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Herbal Supplements and Drug Interactions

Wednesday 26 December 2018
Health & Wellness
5 minute(s) read
By Anonymous

With the global herbal supplements market expected to reach $86 billion by 2022, more people are using herbal and dietary supplements as preventive or curative medicines. But some herbal supplements come with potential drug interactions and dangerous side effects.

  • The FDA doesn’t test supplements to ensure what you’re buying is actually what it’s labelled as. So while an herb may have been thoroughly tested for safety, there’s no guarantee that what you’ve purchased matches the exact chemical or concentration on the label.
  • Herbal supplements aren’t required to include drug interaction warnings on their labels. If a supplement is what it claims to be, you may still be in the dark about how it interferes with common medications.

Herbal supplements are often considered safer than prescription drugs, but both have chemical actions in the body. Most people think of herbal supplements as inherently safe, and don’t think to tell their doctor exactly what they’re taking.

8 Popular Herbal Supplements with Drug Interactions

1. Cranberry

Cranberry juice and extract are popular herbal remedies to prevent recurrent urinary tract infections. But cranberry may act as a blood thinner, making it potentially dangerous to take alongside blood thinning drugs like warfarin or aspirin.

An occasional glass of cranberry juice is unlikely to cause problems, but you should clear it with your doctor before mixing daily cranberry with blood thinners.

2. Black Cohosh

The roots of the black cohosh plant have been used as a medicinal for centuries, and are a popular herbal remedy today for menopausal symptoms like hot flashes.

Black cohosh may lower blood pressure, and anyone taking blood pressure medication (diuretics, beta blockers, ACE inhibitors, vasodilators) should clear this supplement with their doctor beforehand.

3. Evening Primrose Oil

Derived from the flowering evening primrose plant, there are claims this herbal remedy can do everything from treat liver disease to shorten labor. Today the most popular use of evening primrose oil is as a treatment for eczema, but the herb can have unintended consequences.

  • Increased bleeding: Don’t take evening primrose oil with blood thinners unless expressly approved by your doctor.
  • Low blood pressure: People with vascular conditions or who are taking blood pressure medication should avoid evening primrose oil.

4. Valerian Root

Valerian is a popular herbal sleep aid, and studies suggest that the root does improve sleep quality. Researchers aren’t exactly sure how valerian aids sleep, but mixing it with other sedatives may cause added drowsiness or sedation. Avoid taking valerian with:

  • Prescription sleep aids (Ambien, Lunesta, Sonata)
  • Benzodiazepines (Xanax, Valium)
  • Alcohol
  • Anti-seizure drugs

5. St. John’s Wort

St. John’s wort is a popular herbal remedy for depression, and may work by increasing serotonin levels in the body. But taking St. John’s wort can impact the efficacy of important prescription drugs.

  • SSRIs: A class of antidepressant drugs that increase the amount of serotonin in the body, taking SSRIs with St. John’s wort can result in a dangerous excess of serotonin. 
  • Oral contraceptives: St John’s wort appears to reduce the effectiveness of oral contraceptives, and may make emergency contraceptives less effective.
  • In addition to birth control, St. John’s wort may increase the metabolism of antibiotics and other drugs, reducing their effectiveness.

6. Melatonin

Often referred to as the “sleep hormone”, melatonin is produced naturally by the body and regulates our sleep and wake cycles. Melatonin supplements are suggested for people with jet lag or sleep onset insomnia.

  • But popping extra melatonin may not be a good idea if you’re also taking:
  • Sedatives: Mixing multiple sedative drugs can have synergistic effects that make you too groggy to function.
  • Anticoagulants: Melatonin is one of the many supplements that appears to slow blood clotting. Avoid taking it if you’re on warfarin or another drug that increases bleeding.
  • Blood pressure medication: Melatonin could raise your blood pressure, counteracting the effects of any prescription drugs you’re taking to control high blood pressure.

7. Yohimbe

Yohimbe is a stimulant that’s marketed as an aphrodisiac, erectile dysfunction treatment, and weight loss drug. These products are being increasingly scrutinized for false or unclear labelling, and should not be used by:

  • People taking MAOIs or other antidepressants.
  • Patients with heart, kidney, or liver disease.
  • Anyone with a history of panic and anxiety.

8. Ginseng

Ginseng has a long history of use in Asia and North America, but should be taken cautiously by people with problematic blood pressure or diabetes.

  • American ginseng has been found to reduce the effect of anticoagulant drug warfarin.
  • Some types of Asian ginseng appear to act as blood thinners, which can make you more prone to bleeding and disrupt treatment with blood pressure medications. 
  • Ginseng might lower blood sugar levels, which can interfere with regular diabetes treatment.

Avoiding Drug Interactions

If you’re interested in trying out an herbal supplement or already take one, there are several ways you can reduce the risk of drug interactions and side effects.

  • Tell your doctor and/or pharmacist about all drugs and supplements you’re currently taking.
  • Educate yourself on the potential symptoms of herbal/drug interactions.
  • Only purchase herbal supplements from reputable brands, and look for third-party certification on labels from USP (United States Pharmacopeia), NSF International, or Consumer Lab.
  • When taking a new herbal supplement or combining one with prescription drugs, begin by taking half the recommended dose of the supplement. This can account for inaccurate labelling and reduce the severity of adverse reactions.
  • Be extra cautious of products marketed for weight loss, sexual enhancement, or bodybuilding. These supplements often contain active prescription ingredients that aren’t listed on the label.

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DISCLAIMER: The content in this article is intended for informational purposes only. This website does not provide medical advice. In all circumstances, you should always seek the advice of your physician and/or other qualified health professionals(s) for drug, medical condition, or treatment advice. The content provided on this website is not a substitute for professional medical advice, diagnosis or treatment.