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Dietary supplement

L-Cystine Ingredients & Drug Interactions

by BulkSupplements.com

L-Cystine label
See full label image
Powder Category: Amino Acid/protein
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 30, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Cystine 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

L-Cystine is a dietary supplement by BulkSupplements.com with 1 active ingredient. Its ingredients are commonly taken for antioxidant support, skin and hair health, liver support.Based on those ingredients, 86 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Cysteine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against L-Cystine by BulkSupplements.com

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Cystine by BulkSupplements.com — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of L-Cystine by BulkSupplements.com

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 Oct 1, 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 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

L-Cystine contains one active ingredient: L-cysteine, an amino acid your body uses in protein and other metabolic pathways. There are no inactive ingredients in this powder.

Does it work?

Couldn't assess
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
Not assessable

This is a single-ingredient L-cysteine product and its label doesn't state a use — see L-cysteine's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The evidence we hold does not establish how well L-cysteine works for any of the purposes it's marketed toward — including hair loss, leg ulcers, hangover relief, stroke, or stomach inflammation. In each case, the rating is insufficient reliable evidence, meaning the data to confirm a benefit simply isn't there yet.

The evidence, ingredient by ingredient L-cysteine

How safe is it?

Some data gaps
Safety Information · database check
Some gaps

Safety data exists for these ingredients, but with some important gaps.

Why this rating?
  • We hold adverse-effect (side-effect) data for 0 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-cysteine is generally well tolerated at the amounts naturally found in food. However, safety data for high-dose supplements over time is limited, so the long-term safety of taking it as a standalone supplement isn't well studied.

If you're considering it, talk with your doctor or pharmacist first. During pregnancy and lactation, L-cysteine is rated likely safe — but confirm this applies to your situation with your own healthcare provider, especially if you have a reason you're considering supplementation.

Side effects, ingredient by ingredient L-cysteine

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 1 matched ingredient can interact with medications — L-cysteine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: diabetes medications.
  • For scale: 86 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.

If you take any medication to manage blood sugar — insulin, metformin, sulfonylureas, or other antidiabetes drugs — double-check it before starting L-Cystine. There's a Moderate risk that L-cysteine could lower your blood sugar further and raise the chance of hypoglycemia.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and some safety-information gaps remain.

L-Cystine is a single-ingredient amino acid supplement with limited evidence for its stated benefits and sparse long-term safety data at supplement doses. If you take diabetes medication, check it against our interaction tool first.

Talk with your doctor or pharmacist about whether this product makes sense for your needs.

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

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2024.

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 L-Cystine, straight from the product label.

Brand BulkSupplements.com
Barcode (UPC) X001KUI9EJ
Net contents 1 Kilogram(s); 35.3 Ounce(s)
Market status On market
Date entered into DSLD Jul 25, 2024
DSLD ID 312134
Product type Amino Acid/protein
Supplement form Powder
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Dairy 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 L-Cystine by BulkSupplements.com, 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:
500 mg
Maximum serving Sizes:
500 mg
Servings per container
2000
UPC/BARCODE
X001KUI9EJ
IngredientAmount% DV
L-Cysteine500 mg--

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.
Brand IP Statement(s)

BulkSupplements.com Clean & pure bulk supplements

Formulation

Free of: Added sugar, soy, dairy, yeast, gluten, additives

Suggested/Recommended/Usage/Directions

Suggested use: As a dietary supplement, take 500 mg (about 1/5 tsp) one to three times daily, or as directed by a physician.

General Statements

Use an accurate milligram scale.

New

Storage

Contents are sold by weight, not volume. Settling may occur. Store in a dry, cool place

FDA Disclaimer Statement

Warning: This product is not intended to diagnose, treat, cure, or prevent any disease.

Precautions

Always consult a physician before taking any dietary supplement.

Keep out of reach of children.

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

See for yourself

L-Cystine by BulkSupplements.com label

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

L-Cystine 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 L-Cystine by BulkSupplements.com

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size500 mg Dosage formPowder Servings per container2000 Amounts shown are per serving.

L-Cysteine

Interacts with
86 drugs
500 mg per serving

L-cysteine is a sulfur-containing amino acid your body uses to make proteins and the antioxidant glutathione. Most people get enough from food, and su...

L-Cysteine monograph & interactions
Interaction report

L-Cystine by BulkSupplements.com Drug Interactions

Want to check YOUR meds against L-Cystine?

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
86Drugs
86 Moderate

Ingredients driving the most interactions

L-Cysteine 86

Individual Drug Interactions

The ingredients in L-Cystine interact with 86 drugs. Click any drug to see the details.

1 of the 1 ingredient in L-Cystine interact with drugs. Each result below shows which ingredient is responsible. L-Cysteine

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Cystine 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.

L-Cysteine1 drug type · 86 drugs

Antidiabetes Drugs

Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research suggests that L-cysteine can have hypoglycemic effects.

Likelihood Possible Evidence D
L-Cysteine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Cystine, from the product label.

BulkSupplements.com

See all BulkSupplements.com products
Name
BulkSupplements.com
Street Address
7511 Eastgate Rd
City
Henderson
State
NV
ZipCode
89011
Web Address
BulkSupplements.com
Pharmacist Counseling Corner

L-Cystine by BulkSupplements.com: Common Questions

Does L-Cystine by BulkSupplements.com interact with any medications?
Yes. Based on its ingredients, L-Cystine has a known interaction with 86 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Cystine contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
Does L-Cystine actually help with hair loss?
The data we hold shows insufficient evidence to say whether it works for androgenic alopecia (male- or female-pattern hair loss). That doesn't mean it doesn't help — it means the research backing that claim isn't established in the sources we have.
Is L-Cystine safe to take long-term?
Safety data for high-dose L-cysteine supplements over extended periods is limited. At the amounts you'd eat in food, it's well tolerated, but we don't have strong evidence on the long-term safety of taking it as a standalone supplement, so talk with your doctor or pharmacist before using it regularly.
Can I take this while pregnant or breastfeeding?
L-cysteine is rated likely safe during pregnancy and lactation. That said, always confirm with your own doctor or pharmacist that supplementation makes sense for your situation.
What is L-cysteine, and what does my body do with it?
L-cysteine is an amino acid — a building block of protein. Your body uses it to make proteins and for other metabolic functions, and small amounts come from the foods you eat.
Why does the label say 'L-Cystine' but the ingredient is 'L-cysteine'?
L-cystine is the oxidized form of two L-cysteine molecules linked together; when you digest L-cystine, your body converts it back to L-cysteine. They're essentially the same thing in terms of how your body uses it.

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

Not sure if L-Cystine is safe with your meds?

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Ask a pharmacist

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.

L-Cystine label
Go deeper

The Full Monographs Behind L-Cystine’s Ingredients

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

Herb & supplement monograph

L-cysteine

Interacts with 86 drugs

L-cysteine is a sulfur-containing amino acid your body uses to make proteins and the antioxidant glutathione. Most people get enough from food, and supplements are usually well tolerated, bu...

Read the full L-cysteine monograph →
Sources

Sources & How We Checked

L-Cystine'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 2 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.

L-cysteine 2 references
  1. Dowlati Y, Maheux M, Meyer JH. The effect of oral L-cysteine on breast milk and plasma cysteine concentrations. Neuropsychiatr Dis Treat 2020;16:3163-3172.
  2. Lee S, Han KH, Nakamura Y, et al. Dietary L-cysteine improves the antioxidative potential and lipid metabolism in rats fed a normal diet. Biosci Biotechnol Biochem 2013;77(7):1430-4.

See these in context on the L-cysteine 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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