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Dietary supplement

Maximum Strength Horny Goat Weed Plus Maca Ingredients & Drug Interactions

by 21st Century

Maximum Strength Horny Goat Weed Plus Maca label
See full label image
Capsule Category: Botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Maximum Strength Horny Goat Weed Plus Maca against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Maximum Strength Horny Goat Weed Plus Maca is a dietary supplement by 21st Century with 2 active ingredients. Its ingredients are commonly taken for low libido and sexual function, energy and stamina, menopause symptoms.Based on those ingredients, 963 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Horny Goat Weed Extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Maximum Strength Horny Goat Weed Plus Maca by 21st Century

Ask about any prescription or over-the-counter medication and we check it for interactions with Maximum Strength Horny Goat Weed Plus Maca by 21st Century — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Maximum Strength Horny Goat Weed Plus Maca by 21st Century

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

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Aug 20, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains 2 active ingredients: maca and horny goat weed extract. Maca is a plant root used traditionally for energy and sexual function, while horny goat weed extract comes from a leafy plant with a similar traditional use.

The capsules also contain inactive ingredients—gelatin, rice bran, oat fiber, magnesium stearate, and silicon dioxide—which serve as the capsule shell and binding agents.

Does it work?

Insufficient 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
Insufficient

There isn't enough reliable clinical evidence to rate this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: support for healthy sexual function.
  • We looked for evidence on: Erectile dysfunction (ED), Sexual desire, Sexual dysfunction, Antidepressant-induced sexual dysfunction, Age-related testosterone deficiency, Male infertility — and 3 related terms.
  • The closest evidence on file: Maca is rated "Insufficient Reliable Evidence To Rate" for Antidepressant-induced sexual dysfunction (Natural Medicines).
  • Also on file: Maca is rated "Insufficient Reliable Evidence To Rate" for Sexual desire, Age-related testosterone deficiency, Male infertility.
  • Also on file: Horny Goat Weed is rated "Insufficient Reliable Evidence To Rate" for Sexual dysfunction, Erectile dysfunction (ED), Male infertility.

The evidence we hold doesn't establish that either ingredient works for its intended purposes. Both maca and horny goat weed have been studied for sexual dysfunction, athletic performance, and other conditions, but the data rates those uses as having insufficient reliable evidence—meaning the studies so far haven't proven benefit convincingly enough to rate them as effective.

If sexual function is what you're after, talk with your doctor or pharmacist about whether the research on this product matches what you're hoping for.

The evidence, ingredient by ingredient Maca Horny Goat Weed

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 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Horny goat weed is generally tolerated when used short-term, though a small number of people report dizziness, dry mouth, nosebleed, thirst, or vomiting. Maca may cause stomach pain if consumed fresh and uncooked, but as a processed supplement it's generally well tolerated as a food.

However, long-term supplement safety hasn't been well studied for either ingredient. The safety data advises against both maca and horny goat weed during pregnancy and breastfeeding—there isn't enough information to know either way with certainty, so talk with your doctor or pharmacist if you're pregnant, planning pregnancy, or nursing.

Side effects, ingredient by ingredient Maca Horny Goat Weed

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?
  • 1 of the 2 matched ingredients can interact with medications — Horny Goat Weed.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 964 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 this product, double-check with your doctor or pharmacist if you take blood thinners or antiplatelet drugs (warfarin, aspirin, clopidogrel), medications that lower blood pressure, estrogen-based therapies (birth control or hormone replacement), or any antidepressant—all carry Moderate interaction risks. Also check if you take any drug metabolized by liver enzymes CYP1A2, CYP2B6, or CYP3A4, as horny goat weed may increase how those drugs work.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with insufficient evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

This product is intended for sexual function and athletic performance, but the current evidence doesn't reliably support either use. More importantly, horny goat weed carries theoretical but unconfirmed risks with blood thinners, certain antidepressants, blood pressure medications, and several other drug classes metabolized by the liver.

If you're on any prescription medication, check your exact drugs against the interaction tool before you start. Talk with your own doctor or pharmacist about whether this product is right for you.

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

Assessment coverage: 2 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2012.

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 Maximum Strength Horny Goat Weed Plus Maca, straight from the product label.

Brand 21st Century
Barcode (UPC) 740985226650
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Jul 25, 2012
DSLD ID 11398
Product type Botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 Maximum Strength Horny Goat Weed Plus Maca by 21st Century, 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:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
30
UPC/BARCODE
740985226650
IngredientAmount% DV
Maca500 mg--
Horny Goat Weed Extract500 mg--

Other ingredients: Gelatin, Rice Bran, Oat Fiber, Magnesium Stearate, Silicon Dioxide

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.
Storage

Store at room temperature.

General Statements

Unconditionally guaranteed for purity, freshness and label potency.

HERBAL EXTRACT

Support For Healthy Sexual Function*

Horny Goat Weed (Epimedium sagitatum) in studies has shown to create a natural libido-lift and support healthy sexual desire in men and women* Maca (Lepidium meyenii) has been used for centuries by native Peruvians as an all natural enhancer for healthy sexual function.* 21st Century's standardized herbal extracts are thoroughly tested to assure specific levels of the important active ingredients are present for maximum benefit.

Maximum Strength

Formulation

No added Sugar, Salt, Yeast, Artificial Flavors, Colors or Preservatives.

FDA Statement of Identity

Dietary Supplement

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.

Brand IP Statement(s)

21ST Century(R)...for a healthier future.

Suggested/Recommended/Usage/Directions

Directions: For enhanced performance take two (2) capsules 60 minutes before needed, or as directed by your healthcare provider. Do not exceed recommended dosage.

Precautions

Keep out of reach of children.

Do not use if product appears to be tampered with or seal is broken.

General

0907

Seals/Symbols

MADE IN USA

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Maximum Strength Horny Goat Weed Plus Maca by 21st Century label

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

Maximum Strength Horny Goat Weed Plus Maca label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Maximum Strength Horny Goat Weed Plus Maca by 21st Century

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container30 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.

Maca

No known
interactions
500 mg per serving

Maca is a nutrient-rich Andean root often used for energy, libido, and menopause symptoms. Early studies suggest it may modestly help sexual desire an...

Maca monograph & interactions

Horny Goat Weed Extract

Interacts with
963 drugs
500 mg per serving Form: Epimedium sagitatum

Horny goat weed (Epimedium) is a traditional Chinese herb most often marketed for low libido and erectile problems, but solid human evidence for these...

Horny Goat Weed Extract monograph & interactions

Other (inactive) ingredients: Gelatin, Rice Bran, Oat Fiber, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Maximum Strength Horny Goat Weed Plus Maca by 21st Century Drug Interactions

Want to check YOUR meds against Maximum Strength Horny Goat Weed Plus Maca?

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
963Drugs
963 Moderate

Ingredients driving the most interactions

Horny Goat Weed Extract 963

Individual Drug Interactions

The ingredients in Maximum Strength Horny Goat Weed Plus Maca interact with 963 drugs. Click any drug to see the details.

1 of the 2 ingredients in Maximum Strength Horny Goat Weed Plus Maca interact with drugs. Each result below shows which ingredient is responsible. Horny Goat Weed Extract

Each ingredient & the kinds of drugs it affects

For each ingredient in Maximum Strength Horny Goat Weed Plus Maca with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Horny Goat Weed Extract6 drug types · 963 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, horny goat weed might increase the risk of bleeding.
In vitro research and animal research shows that horny goat weed can inhibit platelet aggregation and thrombus formation. This effect has not been reported in humans.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, horny goat weed might increase the risk of hypotension.
Laboratory research suggests that horny goat weed might have hypotensive effects. This effect has not been reported in humans.

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

Theoretically, horny goat weed might increase the effects and side effects of CYP1A2 substrates.
In vitro, horny goat weed leaf extract inhibits CYP1A2. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2B6 (Cyp2B6) Substrates

Theoretically, horny goat weed might increase the effects and side effects of CYP2B6 substrates.
In vitro, horny goat weed leaf extract inhibits CYP2B6. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, horny goat weed might increase the effects and side effects of CYP3A4 substrates.
In vitro, horny goat weed extract inhibits CYP3A4 and suppresses CYP3A4 mRNA expression. This effect has not been reported in humans.

Likelihood Possible Evidence D
Estrogens

Theoretically, concomitant use of horny goat weed with estrogens might increase their therapeutic and adverse effects.
In vitro evidence suggests that horny goat weed has estrogenic activity. In clinical research, horny goat weed has been shown to increase blood levels of estrogen in some females.

Likelihood Possible Evidence D
Horny Goat Weed Extract full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Maximum Strength Horny Goat Weed Plus Maca, from the product label.

21st Century

See all 21st Century products
Name
21st Century HealthCare, Inc.
Street Address
2119 S. Wilson Street
City
Tempe
State
AZ
ZipCode
85282
Web Address
www.21stcenturyvitamins.com
Pharmacist Counseling Corner

Maximum Strength Horny Goat Weed Plus Maca by 21st Century: Common Questions

Does Maximum Strength Horny Goat Weed Plus Maca by 21st Century interact with any medications?
Yes. Based on its ingredients, Maximum Strength Horny Goat Weed Plus Maca has a known interaction with 963 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Maximum Strength Horny Goat Weed Plus Maca contains 2 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 while pregnant or breastfeeding?
No. The safety data advises against both maca and horny goat weed during pregnancy and while breastfeeding. Talk with your doctor or pharmacist about what's safe for you if you're pregnant, planning pregnancy, or nursing.
What side effects might I experience?
Horny goat weed most commonly causes dizziness, dry mouth, nosebleed, thirst, or vomiting with short-term use. Maca may cause stomach pain if it's fresh and uncooked. Long-term side effects haven't been well studied for either ingredient.
Does this product actually improve sexual function?
The evidence we hold rates both ingredients as having insufficient reliable evidence for sexual dysfunction—meaning studies haven't yet proven they work for this purpose convincingly. Talk with your doctor about options that have stronger evidence if that's your goal.
What exactly is horny goat weed?
Horny goat weed is a leafy plant traditionally used for sexual function and energy. This product uses an extract of that plant, concentrated for dosing in a capsule.
Why does this product say it might interact with so many medications?
Horny goat weed extract appears to affect liver enzymes that break down hundreds of different drugs, so it could theoretically increase the effects of any medication using those pathways. These risks haven't been confirmed in actual patients, but that's why it's important to check your specific drugs before starting.

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

Not sure if Maximum Strength Horny Goat Weed Plus Maca is safe with your meds?

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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.

Maximum Strength Horny Goat Weed Plus Maca label
Go deeper

The Full Monographs Behind Maximum Strength Horny Goat Weed Plus Maca’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Maca

Maca is a nutrient-rich Andean root often used for energy, libido, and menopause symptoms. Early studies suggest it may modestly help sexual desire and some menopause symptoms, but the evide...

Read the full Maca monograph → Herb & supplement monograph

Horny Goat Weed

Interacts with 963 drugs

Horny goat weed (Epimedium) is a traditional Chinese herb most often marketed for low libido and erectile problems, but solid human evidence for these uses is lacking. While short-term use s...

Read the full Horny Goat Weed monograph →
Sources

Sources & How We Checked

Maximum Strength Horny Goat Weed Plus Maca'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 12 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.

Maca 1 reference
  1. Valerio, L. G., Jr. and Gonzales, G. F. Toxicological aspects of the South American herbs cat's claw (Uncaria tomentosa) and Maca (Lepidium meyenii) : a critical synopsis. Toxicol.Rev 2005;24(1):11-35. PubMed

See these in context on the Maca monograph →

Horny Goat Weed 11 references
  1. Cirigliano MD, Szapary PO. Horny goat weed for erectile dysfunction. Alt Med Alert 2001;4:19-22.
  2. Partin JF, Pushkin YR. Tachyarrhythmia and hypomania with horny goat weed. Psychosomatics 2004;45:536-7. PubMed
  3. De Naeyer A, Pocock V, Milligan S, De Keukeleire D. Estrogenic activity of a polyphenolic extract of the leaves of Epimedium brevicornum. Fitoterapia 2005;76:35-40. PubMed
  4. Zhang CZ, Wang SX, Zhang Y, et al. In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol 2005;98:295-300. PubMed
  5. Yap SP, Shen P, Li J, et al. Molecular and pharmacodynamic properties of estrogenic extracts from the traditional Chinese medicinal herb, Epimedium. J Ethnopharmacol 2007;113:218-24. PubMed
  6. Yan, F. F., Liu, Y., Liu, Y. F., and Zhao, Y. X. Herba Epimedii water extract elevates estrogen level and improves lipid metabolism in postmenopausal women. Phytother.Res. 2008;22(9):1224-1228. PubMed
  7. Ramanathan VS, Mitropoulos E, Shlopov B, et al. An Enzyte'ing' case of acute hepatitis. J Clin Gastroenterol 2011;45(9):834-5. PubMed
  8. Zhong Q, Shi Z, Zhang L, et al. The potential of Epimedium koreanum Nakai for herb-drug interaction. J Pharm Pharmacol 2017;69(10):1398-408. doi: 10.1111/jphp.12773.
  9. Irfan M, Kwon TH, Lee DH, et al. Antiplatelet and Antithrombotic Effects of Epimedium koreanum Nakai. Evid Based Complement Alternat Med. Apr 2021;2021:7071987. PubMed
  10. Tan K, Yang W, Pang L, Hou F. Differences in clinical characteristics among 726 patients with Chinese herbal medicine- or Western medicine-induced liver injury. Medicine (Baltimore) 2022;101(32):e29909. PubMed
  11. Li K, Yu XH, Maskey AR, et al. Cytochrome P450 3A4 suppression by epimedium and active compound kaempferol leads to synergistic anti-inflammatory effect with corticosteroid. Front Pharmacol 2023;13:1042756. PubMed

See these in context on the Horny Goat Weed 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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