indole-3-Carbinol monograph & interactions

Other (inactive) ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Vegetable Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Ultra I-3-C by Douglas Laboratories Drug Interactions

Want to check YOUR meds against Ultra I-3-C?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

Go to the checker
295Drugs
295 Moderate

Ingredients driving the most interactions

Each ingredient & the kinds of drugs it affects

For each ingredient in Ultra I-3-C with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Indole-3-Carbinol3 drug types · 294 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, indole-3-carbinol might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.
In vitro research shows that indole-3-carbinol inhibits platelet aggregation.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, indole-3-carbinol might increase the metabolism of CYP1A2 substrates and lower serum concentrations.
Animal research shows that indole-3-carbinol induces CYP1A2 enzymes.

Likelihood Possible Evidence D
Estrogens

Indole-3-carbinol might interfere with the effects of estrogen therapy.
Preliminary clinical and in vitro evidence shows that indole-3-carbinol has antiestrogenic activity.

Likelihood Possible Evidence D

standardized Broccoli2 drug types · 187 drugs

Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, broccoli might reduce the levels and effects of drugs metabolized by CYP1A2.
Pharmacokinetic research in humans shows that eating 500 grams of fresh broccoli daily for 6-12 days can increase CYP1A2 activity by 10% to 200%. Induction of CYP1A2 activity by broccoli is attributed to its glucosinolate constituents.

Likelihood Possible Evidence B
Cytochrome P450 2A6 (Cyp2A6) Substrates

Theoretically, broccoli might reduce the levels and effects of drugs metabolized by CYP2A6.
Pharmacokinetic research in humans shows that eating 500 grams of broccoli daily for 6 days increases CYP2A6 activity by 135% to 550%. Induction of CYP2A6 activity is attributed to its glucosinolate constituents.

Likelihood Possible Evidence B

standardized Cauliflower1 drug type · 186 drugs

Cytochrome P450 1A2 (Cyp1A2) Substrates

Preliminary clinical evidence suggests that eating cruciferous vegetables, including broccoli, cauliflower, daikon radish sprouts, and cabbage, can increase cytochrome P450 1A2 (CYP1A2) activity by 14% to 27%. Theoretically, cauliflower might increase the clearance and decrease the effects of drugs metabolized by CYP1A2. Some drugs metabolized by CYP1A2 include clozapine (Clozaril), cyclobenzaprine (Flexeril), fluvoxamine (Luvox), haloperidol (Haldol), imipramine (Tofranil), mexiletine (Mexitil), olanzapine (Zyprexa), pentazocine (Talwin), propranolol (Inderal), tacrine (Cognex), theophylline, zileuton (Zyflo), zolmitriptan (Zomig), and others.

Likelihood Possible Evidence B
The maker

Brand information

Manufacturer and brand details for Ultra I-3-C, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

Ultra I-3-C by Douglas Laboratories: Common Questions

Does Ultra I-3-C by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, Ultra I-3-C has a known interaction with 295 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Ultra I-3-C contains 4 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Can I take this if I'm pregnant?
Safety data for indole-3-carbinol in pregnancy hasn't been established; the facts advise against concentrated supplements. Broccoli is likely safe when eaten as food during pregnancy, but the safety of concentrated broccoli and cauliflower supplements is less clear. Talk with your doctor or pharmacist for personalized advice.
Can I take this while breastfeeding?
Indole-3-carbinol use is not recommended while breastfeeding due to insufficient safety data. Broccoli is likely safe, and cauliflower is generally safe (though some babies get gassier). Since this product contains indole-3-carbinol, discuss it with your pharmacist or doctor first.
What are the most common side effects?
Indole-3-carbinol is generally well tolerated, but diarrhea, nausea, tremor, and unsteadiness have been reported — unsteadiness and tremor tend to occur at higher doses. Broccoli and cauliflower extracts may cause diarrhea, loose stools, abdominal pain, or cramping, especially at high doses.
Does this actually work for cancer?
The evidence we hold is insufficient to rate indole-3-carbinol for breast, colorectal, or cervical cancers. Broccoli is possibly effective for colorectal cancer, but evidence for other cancers is insufficient. This is not a substitute for medical treatment.
What is indole-3-carbinol?
It's a compound found naturally in cruciferous vegetables like broccoli and cabbage. In this supplement, it's a concentrated extract rather than the food form.
Are there any fillers or other ingredients?
Yes, the capsule contains three inactive ingredients: hydroxypropyl methylcellulose (the capsule material), microcrystalline cellulose, and vegetable stearate.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Ultra I-3-C label
Sources

Sources & How We Checked

Ultra I-3-C's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 23 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Indole-3-carbinol 9 references
  1. Rosen CA, Woodson GE, Thompson JW, et al. Preliminary results of the use of indole-3-carbinol for recurrent respiratory papillomatosis. Otolaryngol Head Neck Surg 1998;118:810-5. PubMed
  2. Bell MC, Crowley-Nowick P, Bradlow HL, et al. Placebo-controlled trial of indole-3-carbinol in the treatment of CIN. Gynecol Oncol 2000;78:123-9. PubMed
  3. He YH, Friesen MD, Ruch RJ, Schut HA. Indole-3-carbinol as a chemopreventive agent in 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) carcinogenesis: inhibition of PhIP-DNA adduct formation, acceleration of PhIP metabolism, and induction of cytoch
  4. Kim, Y. S. and Milner, J. A. Targets for indole-3-carbinol in cancer prevention. J.Nutr.Biochem. 2005;16(2):65-73. PubMed
  5. Anon. Indole-3-carbinol. Monograph. Alternative Medicine Review 2005;10(4):337-42.
  6. McAlindon TE, Gulin J, Chen T, et al. Indole-3-carbinol in women with SLE: effect on estrogen metabolism and disease activity. Lupus 2001;10:779-83. PubMed
  7. Reed GA, Peterson KS, Smith HJ, et al. A phase I study of indole-3-carbinol in women: tolerability and effects. Cancer Epidemiol Biomarkers Prev 2005;14:1953-60. PubMed
  8. 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;3:591-5.
  9. Paliwal P, Chauhan G, Gautam D, Dash D, Patne SCU, Krishnamurthy S. Indole-3-carbinol improves neurobehavioral symptoms in a cerebral ischemic stroke model. Naunyn Schmiedebergs Arch Pharmacol. 2018;391(6):613-625. PubMed

See these in context on the Indole-3-carbinol monograph →

Broccoli 5 references
  1. Kristal AR, Lampe JW. Brassica vegetables and prostate cancer risk: a review of the epidemiological evidence. Nutr Cancer 2002;42:1-9. PubMed
  2. Chakrabarti A, Prais L, Foulds IS. Allergic contact dermatitis to broccoli. Br J Dermatol 2003;148:172-3. PubMed
  3. Hakooz, N. and Hamdan, I. Effects of dietary broccoli on human in vivo caffeine metabolism: a pilot study on a group of Jordanian volunteers. Curr Drug Metab 2007;8(1):9-15. PubMed
  4. Kall MA, Vang O, Clausen J. Effects of dietary broccoli on human drug metabolising activity. Cancer Lett. 1997;114(1-2):169-70. PubMed
  5. Bauman JE, Hsu CH, Centuori S, et al. Randomized Crossover Trial Evaluating Detoxification of Tobacco Carcinogens by Broccoli Seed and Sprout Extract in Current Smokers. Cancers (Basel). 2022;14(9):2129. Published 2022 Apr 24. PubMed

See these in context on the Broccoli monograph →

Cauliflower 9 references
  1. Joshipura KJ, Ascherio A, Manson JE, et al. Fruit and vegetable intake in relation to risk of ischemic stroke. JAMA 1999;282:1233-39. PubMed
  2. Zhao H, Lin J, Grossman HB, et al. Dietary isothiocyanates, GSTM1, GSTT1, NAT2 polymorphisms and bladder cancer risk. Int J Cancer 2007;120:2208-13.
  3. Cohen, J. H., Kristal, A. R., and Stanford, J. L. Fruit and vegetable intakes and prostate cancer risk. J Natl.Cancer Inst. 1-5-2000;92(1):61-68. PubMed
  4. Michaud DS, Spiegelman D, Clinton SK, et al. Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort. J Natl Cancer Inst 1999;91(7):605-13. PubMed
  5. Feskanich D, Ziegler RG, Michaud DS, et al. Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women. J Natl Cancer Inst 2000;92(22):1812-23. PubMed
  6. Chang ET, Smedby KE, Zhang SM, et al. Dietary factors and risk of non-Hodgkin lymphoma in men and women. Cancer Epidemiol Biomarkers Prev 2005;14(2):512-20. PubMed
  7. Liu S, Serdula M, Janket SJ, et al. A prospective study of fruit and vegetable intake and the risk of type 2 diabetes in women. Diabetes Care 2004;27(12):2993-6. PubMed
  8. Gaudet MM, Britton JA, Kabat GC, et al. Fruits, vegetables, and micronutrients in relation to breast cancer modified by menopause and hormone receptor status. Cancer Epidemiol Biomarkers Prev 2004;13(9):1485-94. DOI
  9. Peterson S, Schwarz Y, Li SS, et al. CYP1A2, GSTM1, and GSTT1 polymorphisms and diet effects on CYP1A2 activity in a crossover feeding trial. Cancer Epidemiol Biomarkers Prev 2009;18(11):3118-25.

See these in context on the Cauliflower monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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