Possible Complications of Herbal Medicine

Complications of herbal medicine are possible. Natural plants and herbs contain compounds that aid in healing and treatment; however, the word natural does not imply all plants are safe and free from risk.  

Herbal medications are naturally occurring, as opposed to synthetically produced conventional medications. However, side effects and complications are possible with herbal, as well as conventional medications. 

Herbs and Anesthesia

Some herbs interact with anesthesia. In most cases, the herbs prolong the recovery period. Patients do not wake from general anesthesia, as quickly as they should. 

Some examples include Kava kava and St. John’s wort. Both herbs are used to treat minor anxiety and depression. Compounds found in these herbs are similar to those found in anesthesia. Valerian may also delay recovery from anesthesia. Valerian is commonly used in the treatment of insomnia. 

Your doctor may request that you discontinue use of any herbs prior to, and immediately after surgery. 

Herbs and Surgery

Researchers have identified several herbs that can cause bleeding complications during and after surgery. Ginseng, garlic, feverfew, peony, cinchona bark and gingko biloba are some herbs that increase the risk of bleeding. These herbs dilate blood vessels and increase blood flow. These herbs are generally used to treat inflammation and circulatory disorders. 

Herbs also have the potential of creating cardiovascular complications during surgery. Licorice and ginseng, along with many others, can cause cardiac arrhythmia, stroke and heart attack. 

If you are taking any herbal preparations, discuss this with your doctor prior to surgery.

Herbal and Conventional Medicine Interactions

Individuals taking anticoagulant medications should consult with their physician or health practitioner before taking any herbs. Gingko biloba, ginger, cinchona bark, St. John’s wort and psyllium can increase the effectiveness of anticoagulants or Aspirin. 

Consuming large quantities of garlic or taking garlic supplements, in addition to anticoagulants, can also increase risk of bleeding and hemorrhage. 

Herbs may also affect the effectiveness of conventional blood pressure medications. Goldenseal can interfere with blood pressure medication by reducing its effectiveness. This is also true of ginseng. You should not take hawthorn or licorice, if you are taking medication to treat hypertension. This combination can cause blood pressure to drop to a dangerous level. 

Evening primrose and borage should not be used by anyone taking Phenobarbital to treat seizure disorders. These herbs will reduce the effectiveness of Phenobarbital.  If you are taking an MAO inhibitor to treat depression, you should not take St. John’s wort. The affects of St. John’s wort are similar to MAO drugs. Taking both is a dangerous combination. Additionally, St. John’s wort may interact with over the counter cold medicines. 


All herbs have the potential to induce an allergic reaction. If you are an allergy sufferer, you may be at higher risk of an allergic reaction to some herbs. Individuals who are allergic to daisies should avoid taking feverfew. Both plants belong to the same family. 

Yarrow, juniper, dandelion and plantain are some herbs that commonly cause allergic reactions. 


Pregnant women should speak to their doctor before consuming any herbal products. Ginseng may cause birth defects. Peony has the potential to induce labor. Many herbs may increase the risk of bleeding. Many herbs that are ordinarily considered safe may not be safe for pregnant women.