Product Reviews and Information for Chronic Bronchitis
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Product Review
NAC (N-Acetyl Cysteine) Supplements Review
Choose the Best NAC Supplement and Save Money
Clinical Update
12/04/2017
What NAC (N-Acetylcysteine)
NAC is both a supplement and a drug used to treat conditions ranging from flu and chronic bronchitis to compulsive behavior. A recent study evaluated its use in preventing kidney injury during angiography (imaging of blood vessels). Get the results and learn more in the "What It Does" section of the NAC (N-Acetylcysteine) Supplements Review >> Also see our top choices among NAC supplements.
Product Review
Echinacea Supplements Review
Many Echinacea Supplements Fail CL's Tests. Make Sure You Know What You're Getting!
Product Review
Prostate Supplements Review (Saw Palmetto and Beta-Sitosterol)
Find the Best Prostate Supplement for Symptoms of BPH. See Which Prostate Supplement Passed or Failed CL's Tests of Quality.
CL Answer
Is it true that NAC can help clear nasal passages?
Find out if N-Acetyl Cysteine (NAC) can help with post nasal drip & general sinus congestion and about supplements that may reduce cold symptoms.
CL Answer
Mullein Tea: Possible Health Effects and Safety
Mullein tea is often promoted for relieving symptoms of lung conditions, including coughing, hoarseness, sore throat, and shortness of breath. Find out if there is evidence to support these uses, and learn about possible side effects of mullein.
CL Answer
What is the difference between cysteine and cystine?
Find out the difference between cysteine and cystine amino acids, including where each is found and their functions.
CL Answer
Do any supplements help prevent or treat a cold?
Are there supplements that can help prevent or treat cold symptoms? Learn more about zinc, probiotics, vitamin C and more.
CL Answer
Are people with kidney disease at risk of getting too much potassium if they take a multivitamin? Which multivitamins are best for people with kidney disease?
Learn if people with kidney disease are at increased risk of getting too much potassium from multivitamins, find out which multivitamins do not contain potassium, and learn what other products should be avoided by people restricting potassium intake.
CL Answer
Will pregnenolone help slow down aging or reduce chronic pain?
Learn more about the steroid hormone pregnenolone, including its effects in the body and on aging and chronic pain.
CL Answer
Do any supplements help with pancreatitis? Do any cause pancreatitis?
Find out if supplements including digestive enzymes, antioxidants, or medium-chain triglycerides are beneficial for chronic pancreatitis, and learn which supplements might worsen symptoms.
News Release
April 15, 2026
Think Expensive NAC Is Better? ConsumerLab Tests Say Otherwise
White Plains, NY, April 15, 2026 — NAC (N-acetyl cysteine) supplements are widely marketed for “detoxification,” immune support, and respiratory health, as NAC is converted in the body into the antioxidant glutathione.
CL Answer
Can vitamins or other supplements cause a change in the ability to taste, or even a loss of taste?
Find out if supplements or vitamin deficiencies can cause changes in taste, loss of taste or smell. Information about vitamin D, zinc, vitamins A, B6, B12 and others. Plus medications and medical conditions that can alter taste and smell. ConsumerLab.com's answer explains.
CL Answer
Which supplements and foods help relieve constipation and which can cause constipation?
Find out which supplements can cause constipation, including iron, calcium, protein powders and drinks and others. ConsumerLab.com's answer explains.
CL Answer
Do any supplements help for varicose veins or chronic venous insufficiency?
Find out which supplements help for varicose veins and chronic venous insufficiency, including citrus bioflavonoids and grape seed extract.
CL Answer
Supplements For Back Pain: What Helps, What's Hype
Some supplements may provide modest benefit for back pain, while others don't seem to work or haven't been evaluated for this use. Find out if supplements like collagen, devil's claw, PEA, pregnenolone, white willow bark, and others help.
News Release
September 26, 2024
What’s Really In Shilajit Supplements? ConsumerLab Tests Reveal Amounts of Fulvic Acid & Heavy Metals
White Plains, NY, September 26, 2024 -- Shilajit is a tar-like substance created by decomposed plant material and found in mountain rocks.
News Release
March 11, 2019
Best NAC (N-acetyl cysteine) Supplements Identified by ConsumerLab
White Plains, New York, March 11, 2019 — NAC (N-acetyl cysteine) supplements are promoted for many uses, including "liver support," "immune support," and reducing symptoms of the flu and flare-ups of chronic bronchitis.
CL Answer
Are antioxidant supplements good or bad for you?
Learn more about whether antioxidants like astaxanthin, beta-carotene, coenzyme Q10, curcumin, resveratrol, selenium, vitamin A, vitamin C and vitamin E are safe and if they help prevent chronic diseases.
Clinical Update
10/28/2024
Supplements for Varicose Veins
Do any supplements reduce the appearance of varicose veins or improve the symptoms of chronic venous insufficiency? Find out in our updated article about supplements for varicose veins and chronic venous insufficiency.
Clinical Update
1/11/2022
Ginkgo and Cistanche for Chronic Fatigue Syndrome?
Does supplementing with ginkgo and cistanche extracts help reduce symptoms of chronic fatigue syndrome? See what a recent study showed in our updated answer to the question: Which supplements help to improve energy and decrease fatigue?
Clinical Update
2/08/2020
Vitamin D for Hives
If you suffer from chronic hives (or chronic urticaria) and are deficient in vitamin D, taking vitamin D may be helpful, according to a new study. (Vitamin D may also be helpful for other skin conditions such as eczema and psoriasis.) Get the details in the What It Does section of the Vitamin D Supplements Review. Also see our Top Picks for vitamin D.
Clinical Update
9/18/2020
Vitamin D for Failing Hearts?
Does high-dose vitamin D help or hurt people with chronic heart failure? Find out what a new study showed in the Cardiovascular Disease section of Vitamin D Supplements Review, which also discusses cholesterol, blood pressure and heart attack risk. Also see our Top Picks for vitamin D.
Clinical Update
10/30/2021
Pycnogenol vs. Other Pine Bark Extracts
There is some evidence that pine bark extract may help improve circulation and chronic venous insufficiency, but be aware that some supplements are not like those used in most clinical trials. Find out what to look on labels in our updated answer to the question: What is Pycnogenol and does it work?
Clinical Update
11/11/2021
Multivitamins and Kidney Disease
People with chronic kidney disease are often advised to limit their intake of an ingredient that, they may not realize, is common in multivitamins. Learn more in the ConsumerTips section of the Multivitamin and Multimineral Supplements Review.
Clinical Update
10/24/2015
Probiotic Helps with Constipation
A recent study found that taking a particular probiotic twice a day after meals significantly increased the number of bowel movements in people with chronic constipation. For details about the probiotic and dose, see the Probiotic Supplements Review >>
Clinical Update
3/15/2017
Anti-Inflammatory Effect of Juice Plus+?
Chronic systemic inflammation is a risk factor for cardiovascular disease, diabetes, and cancer. A recent clinical trial assessed the product Juice Plus+ for its ability to reduce this inflammation in obese men and women. The abstract of the published study indicates that it works, but the results tell a different story. For details, see the "What It Does" section of the Greens and Whole Foods Powders, Pills, and Drinks Review (which includes our tests of products) >>
Clinical Update
12/03/2014
Vitamin D for COPD
A study of people with chronic obstructive pulmonary disease (COPD) found that taking vitamin D significantly reduced the risk of moderate to severe exacerbation, but only among people who began the study deficient in vitamin D. Get the details and information about other uses of vitamin D, along with our quality ratings of vitamin D supplements, in the Vitamin D Supplements Review >>
Clinical Update
6/18/2019
Fish Oil for Heart Failure?
Can taking fish oil improve heart function in people with chronic heart failure? See the results of a recent study (and find out what type of fish oil was used) in the What It Does section of the Fish Oil Supplements Review. Also see our Top Picks for fish oils.
Clinical Update
12/05/2017
Fish Oil for Stress?
A recent study investigated whether taking fish oil rich in the omega-3 fatty acid EPA would reduce chronic stress. See the results in the "What It Does" section of the Fish Oil Supplements Review >>
Clinical Update
4/05/2016
Vitamin D Improves Heart Output
A recent study in people with chronic heart failure (poor heart output) found that vitamin D improved heart output. However, the study did not achieve its main objective — to increase walking distance. The dose may have been to blame. For details see the "What It Does" section of the Vitamin D Supplements Review >>
Clinical Update
11/16/2019
Supplement for Pain?
A recent study gave a modest daily dose of CBD to people with chronic pain who were taking opioid medication to see if it reduced their pain and need for medication. See the results in the What It Does section of the Review. Also see our Top Picks among products.
Clinical Update
2/21/2024
Lumbrokinase for Cancer, Infection?
Can lumbrokinase help slow cancer progression or treat chronic infections such as Lyme disease? Find out in our article about lumbrokinase.
Clinical Update
5/31/2024
Have Kidney Disease? Watch What’s In Your Water
People with chronic kidney disease are particularly susceptible to the toxic effects of heavy metals. Even low levels of lead in drinking water may be harmful, according to a recent study. See our Water Filter Pitchers Review for details. Also see our Top Picks among water filter pitchers.
Clinical Update
9/29/2023
Supplements for Pancreatitis?
Can digestive enzyme supplements work as well as prescription enzymes for chronic pancreatitis, and can any other supplements help? Find out, plus, learn if any supplements can cause pancreatitis, in our new article about supplements and pancreatitis.
Clinical Update
10/10/2023
Constipation & Supplements
Find out which supplements medical experts recommend for chronic versus occasional constipation. See the Laxative use section of our Psyllium Supplements Review, which includes our Top Pick among products.
Also see: Which supplements and foods help relieve constipation and which can cause constipation?
Clinical Update
11/07/2024
Vein Health: Does Butcher's Broom Help?
Does butcher’s broom reduce varicose veins or related symptoms? Find out in our updated article about supplements for varicose veins and chronic venous insufficiency (CVI).
Clinical Update
11/27/2024
B-12 Deficiency & GI Symptoms
Vitamin B-12 deficiency can cause many symptoms, including chronic diarrhea, as described in a recent report. Learn about symptoms of B-12 deficiency in our B Vitamin Supplements Review, which includes our Top Picks for B-12.
Clinical Update
10/28/2024
Triphala for Constipation?
Can Triphala, an Ayurvedic blend of fruits from three plants, help relieve chronic constipation and is it safe? Find out in our article: Which supplements and foods help relieve constipation and which can cause constipation?
Clinical Update
4/17/2025
Supplements for Varicose Veins?
Are any supplements recommended for varicose veins by vascular experts? Find out in our article about supplements for varicose veins or chronic venous insufficiency.
Clinical Update
4/24/2025
Microplastics Linked with High BP, Stroke
Exposure to higher amounts of microplastic was associated with increased risk of several chronic diseases, according to a recent study. Get the details in article about Microplastics in water, salt, foods, and beverages. Also see our Water Filter Pitchers Review for our Top Pick for removing microplastics.
Clinical Update
5/08/2025
Supplements for Hemorrhoids
Do supplements such as Pycnogenol, butcher’s broom, or aescin (found in horse chestnut), help people with hemorrhoids? Find out in our article: Do any supplements help for varicose veins or chronic venous insufficiency?
Clinical Update
10/16/2025
Constipation Solutions: What Works. What Doesn’t
Experts have weighed in on the best remedies for chronic constipation. Find out which foods and supplements made the cut:
Clinical Update
7/26/2022
Vitamin D and Heart Failure
Does high-dose vitamin D improve heart function in people with chronic heart failure? Find out what a recent study showed in the Cardiovascular disease, blood pressure, and cholesterol section of our Vitamin D Supplements Review.
Clinical Update
9/16/2022
Gluten & Dry Eye?
A CL member commented that their chronic dry eye went away after eliminating gluten from their diet. Is there clinical evidence that this can help? Find out in our article about supplements and lifestyle modifications for dry eye.
Clinical Update
12/06/2022
Digestive Enzymes – Prescription vs. Supplements
A CL member with chronic pancreatitis asked about alternatives to costly prescription enzymes. See our Digestive Enzyme Supplements Review for information about prescription enzymes as well as supplements similar to prescription products.
Clinical Update
12/09/2022
Allulose Questions
- Is allulose (a low-calorie sweetener) likely to form compounds that have been linked with chronic disease?
- How can I avoid allulose made from genetically modified corn?
Clinical Update
2/10/2023
Magnesium and Artery Calcification
Did magnesium supplementation slow coronary artery calcification in people with chronic kidney disease? See what a recent study found in the What It Does section of our Magnesium Supplements Review, which includes our Top Picks for magnesium.
Also see: Which supplements or foods can help lower cholesterol and keep my heart healthy? Are there any to avoid?
Clinical Update
5/19/2023
Caution With Sweeteners
Certain sweeteners should not be used for decreasing weight or preventing chronic diseases, according to a new report. Find out which sweeteners are of concern and why in our updated article about sweeteners.
Clinical Update
5/31/2023
Best Fiber Supplement for Constipation?
Which type of fiber supplement is best for treating mild, chronic constipation? See what experts recommend, and why, in the What It Does section of our Psyllium Supplements Review.
Clinical Update
11/13/2025
Supplement for Spider Veins?
Does taking diosmin, a citrus bioflavonoid, reduce spider veins? Find out what a recent study showed in our article about supplements for chronic venous insufficiency.
Clinical Update
11/20/2025
Glucomannan for Constipation?
Did taking glucomannan (a prebiotic fiber) improve symptoms in people with chronic constipation? Find out what a recent study showed in our Prebiotic Supplements Review, which includes our Top Picks for prebiotics.
Clinical Update
4/06/2026
Krill Oil for Back, Hip, and Knee Pain?
Can krill oil ease chronic muscle and joint pain in older people? See what a new study found in our Fish Oil Supplements Review, which includes our Top Picks for fish oil and krill oil.
Recalls & Warnings
December 08, 2017
Limbrel Capsules for Osteoarthritis Linked With Potentially Life-Threatening Health Risk, FDA Warns
On December 4, 2017, the FDA urged consumers not to take Limbrel (Primus Pharmaceuticals), a capsule marketed to manage the metabolic processes associated with osteoarthritis, because it has been associated with serious adverse events, including drug-induced liver injury and a lung ...
News Release
December 09, 2014
Round-up of Recent Product Tests by ConsumerLab.com -- Results for B Vitamin Supplements & Energy Drinks, Garlic, NAC (N-acetyl cysteine), Iron and Omega-7 Fatty Acids
White Plains, New York, December 9, 2014 — In recent months, ConsumerLab.com has published test results for a variety of popular supplements, including B vitamins supplements and energy drinks, NAC (N-acetyl cysteine), iron and garlic. In addition, ConsumerLab.
Recalls & Warnings
March 31, 2005
FDA Warns Marketer of "Vitamin O" Product to Cease Unsubstantiated Claims
The U.S. Food and Drug Adminstration (FDA) has sent a Warning Letter (dated February 8, 2005) to Donald L. Smyth, President, R-Garden Inc., and Rose Creek Health Products, Inc. warning that its "Vitamin O" product was, among other things, being marketed with unsubstantiated health claims.
Recalls & Warnings
December 14, 2023
Pain Relief Tea Recalled, Found to Contain Prescription Drugs
On December 13, 2023, WS Global issued a recall of all lots of the company’s Himalayan Pain Relief Tea after products were found to contain diclofenac and dexamethasone, prescription drugs that are not listed on the product’s label.
Recalls & Warnings
October 21, 2014
Seller of Weight Loss, Saw Palmetto Supplements and More Warned for Drug Claims
On October 9, 2014, the FDA issued a warning letter to Bethel Nutritional Consulting, Inc., following a review of the company's website which found statements made about 15 Day Detox Diet, Alpha Lipoic Acid. 300 mg.
Recalls & Warnings
April 02, 2021
FDA Warns Sellers of Prostate, Reishi, Immune Products, and More
On March 16, 2021, the FDA issued warning letters to two companies following reviews of their websites which found statements made about the companies' products to be drug claims.
Recalls & Warnings
November 07, 2015
Seller of "NaturalDoctor" Vitamin C, Echinacea and More Warned for Manufacturing Violations
On October 16, 2015, the FDA issued a warning letter Sound Healing Arts, PC, dba Grounds for Tea, LLC, following a facility inspection which found the company's products, including NaturalDoctor Vitamins C & K3, NaturalDoctor Goldenseal & Echinacea Plus, NaturalDoctor Centella ...
Recalls & Warnings
May 03, 2013
Maker of Omega-3, Saw Palmetto, St. John’s Wort Supplements And More Warned For Manufacturing Violations and Drug Claims
On March 19, 2013, the FDA issued a warning letter to Sunset Natural Products Inc.
Recalls & Warnings
December 17, 2020
FTC Crackdown on Six Deceptive CBD Products
On December 17, 2020, the FTC announced that it is taking action against six companies for selling CBD products with unsupported and deceptive health claims that they can treat a variety of conditions, including cancer, heart disease, hypertension, Alzheimer's disease, and others.
Recalls & Warnings
May 30, 2020
FTC Sends Refund Checks for TrueAloe and AloeCran
On May 26, 2020, the FTC announced it is mailing 22,581 checks totaling more than $470,000 to consumers who purchased deceptively marketed supplements, TrueAloe and AloeCran.
Recalls & Warnings
October 18, 2017
FDA Warns Seller of Arthritis, Blood Pressure, Diabetes Supplements For Making Drug Claims
On August 15, 2017, the FDA issued a warning letter to Years to Your Health, Inc., following an inspection of the company's website which found a number of their products to be misbranded, as they contained drug claims.
Recalls & Warnings
September 14, 2016
Seller of Aloe, Prostate and Joint Supplements Warned for Manufacturing Violations
On April 8, 2016, the FDA issued a warning letter to Salud Natural Entrepreneurs, Inc.
Recalls & Warnings
May 03, 2013
Homeopathic Company Warned For Drug Claims and Improper Labeling
On March 12, 2013, the FDA issued a warning letter to Natural Medicine Associates, Inc.
Recalls & Warnings
July 11, 2014
Maker of Cough and Sleep "Remedies" Warned for Drug Claims
On June 27, 2014, the FDA issued a warning letter to Zarbee's, Inc.
Recalls & Warnings
May 06, 2014
Seller of Flaxseed, Ginkgo and More Warned for Manufacturing Violations and Drug Claims
On April 18, 2014, the FDA issued a warning letter to Iowa Select Herbs, LLC, following a facility inspection which found the company's products, including Flax Seed, Holy Basil, Papaya Leaf Extract, and Ginkgo Leaf Extract products, to be adulterated because they were prepared, packed, or held ...
Recalls & Warnings
April 17, 2020
Seller of Vitamin D, MSM, Selenium & More Warned for Drug Claims
On March 31, 2020, the FDA issued a warning letter to KetoKerri LLC following a review of the company's website, which found statements made about some of the company's products, including Dr.
Recalls & Warnings
December 22, 2005
Health Canada Warns Consumers Not to Take Chaparral
On December 21, 2005, Health Canada (Canada's health ministry) warned consumers not to ingest the herb chaparral in the form of loose leaves, teas, capsules or bulk herbal products because of the risk of liver and kidney problems.
Recalls & Warnings
August 30, 2012
Supplement Company Warned For Medical Claims and Misbranding Of Omega-3, CoQ10, Noni Juice And More
On July 12, 2012, the FDA issued a warning letter to Alfa Vitamins Laboratories, Inc.
Recalls & Warnings
November 28, 2014
Seller of Herbal Extracts Warned for Manufacturing Violations, Drug Claims
On November 3, 2014, the FDA issued a warning letter to Avena Botanicals, Inc.
Recalls & Warnings
April 02, 2019
FDA Issues Strong Warnings to Sellers of CBD
On March 28, 2019, the FDA issued warning letters to three companies for making unsubstantiated claims about the health benefits of CBD (cannabidiol) products on their websites.
Recalls & Warnings
March 19, 2019
FDA Calls Promotion of Nyloxin Homeopathic Products for Pain a "Health Fraud Scam"
On March 11, 2019, the FDA issued a warning letter to Nutra Pharma Corp. following a review of the company's website (www.Nyloxin.com) and social media sites found that the company was making drug claims about its homeopathic products promoted for arthritis and cancer pain.
Recalls & Warnings
September 10, 2014
Seller of Joint Pain Supplement Warned for Drug Claims
On August 24, 2014, the FDA issued a warning letter to CreAgri, Inc., following a website review, which found statements made about the company's products, including Olivenol plus Easeflex, Olivenol plus Essence Capsules, and Olivenol plus Essence Elixer, to be drug claims.
Recalls & Warnings
September 13, 2013
Metagenics Warned For Misbranding of Medical Foods and Drug Claims
On August 13, 2013, the FDA issued a warning letter to Metagenics, Inc.
Recalls & Warnings
March 16, 2006
Garden of Life, Maker of Primal Defense, Settles FTC Charges
On March 9, 2006, The Federal Trade Commission (FTC) announced that an operation that marketed dietary supplements sold at Whole Foods Market, GNC, the Vitamin Shoppe, and on the Internet settled FTC charges that they made deceptive advertising claims about their supplements.
Recalls & Warnings
June 11, 2015
FDA Warns Maker of Fruit Energy Drinks for Drug Claims
On May 19, 2015, the FDA issued a warning letter to CK Management, Inc. following a facility inspection which found statements made on product labels and websites about Whole5, Fruit of the Spirit and ViaViente "whole food" fruit puree energy drinks to be drug claims.
Recalls & Warnings
July 15, 2014
Vita Springs Health Warned for Manufacturing Violations and Drug Claims
On June 24, 2014, the FDA issued a warning letter to Albert Max Inc.
