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Dietary supplement

L-Cysteine 500 mg Ingredients & Drug Interactions

by Solaray

L-Cysteine 500 mg label
See full label image
Capsule Category: Amino Acid/protein
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Cysteine 500 mg 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-Cysteine 500 mg is a dietary supplement by Solaray 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-Cysteine 500 mg by Solaray

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Cysteine 500 mg by Solaray — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of L-Cysteine 500 mg by Solaray

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 Jul 11, 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.

This product contains one active ingredient: L-Cysteine 500 mg per capsule. L-Cysteine is an amino acid your body uses to make proteins and other compounds, including glutathione, which is involved in your cells' antioxidant defenses.

The capsule also contains inactive ingredients — rice concentrate, cellulose, and a rice extract blend — which are fillers and binders that hold the product together.

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 for L-Cysteine doesn't support its use for any of the conditions it's been studied for — hair loss, leg ulcers, hangover, stroke, and gastritis all show insufficient reliable evidence to rate. That doesn't mean it doesn't work; it means the research we have isn't strong enough to say one way or the other.

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 in the amounts you'd get from food, but the safety of high-dose supplements over time hasn't been well studied. Because of that gap in the research, caution is advised with supplement-level doses unless your doctor has advised you to take them.

During pregnancy and lactation, L-Cysteine is rated likely safe based on available data.

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 antidiabetes drugs (insulin or oral medications for blood sugar control), check your specific medications below before starting L-Cysteine — there's a Moderate-severity risk of low blood sugar when the two are combined.

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.

If you're interested in L-Cysteine for hair loss, wound healing, or another reason, know that the evidence for it isn't established yet. If you take antidiabetes medications — insulin or pills — you should check your exact drugs with the tool on this page before you start, since L-Cysteine may lower blood sugar.

Talk with your pharmacist or doctor about whether this supplement fits your situation.

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 Aug 22, 2025.

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-Cysteine 500 mg, straight from the product label.

Brand Solaray
Barcode (UPC) 076280049107
Net contents 30 VegCap(s)
Market status On market
Date entered into DSLD Aug 22, 2025
DSLD ID 338447
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses Nutrient, 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 L-Cysteine 500 mg by Solaray, 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 VegCap(s)
Maximum serving Sizes:
1 VegCap(s)
Servings per container
30
UPC/BARCODE
076280049107
IngredientAmount% DV
L-Cysteine500 mg--

Other ingredients: whole Rice concentrate, Cellulose, Rice extract Blend

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)

Solaray Est. 1973 A brighter way 1973

Formulation

Digestion

FDA Statement of Identity

Dietary Supplement

Seals/Symbols

Lab verified

General Statements

Since 1973, we've scoured the globe for the highest quality ingredients, connecting you with the most efficacious supplements that help you live brighter & embrace the moments that matter most.

100% PCR bottles

Precautions

Warning: Do not use if safety seal is broken or missing. Keep your licensed health care practitioner informed when using this product.

Keep out of reach of children.

Suggested/Recommended/Usage/Directions

Directions: Use only as directed. Take 1 vegcap with a meal or glass of water.

Storage

Store in a cool, dry place.

Formula

Discussion: L-Cysteine is referred to as a semi-essential amino acid. The body produces small amounts of L-Cysteine, but supplementing with added L-Cysteine has many potential benefits. L-Cysteine is a protein building block that helps proteins hold their shape. L-Cysteine, along with the amino acids L-Glutamine and L-Glycine are used by the body to form Glutathione, the "Master Antioxidant." Aside from its use in Glutathione formation, L-Cysteine also helps provide nutritive support for digestion, hair, skin and nails.

FDA Disclaimer Statement

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.

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

See for yourself

L-Cysteine 500 mg by Solaray label

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

L-Cysteine 500 mg 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-Cysteine 500 mg by Solaray

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

Serving size1 VegCap(s) Dosage formCapsule Servings per container30 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

Other (inactive) ingredients: Whole Rice concentrate, Cellulose, Rice extract Blend. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Cysteine 500 mg by Solaray Drug Interactions

Want to check YOUR meds against L-Cysteine 500 mg?

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-Cysteine 500 mg interact with 86 drugs. Click any drug to see the details.

1 of the 1 ingredient in L-Cysteine 500 mg 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-Cysteine 500 mg 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-Cysteine 500 mg, from the product label.

Solaray

See all Solaray products
Name
Nutraceutical Corp.
Web Address
www.nutraceutical.com
Pharmacist Counseling Corner

L-Cysteine 500 mg by Solaray: Common Questions

Does L-Cysteine 500 mg by Solaray interact with any medications?
Yes. Based on its ingredients, L-Cysteine 500 mg 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-Cysteine 500 mg 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-Cysteine actually help with hair loss?
The evidence isn't strong enough to say. Studies have looked at it for androgenic alopecia, but the data we have rates as insufficient reliable evidence, so we can't confirm it works.
Is L-Cysteine safe to take long-term?
At the amounts found in food, yes — it's generally well tolerated. But high-dose supplements haven't been studied enough over time, so caution is advised unless your doctor has told you to take it.
Can I take this while pregnant or breastfeeding?
L-Cysteine is rated likely safe during pregnancy and lactation based on available data. That said, it's always smart to run any supplement by your doctor or pharmacist during pregnancy or while nursing.
What is L-Cysteine and what does it do in my body?
L-Cysteine is an amino acid — a building block of protein — that your body uses to make other important compounds, including glutathione, which helps protect your cells from damage.
Will this help my hangover?
The evidence for L-Cysteine and hangover relief doesn't meet the bar to say it works. Studies have looked at it, but the data rates as insufficient reliable evidence.

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

Not sure if L-Cysteine 500 mg is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

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-Cysteine 500 mg label
Go deeper

The Full Monographs Behind L-Cysteine 500 mg’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-Cysteine 500 mg'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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