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Dietary supplement

L-W Ingredients & Drug Interactions

by Pure Herbs

Liquid Category: Botanical
Most serious interaction: Moderate
The interaction bottom line Most serious interaction: Moderate

L-W is a dietary supplement by Pure Herbs with 6 active ingredients. Its ingredients are commonly taken for cough and chest congestion, sore throat, bronchitis and respiratory irritation.Based on those ingredients, 2,044 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Marshmallow Root Extract, Gentian Root Extract, Mullein Leaf Extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

HelloPharmacist Scorecard of L-W by Pure Herbs

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 0 of its 6 active ingredients.
  • “Proprietary Blend” is a proprietary blend — the label gives one combined amount (1,865 mg) without saying how much of each component you get.

Pure Herbs L-W is a liquid herbal blend with six active ingredients. Mullein leaf extract is included for respiratory support; marshmallow root extract and lobelia aerial parts extract contribute traditional herbal elements; gentian root extract supports digestive function; blessed thistle aerial parts extract aids digestion and traditionally supports milk supply; and yerba santa leaf extract rounds out the formula.

The product contains no inactive fillers or other ingredients—just the six herbal extracts.

Does it work?

Not established
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 established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use.

Why this rating?
  • The label markets this product for: respiratory system health and lung function.
  • We looked for evidence on: Asthma, Bronchitis, Cough, Respiratory tract infections, chest congestion, bronchial irritation — and 1 related terms.
  • The closest evidence on file: Mullein is rated "Insufficient Reliable Evidence To Rate" for Bronchitis (Natural Medicines).
  • Also on file: Mullein is rated "Insufficient Reliable Evidence To Rate" for Asthma, Cough.
  • Also on file: Marshmallow is rated "Insufficient Reliable Evidence To Rate" for ACE inhibitor-induced cough, Respiratory tract infections.

The evidence for these ingredients is limited. Mullein leaf, marshmallow root, gentian root, and yerba santa leaf all lack reliable evidence for the conditions they've been studied for—the data we hold rates them as having insufficient evidence.

Blessed thistle's effectiveness for digestive upset (dyspepsia) is also unproven by the standards we use. Lobelia, by contrast, is rated possibly ineffective for smoking cessation.

If you're considering this product to address a specific health concern, talk it over with your doctor or pharmacist about whether the evidence supports its use for your situation.

The evidence, ingredient by ingredient Mullein Marshmallow Lobelia Gentian Blessed Thistle Yerba Santa

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 4 of the 6 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 6 of 6.
  • General safety write-ups exist for 6 of 6.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Several of these herbs are generally well tolerated for short-term use, but human safety data are limited overall. Lobelia warrants special caution: it can cause serious effects at higher doses, with reported symptoms including nausea, vomiting, diarrhea, tremors, dizziness, and throat irritation.

At doses of 600 mg or higher, lobelia can cause toxicity with rapid heartbeat, very low blood pressure, and potentially fatal effects. Blessed thistle in very high doses (more than 5 grams per cup of tea) may cause stomach irritation and vomiting.

Gentian may upset the stomach, and all five of these herbs lack sufficient safety data in pregnancy. Mullein leaf and marshmallow root are best avoided during pregnancy; lobelia is rated likely unsafe in pregnancy.

For breastfeeding, mullein, marshmallow, lobelia, and yerba santa all lack safety data and should be avoided. Blessed thistle has been used traditionally to support milk supply, but safety hasn't been well studied—check with your doctor or pharmacist before using it while nursing.

Side effects, ingredient by ingredient Mullein Marshmallow Lobelia Gentian Blessed Thistle Yerba Santa

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?
  • 6 of the 6 matched ingredients can interact with medications — Blessed Thistle, Lobelia, Yerba Santa, Mullein, Gentian, among others.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; lithium.
  • For scale: 2,045 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 Pure Herbs L-W, double-check with your doctor or pharmacist if you take lithium (three of its ingredients may raise lithium levels dangerously); blood pressure medications (gentian may lower your pressure further); blood thinners or antiplatelet drugs like aspirin or warfarin (mullein and marshmallow may thin blood further); or acid-reducing medications including H2-blockers, antacids, or proton pump inhibitors (blessed thistle may counteract them).

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with no established evidence rating for its marketed use. Moderate medication interactions have been identified, and safety information is well characterized.

L-W is a traditional herbal blend best suited to adults with no lithium use, uncontrolled blood pressure, active bleeding disorders, or stomach acid medications on board. If you take any prescription medication at all, especially for lithium levels, blood pressure, clotting, or digestion, check your specific drugs on this page before starting.

Pregnant and breastfeeding people should avoid it unless their own doctor advises otherwise. Talk with your pharmacist or doctor about whether this product fits your health picture.

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

Assessment coverage: 6 of 6 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 23, 2023.

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-W, straight from the product label.

Brand Pure Herbs
Net contents 4 Fluid Ounce(s); 120 mL
Market status On market
Date entered into DSLD Jan 23, 2023
DSLD ID 281356
Product type Botanical
Supplement form Liquid
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Women (not pregnant or lactating)
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-W by Pure Herbs, 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 mL
Maximum serving Sizes:
2 mL
Servings per container
60
IngredientAmount% DV
Proprietary Blend1865 mg--
Mullein Leaf Extract0 NP--
Marshmallow Root Extract0 NP--
Lobelia Aerial Parts Extract0 NP--
Gentian Root Extract0 NP--
Blessed Thistle Aerial Parts Extract0 NP--
Yerba Santa leaf extract0 NP--

Other ingredients: None

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

Directions: For adults, mix 2 mL (abt. 1/2 tsp) of extract in 2 fl. oz (60 mL) water one time daily preferably with a meal.

Shake well before use

Formulation

Helps to maintain a healthy respiratory system. Supports healthy lung function.

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.

Precautions

Warning: Not intended for use by pregnant or nursing women. If you have a medical condition or are taking medication, consult your doctor prior to use.

Discontinue use and consult with your doctor if any adverse reactions occur.

Keep out of reach of children

Brand IP Statement(s)

Pure Herbs, Ltd. Natural Herbal Extracts

FDA Statement of Identity

Dietary Supplement

General Statements

"No expense has been spared to provide the finest nature has to offer."

See for yourself

L-W by Pure Herbs label

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

What’s inside

The Ingredients in L-W by Pure Herbs

These are the 6 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 mL Dosage formLiquid 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.

Other (inactive) ingredients: None. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-W by Pure Herbs Drug Interactions

Want to check YOUR meds against L-W?

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
2,044Drugs
173 Moderate 1,871 Minor

Each ingredient & the kinds of drugs it affects

For each ingredient in L-W 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.

Marshmallow Root Extract3 drug types · 2,040 drugs

Lithium

Theoretically, due to potential diuretic effects, marshmallow might reduce excretion and increase levels of lithium.
Marshmallow is thought to have diuretic properties. To avoid lithium toxicity, the dose of lithium might need to be decreased when used with marshmallow.

Likelihood Probable Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, marshmallow flower might have antiplatelet effects.
Animal research suggests that marshmallow flower extract has antiplatelet effects. However, the root and leaf of marshmallow, not the flower, are the plant parts most commonly found in dietary supplements. Theoretically, use of marshmallow flower with anticoagulant/antiplatelet drugs can have additive effects, and might increase the risk for bleeding in some patients.

Likelihood Unlikely Evidence D
Oral Drugs

Theoretically, mucilage in marshmallow might impair absorption of oral drugs.
Marshmallow contains mucilage which can affect oral drug absorption. To avoid changes in absorption, take marshmallow 30-60 minutes after oral medications.

Likelihood Possible Evidence D

Gentian Root Extract1 drug type · 172 drugs

Antihypertensive Drugs

Theoretically, taking gentian with antihypertensive drugs might increase the risk of hypotension.
In vitro research shows that gentian can cause vasodilation and lower blood pressure.

Likelihood Possible Evidence D

Mullein Leaf Extract1 drug type · 122 drugs

Anticoagulant/Antiplatelet Drugs

Lab tests on extracts from different parts of common and dense-flowered mullein plants show that they do have some blood-thinning effects, as they increase the time it takes for blood to clot. This is likely due to at least one of the known constituents of muellein, triterpenoid saponins. However, the effects appear to be mild and results have been inconsistent. Extracts from different plant parts have been show to have varying anticoagulant strengths, with water-based ones being more potent than alcohol-based extracts.

Likelihood Unlikely Evidence A

Blessed Thistle Aerial Parts Extract3 drug types · 36 drugs

Antacids

Theoretically, blessed thistle might decrease the effectiveness of antacids.
There are reports that blessed thistle increases stomach acid.

Likelihood Possible Evidence D
H2-Blockers

Theoretically, blessed thistle might decrease the effectiveness of H2-blockers.
There are reports that blessed thistle increases stomach acid.

Likelihood Possible Evidence D
Proton Pump Inhibitors (Ppis)

Theoretically, blessed thistle might decrease the effectiveness of PPIs.
There are reports that blessed thistle increases stomach acid.

Likelihood Possible Evidence D

Lobelia Aerial Parts Extract1 drug type · 1 drug

Lithium

Lobelia is thought to have diuretic properties. Theoretically, due to these potential diuretic effects, lobelia might reduce excretion and increase levels of lithium. The dose of lithium might need to be decreased.

Likelihood Probable Evidence D

Yerba Santa leaf extract1 drug type · 1 drug

Lithium

Yerba santa is thought to have diuretic properties. Theoretically, due to these potential diuretic effects, yerba santa might reduce excretion and increase levels of lithium. The dose of lithium might need to be decreased.

Likelihood Probable Evidence D
The maker

Brand information

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

Pure Herbs

See all Pure Herbs products
Name
Pure Herbs, Ltd.
City
Sterling Heights
State
MI
Phone Number
(800) 860-4372
Web Address
www.pureherbs.com
Pharmacist Counseling Corner

L-W by Pure Herbs: Common Questions

Does L-W by Pure Herbs interact with any medications?
Yes. Based on its ingredients, L-W has a known interaction with 2,044 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-W contains 6 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 L-W while I'm pregnant?
No—mullein leaf and marshmallow root should be avoided during pregnancy due to insufficient safety data, and lobelia is rated likely unsafe in pregnancy. The other ingredients also lack adequate safety information. Talk with your doctor or pharmacist about whether this product is right for you during pregnancy.
Is it safe to take L-W while breastfeeding?
Most of the ingredients in L-W are not well studied in nursing mothers. Mullein, marshmallow, lobelia, and yerba santa should be avoided while breastfeeding. Blessed thistle has been used traditionally to support milk supply, but safety hasn't been established—check with your doctor or pharmacist first.
What does this blend actually do?
The evidence for these herbs is limited. We don't have reliable proof that mullein, marshmallow, gentian, blessed thistle, or yerba santa work for the conditions they're traditionally used for, and lobelia is considered possibly ineffective for smoking cessation. If you're taking it for a specific reason, ask your pharmacist whether the current evidence supports that use.
What's lobelia in this product for, and is it safe?
Lobelia aerial parts are included as a traditional herbal ingredient, but it can cause serious side effects at higher doses—nausea, vomiting, tremors, dizziness, and throat irritation have been reported, and doses of 600 mg or higher can cause toxicity with rapid heartbeat, dangerous drops in blood pressure, and potentially life-threatening effects. Caution is strongly advised.
What side effects has blessed thistle caused?
In small amounts, blessed thistle is often well tolerated. At very high doses (more than 5 grams per cup of tea), it can cause stomach irritation and vomiting. People sensitive to ragweed or other plants in the daisy family may have an allergic skin reaction to topical blessed thistle.
If I take L-W with my other medications, will it change how they work?
Yes—depending on which medications you take, this blend may interfere with them. Marshmallow can interfere with how your body absorbs oral drugs if taken at the same time; blessed thistle may make acid-reducing medications less effective; and several ingredients may affect blood thinners, blood pressure control, and lithium levels. Check your specific medications on this page, then talk with your pharmacist or doctor.

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.

L-W label
Go deeper

The Full Monographs Behind L-W’s Ingredients

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

Herb & supplement monograph

Mullein

Interacts with 122 drugs

Mullein is a traditional herbal remedy most often used as a tea or syrup to soothe coughs, sore throats, and respiratory irritation. High-quality human studies are lacking, so its benefits a...

Read the full Mullein monograph →
Herb & supplement monograph

Marshmallow

Interacts with 2,040 drugs

Marshmallow root is a traditional herb rich in soothing, gel-like fibers called mucilage, which is why it has long been used for coughs, sore throats, and stomach irritation. Evidence for th...

Read the full Marshmallow monograph →
Herb & supplement monograph

Lobelia

Interacts with 1 drug

Lobelia is a traditional herb once used for breathing problems and to help people quit smoking, but reliable evidence supporting these uses is lacking. It can be toxic in higher amounts, cau...

Read the full Lobelia monograph →
Herb & supplement monograph

Gentian

Interacts with 172 drugs

Gentian is a very bitter root traditionally used to stimulate appetite and ease mild digestive complaints, often as part of "bitters" before meals. The evidence is mostly traditional and pre...

Read the full Gentian monograph →
Herb & supplement monograph

Blessed Thistle

Interacts with 36 drugs

Blessed thistle is a bitter herb traditionally used to stimulate appetite and ease mild digestive complaints. High-quality human studies are lacking, so its benefits are not well proven. It...

Read the full Blessed Thistle monograph →
Herb & supplement monograph

Yerba Santa

Interacts with 1 drug

Yerba Santa is an aromatic shrub from the western United States and Mexico that has long been used in folk medicine for coughs, congestion, and other respiratory complaints. Modern scientifi...

Read the full Yerba Santa monograph →
Sources

Sources & How We Checked

L-W'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 20 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.

Mullein 2 references
  1. Castro AI, Carmona JB, Gonzales FG, Nestar OB. Occupational airborne dermatitis from gordolobo (Verbascum densiflorum). Contact Dermatitis 2006;55(5):301.
  2. Flores Echaiz C, Al Ali A, Cao AQ, Sasseville D. Simultaneous contact dermatitis caused by Asteraceae and Verbascum thapsus. Contact Dermatitis 2017;76(5):316-8.

See these in context on the Mullein monograph →

Marshmallow 5 references
  1. Monographs on the medicinal uses of plant drugs. Exeter, UK: European Scientific Co-op Phytother, 1997.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  5. Hage-Sleiman R, Mroueh M, Daher CF. Pharmacological evaluation of aqueous extract of Althaea officinalis flower grown in Lebanon. Pharm Biol 2011;49(3):327-33.

See these in context on the Marshmallow monograph →

Lobelia 6 references
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. McChargue DE, Collins FL Jr, Cohen LM. Effect of non-nicotinic moist snuff replacement and lobeline on withdrawal symptoms during 48-h smokeless tobacco deprivation. Nicotine Tob Res 2002;4:195-200. PubMed
  5. Stead LF, Hughes JR. Lobeline for smoking cessation. Cochrane Database Syst Rev 2000;2:CD000124. PubMed
  6. Plakun, A. L., Ambrus, J., Bross, I., Graham, S., Levin, M. L., and Ross, C. A. Clinical factors in smoking withdrawal: preliminary report. Am J Public Health Nations.Health 1966;56(3):434-441. PubMed

See these in context on the Lobelia monograph →

Gentian 5 references
  1. Neubauer N, Marz RW. Placebo-controlled, randomized, double-blind, clincal trial with Sinupret sugar coated tablets on the basis of a therapy with antibiotics and decongestant nasal drops in acute sinusitis. Phytomedicine 1994;1:177-81.
  2. Marz RW, Ismail C, Popp MA. Action profile and efficacy of a herbal combination preparation for the treatment of sinusitis. Wien Med Wochenschr 1999;149:202-8.
  3. Uncini Manganelli RE, Chericoni S, Baragatti B. Ethnopharmacobotany in Tuscany: plants used as antihypertensives. Fitoterapia 2000;71:S95-100. PubMed
  4. Baragatti B, Calderone V, Testai L, et al. Vasodilator activity of crude methanolic extract of Gentiana kokiana Perr. et Song. (Gentianaceae). J Ethnopharmacol 2002;79:369-72. PubMed
  5. Sanatani M, Younus J, Stitt L, et al. Tolerability of the combination of ginger (Zingiber officinalis), gentian (Gentiana lutea) and turmeric (Curcuma longa) in patients with cancer-associated anorexia. J Complement Integr Med. 2015;12(1):57-60.

See these in context on the Gentian monograph →

Blessed Thistle 2 references
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

See these in context on the Blessed Thistle 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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