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 contains four active ingredients: indole-3-carbinol (a compound from cruciferous vegetables), plus standardized extracts of broccoli, cauliflower, and brussel sprout. These are paired with inactive ingredients — hydroxypropyl methylcellulose, microcrystalline cellulose, and vegetable stearate — that serve as a capsule shell and filler.

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 supporting indole-3-carbinol for breast cancer, colorectal cancer, cervical dysplasia, liver disease, and fibromyalgia is not established in our data — each of these areas is rated as having insufficient reliable evidence. Broccoli is rated possibly effective for colorectal cancer, though evidence for other uses (bladder cancer, breast cancer, fibromyalgia, gastric cancer) is insufficient.

For cauliflower and brussel sprout, the evidence we hold does not establish their effectiveness for any condition listed.

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 orally, though diarrhea, nausea, rash, tremor, imbalance, and unsteadiness have been reported — particularly imbalance and tremor at higher doses (an adult taking 400 mg twice daily experienced these symptoms within 10 days). Broccoli as a food is safe for most people, but concentrated supplements in this product are less studied; loose stools, diarrhea, abdominal pain, and cramping have been reported, especially at high doses.

Cauliflower as food is generally safe, but the concentrated extract form is not well studied. Safety data for indole-3-carbinol in pregnancy advises against supplement use, and breastfeeding use is not recommended — there isn't enough data to know it's safe.

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.

Before taking Ultra I-3-C, have your own doctor or pharmacist review any blood thinners (anticoagulants) or antiplatelet drugs you take — indole-3-carbinol may increase bleeding risk (Moderate severity). Also check CYP1A2 and CYP2A6 substrate drugs; broccoli and cauliflower may reduce their effectiveness (Moderate severity).

If you take estrogen therapy, confirm this product won't interfere with it.

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.

This product combines three cruciferous extracts that may affect how your liver processes certain medications, particularly those cleared by CYP1A2 and CYP2A6 enzymes, and may increase bleeding risk with blood thinners. If you take any prescription medications, estrogen therapy, or blood thinners, check with your own doctor or pharmacist before starting.

The product is generally well tolerated, but gastrointestinal side effects and imbalance can occur, especially 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 or breastfeeding?
The safety data advises against indole-3-carbinol supplements in pregnancy due to possible hormone effects and insufficient study, and breastfeeding use is not recommended. Broccoli and cauliflower as foods are generally fine in pregnancy, but this product contains concentrated extracts, and the safety of that form in pregnancy and nursing isn't well established. Talk with your doctor or pharmacist for personalized advice.
Does this product actually work for cancer prevention?
Broccoli is rated possibly effective for colorectal cancer, but evidence for indole-3-carbinol and the other ingredients — for breast, colorectal, cervical, bladder, gastric, and lung cancers — is not established in our data. None of these products should replace medical screening or treatment.
What are the most common side effects?
Diarrhea and loose stools are the most frequently reported, especially with concentrated extracts at higher doses. Nausea, rash, and imbalance or tremor have also been reported, particularly when doses are high.
Why does this product have so many drug interactions?
Broccoli and cauliflower contain glucosinolates that rev up liver enzymes (CYP1A2 and CYP2A6), which clear hundreds of medications. Even eating fresh broccoli can increase these enzymes by 10% to 550%; concentrated supplements may have a larger effect. This means dozens of common drugs could be cleared faster and become less effective.
Is this product safe to take long-term?
Long-term safety data isn't robust in our sources. Because concentrated cruciferous extracts are less studied than the food forms, and because some people report tremor or imbalance especially at higher doses, discuss long-term use with your doctor or pharmacist before committing.

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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