What Are the Side Effects of Herbal Medicine?

What Are the Side Effects of Herbal Medicine?
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Plants as Medicine

There are hundreds, if not thousands of plants that possess properties which can assist the human body with healing and reaching a state of balance. Some stimulate circulation, others improve digestion, relax the nerves, tone the glandular system, support the liver, or numerous other actions. While there are many benefits of choosing a natural form of healing such as herbs, which attempt to improve overall well-being rather than merely suppressing symptoms, there are also potential risks to be aware of, especially if used improperly or in conjunction with prescription medications.

Without regulation by the US Food and Drug Administration, those who are interested in herbs really have to seek out the information themselves in regards to the safety of the plants. What are some of the more common side effects of herbal medicine? What about overdosing and allergic reactions? How can someone new to herbs safely use them?

Common Side Effects

Common side effects of herbs vary with the specific action of the herb, but may include dizziness, nausea, raised blood pressure, sweating, sedation, and skin rashes. Possible adverse affects of some of the more commonly used herbs include:

  • Sage, interferes with iron absorption and can decrease milk in nursing mothers
  • Motherwort can stimulate uterine contractions and may cause problems with people who have heart disease, high blood pressure, or clotting disorders
  • Meadowsweet contains compounds that are similar to aspirin and should not be given to pregnant women or children because aspirin can increase the risk for Reye’s syndrome
  • Licorice root can elevate blood pressure
  • Kava kava can cause drowsiness
  • Hops can aggravate depression
  • Ginseng can affect blood pressure
  • Ginkgo biloba can cause internal bleeding if used with blood thinning or pain medications
  • Ginger can cause upset stomach


Taking more than the prescribed dose can definitely cause problems. Herbs are powerful medicinal plants and too much of one action is not beneficial. Herbs such as poke root, which is an emetic plant, will cause vomiting. Parsley in large amounts may stimulate the uterus and can be dangerous during pregnancy. Buckthorn, a natural laxative, can cause an excessive reaction if taken in high doses. Taking more than the recommended doses of herbal medicine, just like with conventional medicine, can upset the body’s natural balance, put strain on the organs of elimination, and do more harm than good.

Allergic Reactions

Another potential problem with herbs is an allergic reaction as a side effect. Chamomile for example should not be used in cases of an allergy

chamomile side effects

to ragweed. Signs of this adverse reaction include skin rashes and upper respiratory tract problems. If you have allergies to certain plants or foods, talk to your doctor when choosing herbs.

Using Herbs Safely

If there are so many side effects of herbal medicine, how can herbs be used safely? First, learn more about each herb you plan on using. What are all the medicinal properties? Are there any drug interactions? Could you be allergic? Second, only purchase herbal products from a trusted source. Capsules, powders, and tinctures are not regulated by the FDA so you have to investigate the company you are buying from as well. Third, talk to your doctor. Having an open relationship with your health care professional about alternative forms of medicine that you plan on using is a great way to treat yourself safely. Especially if you take any form of prescription or over-the-counter medication, are pregnant, or if you have any medical condition, check with your doctor first.


American Academy of Family Physicians https://www.aafp.org/afp/990301ap/1239.html

Hoffmann, David. “The Complete Illustrated Holistic Herbal: A Safe and Practical Guide to Making and Using Herbal Remedies.” (Element Books, 1996).

Balch, Phyllis A. “Prescription for Nutritional Healing.” Fourth Edition (Penguin Books, 2006).

photo by Eran Finkle (CC/flickr) https://www.flickr.com/photos/finklez/3133961324/

photo by Salvadonica Borgo del Chianti (CC/flickr) https://www.flickr.com/photos/salvadonica/4534134681/


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