Top 5 Problem Dietary Supplements


When natural doesn't always mean safe, and reading labels doesn't necessarily protect consumers.

Interest in and the consumption of dietary supplements in the United States has never been greater, according to the 18th annual CRN Consumer Survey on Dietary Supplements. Nearly nine in 10 adults surveyed said they were confident in the overall safety, quality, and effectiveness of supplements, and three quarters perceived the dietary supplement industry as trustworthy.

What they may not realize is that the supplements they consume on a daily basis can be risky business. Their active ingredients can have serious and unwanted biological effects on the human body, especially when combined with medications and other supplements. Perhaps more importantly, supplements are essentially unregulated by the federal government-so, buyer beware!

Community pharmacists have an important role to play when it comes to dietary supplements. They can help their customers safely choose vitamins, minerals, herbs, and enzymes tailored to their individual needs and their medical and prescription history.

Pharmacists can advise customers about some of the dangers associated with certain supplements, such as the five presented here. All have been linked to serious medical complications when misused or ingested in combination with prescription and over-the-counter medications. Some of these might be uncommon, and others you probably don’t even stock in your pharmacy. But are you taking the time to ask patients what supplements they’re taking?

Up next: Banned by the FDA, but still a problem.



Ma Huang

Also known as ephedra, ma huang is a natural source of ephedrine, pseudoephedrine, and norephedrine. The Chinese botanical is a stimulant that is sold in this country as an appetite suppressant/weight loss aid and athletic performance enhancer. It is also sometimes marketed as a recreational drug "herbal ecstasy."

The FDA banned dietary supplements containing ephedra in 2004, but the ban does not apply to traditional Chinese medicine (TCM) remedies. Since the agency is not authorized to evaluate the safety, effectiveness, or purity of dietary supplements, there are no regulated manufacturing standards in place for them, including ma huang. Consumers must rely on manufacturers and distributors to make sure that the products are safe.  

Ma huang has been linked to serious, even fatal health complications including: irregular heartbeats, heart attack, stroke, and sudden death. Other reported side effects are increased blood pressure, agitation, hostility, personality changes, suicidal thoughts, pain or difficulty passing urine, and rapid or troubled breathing.



Pure Powdered Caffeine

Caffeine is practically a staple of the American diet, devoured by consumers of all ages in coffee, tea, and energy and soft drinks. But powdered caffeine products are far more concentrated and dangerous than caffeinated beverages.

According to the FDA, there is a very fine line between a safe amount and a toxic dose of pure powdered caffeine. A standard teaspoon delivers the caffeine equivalent of about 28 cups of regular coffee, but a teaspoon is far too imprecise a tool for calculating the number of milligrams of caffeine in a serving size. This can result in accidental overdoses.

In 2015, the FDA issued warning letters to five powdered caffeine distributors that their products present a significant or unreasonable risk of illness or injury. Users may suffer from elevated or dangerously erratic heartbeat, high blood pressure, seizures, and even death. Other side effects of caffeine toxicity include diarrhea, vomiting, stupor, and disorientation. The effects of caffeine can be heightened by pre-existing conditions, making the product even more dangerous.


Red Yeast Rice

This traditional Chinese culinary and medicinal product is marketed in the U.S. to lower cholesterol and related lipids. A 2017 study of red yeast rice products revealed a wide range of monacolin K, a compound that is chemically identical to the active ingredient in lovastatin. Products containing higher levels could lower cholesterol levels and cause the same types of side effects and drug interactions as lovastatin. Researchers found that other products had little to no monacolin K. In all cases, no information about the amount of monacolin K was listed on the product labels.

The FDA maintains that red yeast rice products containing more than trace amounts of monacolin K are unapproved new drugs and cannot be sold legally as ̢۬dietary supplements.

Side effects related to red yeast rice include myopathy, rhabdomyolysis, and liver toxicity. Some products have been found to be contaminated during processing with citrinin, a mycotoxin that has caused kidney failure in experimental animals and genetic damage in human cells.


St. John’s wort

St. John’s wort(Hypericum perforatum) is a flowering weed that has been used for centuries for mental health conditions and is widely prescribed for depression in Europe. There are also claims that this herbal stimulant is effective for smoking cessation and treating anxiety, sleep disorders, irritable bowel syndrome, hot flashes, and premenstrual syndrome. Modern day studies, however, have yielded mixed results for its efficacy.

What is proven is that St. John’s wort weakens the effectiveness of many prescription medications. The list includes antidepressants, birth control pills, cyclosporine, digoxin, warfarin, oxycodone, and some HIV and cancer drugs.

Symptoms associated with the use of St. John’s wort include agitation, diarrhea, rapid heartbeat, high blood pressure, hallucinations, sexual dysfunction, fatigue, dizziness, confusion, and a rise in body temperature. It has also been linked to a worsening of psychotic symptoms in people with bipolar disorder or schizophrenia.



Native to western Africa, the yohimbe is an evergreen tree whose bark contains the alkaloid yohimbine that is touted as a treatment for impotence and an athletic performance enhancer. It is also used to counteract the sexual side effects of certain antidepressants. (Man-made yohimbine hydrochloride is available in the U.S. as a prescription drug for erectile dysfunction; it cannot be sold legally as a dietary supplement.)

Most yohimbe product labels don’t indicate how much yohimbine they contain. The amount and type (synthetic or highly processed plant extract) differs considerably among products, according to recent studies. This makes it difficult for users to know how much yohimbine they are ingesting, leading to potentially serious consequences.

Taken in high dosages, yohimbe can cause difficulty in breathing, paralysis, very low blood pressure, heart attack, seizures, and death. Side effects of a typical dose include stomach problems, excitation, tremor, irritability, sleep problems, anxiety or agitation, and dizziness.


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