Potential Dangers of Herbal Drug Interactions

What you should know about alternative medications

For centuries, humans have relied on botanicals and herbal remedies for the relief of aches, pains, and ailments. Humans trusted herbal remedies to provide them with a natural means of relief, due to the accessibility and affordability of the world’s most popular herbal medicines. In fact, despite technological advances in modern medicine, the demand for herbals has grown into a thriving business, with an industry that grosses ~$60 billion per annum.2

The industry has proved to be resilient during months of lockdown, when consumers found themselves shopping for natural remedies that might boost wellness and/or support immune health during a global pandemic. Yet consumers new to the herbal industry found they knew little about possible drug interactions with prescription medications, or where to find support for their questions. Neither did their neighbors or all their healthcare providers, who might have questions about common herbs available via the internet or OTC. 

It can be a dangerous endeavor, as a colleague learned when taking St. John’s Wort without discussing the dose or the idea with his physician. One Friday evening (and one beer) later, he entered the Emergency Room with new onset atrial fibrillation. Luckily for him, rehydration and eventual elimination of the herbal remedy converted him back to normal sinus rhythm.

The implications

When studying the use of botanicals, a list of the most frequently used herbal medications yields several agents, from St. John’s Wort to Ginseng, and Chamomile to Elderberry. Unfortunately, when cross-referencing the same herbals against a list of potentially dangerous chemicals, several appear on both lists. These agents, although they have been around for centuries, are not benign. This should be a warning to consumers who choose to self-medicate without investigating what they are taking. The botanicals may interact with prescription therapies or exacerbate conditions they might be attempting to ease.2

Unlike prescription medications, herbal therapies have not undergone controlled research trials in humans and may not have studies regarding dosage levels that could prove toxic. Use in pregnancy and/or in breastfeeding mothers is discouraged. Problems that could occur when taking herbal therapies in conjunction with prescription medications include heart irregularities (as my colleague experienced), uncontrolled bleeding or hypertension, difficulties with postoperative healing, or gastrointestinal issues (nausea and GI bleeding). Patients taking Warfarin or other anticoagulant medications should avoid herbal medication and should report OTC’s to their physician or provider, as well as any alteration in diet.4

Even though herbal substances sound natural and safe to consumers, they are not regulated by the FDA. They still contain potent chemicals, and they are not labeled with safety precautions. These medicines may interact with prescription medications or OTC’s in the following ways:

  • They may interfere with how the drug is broken down in the body, causing toxicity.
  • They may enhance side effects of a prescription medication.
  • They may block an intended therapeutic effect.1

Popular herbal agents with known interactions

Black cohosh

Black cohosh is often purchased over the counter by women experiencing hot flashes, or for those experiencing painful cramping during menstruation. Unfortunately, black cohosh may interfere with drugs that require liver metabolism, such as lipid-lowering medications. There is also a concern that black cohosh itself may be toxic to the liver. This drug should be avoided by anyone with liver disease (a history of hepatitis) or alcoholism.

Coenzyme Q10

This herbal has been widely used by people wishing to avoid heart disease and the aging process, although studies do not thoroughly support this premise. Taking this herbal can interfere with Warfarin and may cause a clot if the patient is unaware of the possible interaction.

Cranberry

Unlike CoQ10, cranberry has the opposite effect on Warfarin, and may cause increased bleeding. Cranberry has been used by women to avoid recurrent UTIs.

Echinacea

Echinacea is commonly used by those wishing to prevent a cold. Studies demonstrate it may be 10-20% effective at avoiding the onset of a new rhinovirus, although it will not shorten one already in progress. But… echinacea may slow the metabolism of caffeine, so it may keep you awake. Echinacea may also complicate the metabolism of prescription medications that require healthy liver function, so people on multiple medications should avoid this herbal.

St. John’s Wort

St. John’s Wort has waxed and waned in popularity, but it remains quite popular in Europe. It is often picked up by college students dealing with situational depression or anxiety. However, St. John’s Wort has multiple toxic drug interactions, which is complicated by the fact that many young people are not transparent about taking the medication. St. John’s Wort interacts with many medications that might be taken by young people or teens, including Dextromethorphan, birth control medications, HIV drugs, triptans for migraines, SSRIs, MAO inhibitors, and tricyclic antidepressants. Additionally, the herbal will interact with Warfarin and nefazodone. It is not a drug to be taken lightly.1

Melatonin

Melatonin first became popular with travelers who wanted to overcome jetlag. Lately, it appears to be on every television commercial for the sleep deprived. Melatonin has become mainstream. However, melatonin should be avoided with other medications that produce drowsiness, including cold preparations, benzodiazepines, muscle relaxers, etc. Melatonin should not be used in conjunction with alcohol, and it should be avoided by diabetics, who may become hypoglycemic during sleep. Melatonin may interfere with anticoagulants, causing blood clots.

Ginseng

Utilized for energy, ginseng has been sold as two different types, American and Asian. Ginseng has been ingested as an herbal to improve the body’s vitality for centuries, as well as to improve resistance to stress. Unfortunately, ginseng has multiple drug interactions and may enhance the properties of blood pressure medications. American ginseng may increase bleeding. Depending upon type, ginseng may also interfere with diabetic medications, or inversely, cause clotting depending upon brand.3

Gingko biloba

For centuries, Gingko biloba has been used for mental alertness and memory support. Gingko biloba has a long list of drug interactions (over 250) and should not be utilized by anyone on prescription medications, particularly seizure medications, without consulting a pharmacist.

Ginger

Ginger is often used to treat headaches and to prevent motion sickness or nausea. Ginger has also been used as a flavoring agent, and in some cases, to treat the nausea and vomiting of early pregnancy. Drug interactions with ginger are not well-known, but it has been hypothesized to cause prolonged bleeding times and interact with anticoagulants such as Warfarin, aspirin, and other blood thinners.3

Conclusion

While the desire to pursue a healthy lifestyle may include a wish to treat ailments with more “natural” options such as herbal remedies that can be purchased at a health food store or via the Internet, these agents are not regulated by the FDA. Batches may vary in dosage or quality from bottle to bottle, depending on where the herb is purchased. Herbals may also interact with OTC or prescription medications, resulting in potentially dangerous side effects or an absence of therapeutic results.

Although herbal medications have been utilized for centuries and will continue to have a place in easing pain, avoiding colds, and managing recurrent UTIs, among other indications, we must encourage people to take herbals safely. We should remember to follow the first rule of therapy, whether for self-care or for assisting our families or patients: “abstain from whatever is deleterious.”

References

  1. Drugs.com. 18 herbal supplements with risky drug interactions. Anderson, L., July 8, 2019, Drugs.com Mobile Apps.
  2. Healthline.com. 9 of the world’s most popular herbal medicines. Hill, A., February 3, 2020, Reviewed by Warwicki, K., Healthline Media.
  3. Medicinenet.com. Herbal toxicities and drug interactions. Shiel, W. C., Jr. Reviewed 3-4-2020, MedicineNet.
  4. Nccih.nih.gov. Herb-drug interactions. NCCIH Clinical Digest for Health Professionals, September 2015, U.S. Department of Health and Human Services, USA.gov.

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