L-Histidine 500 mg Ingredients & Drug Interactions
What is this page for?
First and foremost: checking L-Histidine 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
L-Histidine 500 mg is a dietary supplement by Douglas Laboratories with 1 active ingredient. Its ingredients are commonly taken for skin conditions like eczema, anemia related to kidney disease, allergy and inflammation support.We don’t currently list a known drug interaction for its mapped ingredients — but that doesn’t guarantee none exist, so always confirm with your pharmacist.
HelloPharmacist Scorecard of L-Histidine 500 mg 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.
What’s inside
Full disclosure
This product contains one active ingredient: L-histidine (as L-histidine hydrochloride), an amino acid your body naturally uses in protein synthesis, immune function, and other processes. You get histidine from food—poultry, meat, fish, nuts, and seeds are all sources—so this capsule is a concentrated supplement form of something already in your diet.
The inactive ingredients are microcrystalline cellulose (a bulking agent), gelatin (the capsule material), and ascorbyl palmitate (a form of vitamin C used as a preservative).
Does it work?
Moderate evidence
The evidence for L-histidine supplements is limited. There's some data suggesting it may be possibly effective for cholera, but for other conditions we've looked into—eczema (atopic dermatitis), kidney failure, and rheumatoid arthritis—the evidence isn't strong enough to rate it either way.
Bottom line: we don't have reliable evidence that this supplement works for those conditions, and you shouldn't count on it as a treatment without talking it over with your doctor first.
How safe is it?
Some data gaps
L-histidine from food is considered safe and is part of normal nutrition. At supplement doses, though, the safety profile hasn't been well studied.
The data we hold advises caution with these higher doses unless your doctor has recommended them specifically. No adverse effects were documented in the trials we reviewed.
During pregnancy and lactation, L-histidine is rated as likely safe. That's based on the fact that it's a dietary amino acid, but if you're pregnant or breastfeeding and considering a supplement dose, check in with your doctor or midwife to make sure it's right for you.
Meds to double-check
No known interactions
No interactions are documented in our data for this ingredient. That doesn't mean none exist—it means we haven't found evidence of them.
Before you start, give your doctor or pharmacist your full medication and supplement list so they can check from their side.
The bottom line
Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. No medication interactions are currently documented, and some safety-information gaps remain.
L-Histidine 500 mg might appeal to someone whose doctor has suggested it for a specific reason, or to anyone looking to add an amino acid that's already part of normal food. The evidence for treating disease isn't strong, so don't use it as a stand-in for proven treatments.
Talk with your doctor or pharmacist about whether it makes sense for you.
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 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
General information
Key facts about L-Histidine 500 mg, straight from the product label.
| Brand | Douglas Laboratories |
|---|---|
| Barcode (UPC) | 310539004210 |
| Net contents | 60 Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Aug 23, 2020 |
| DSLD ID | 232444 |
| Product type | Amino Acid/protein |
| Supplement form | Capsule |
| Dietary claims / uses | All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years), Gluten Free |
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-Histidine 500 mg by Douglas Laboratories, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Histidine Hydrochloride | 500 mg | -- |
Other ingredients: Microcrystalline Cellulose, Gelatin, Ascorbyl Palmitate
Tap any ingredient to jump to its full detail below.
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: If you are pregnant, nursing, have any health condition or taking any medication, consult your health professional before using this product.
Keep out of the reach of children.
Use only if safety seal is intact.
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.
General Statements
Scan to learn about our manufacturing excellence Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity.
FDA Statement of Identity
Dietary Supplement
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Histidine 500 mg by Douglas Laboratories label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in L-Histidine 500 mg by Douglas Laboratories
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Capsule(s) Dosage formCapsule Servings per container60 Amounts shown are per serving.
L-Histidine Hydrochloride
No knowninteractions
Histidine is an essential amino acid your body needs to build proteins and to make compounds like histamine and carnosine. Most people get enough from...
L-Histidine Hydrochloride monograph & interactionsOther (inactive) ingredients: Microcrystalline Cellulose, Gelatin, Ascorbyl Palmitate. These complete the product’s ingredient list but are not active constituents.
L-Histidine 500 mg by Douglas Laboratories Drug Interactions
We don’t currently list any known drug interactions for the mapped ingredients in L-Histidine 500 mg. This doesn’t guarantee none exist — always confirm with your pharmacist before combining a supplement with your medications.
Brand information
Manufacturer and brand details for L-Histidine 500 mg, 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
L-Histidine 500 mg by Douglas Laboratories: Common Questions
Does L-Histidine 500 mg by Douglas Laboratories interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Is L-histidine safe during pregnancy or breastfeeding?
Will this help my eczema or rheumatoid arthritis?
What's the difference between L-histidine in food and this supplement?
Are there any side effects I should watch for?
What is L-histidine and why would someone take it?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Histidine 500 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
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.
The Full Monographs Behind L-Histidine 500 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
L-Histidine 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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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 3 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.
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