Do Herbs Have Side Effects?

Many people assume that because herbs are natural that they are completely safe. I was even watching a show where the woman was growing her own medicinal herbs and listening to her talk, it seemed like she knew what she was talking about. Then, she said "herbs are natural and they don't have any side effects."


I have also heard from MLM distributors or advocates, that because essential oils are natural, they don't have any side effects and that any perceived side effects are caused by 1) inferior oils and 2) detox reaction.


At this point you are probably realizing that yes, herbs have side effects. HOWEVER, most of the time the side effects will be mild and will go away without causing any permanent damage by just stopping the herb...unlike conventional medications which can cause additional health problems.

What Kind of Side Effects Do Herbs Have?

Allergic reaction

This one is pretty self explanatory but sometimes people don't realize that they are allergic to a plant, or the plant family, until they are trying herbs for the first time.

One common "offender" is Chamomile and the daisy family, or Asteraceae family. This family includes the plant ragweed as well. So if you have an allergy to ragweed, proceed with caution when trying Chamomile.

Symptoms could be similar to seasonal allergies...itchy eyes, running nose to hives. Discontinue taking the herb and in an hour or so it will have cleared your system.

Topical Irritation

Most of the time, this will occur with use of essential oils. No, that burning feeling isn't an inferior oil or a detox reaction (there is no such thing with essential oils) is a reaction from the essential oil. Wash with soap and water, then cover the area with a carrier oil. DO NOT USE JUST WATER.

Some hot cayenne...can cause irritation if used in a formula that has too much cayenne or you have been using it for longer than you should.

This side effect can be a red rash, itching, or burning.

As we talked about in allergic reaction, applying an herb topically can also trigger an allergic reaction...if you are allergic.


While I love being able to use herbs to help with pain, nervous system issues, and sleep....sometimes they can be quite strong, especially for those individuals who are sensitive to herbs and medications. I always tell people that when trying an herb that is sedative in nature (like California poppy, Valerian, or Passionflower) to try it at home when they don't have to go driving anywhere. 

Obviously, sometimes this is the desired effect (like to help with sleep). I have included it here so that people will try the sedative herb first at home.

Herb/Drug Interactions

Some herbs will interact with conventional medication. A well known interaction is with St John's wort (Hypericum perforatum) and birth control pills. St John's wort, because of how it affects a liver enzyme in our body, can decrease the effectiveness of other medications.

Other interactions that can react with herbs...blood thinners and therapeutic doses of garlic (which therapeutic doses of garlic should be discontinued 10 days before any surgery).

While the a lot of herbs will be safe for you, please contact an herbalist for consult.

Toxic Constituents

This is difficult topic because in many cases, herbs that contain "toxic constituents" are fairly safe when taken in whole plant form for a short period of time. However, it does deserve a spot here. A local herb store in our area won't even sell herbs that contain alkaloids...a decision I respect but don't agree with (that leaves out herbs like Comfrey and Coltsfoot).

Please, if you use Google to learn about the constituents of a plant, also contact an herbalist.

One example is an herb I just talked about last week....Oregon grape root. OGR contains a kind of alkaloids called, isoquinoline alkaloids. The plant contains low levels and is quite safe for use. Looking at Medical Herbalism by David Hoffman, he lists no additional safety considerations. In the AHPA Botanical Safety Handbook, any reported effects were from the isolated constituent, not the whole plant form, done in studies on mice.

Rest assured that most of the herbs the family herbalist will use won't carry a high risk for side effects. The safest way to use herbs is in their whole form. Plants have 100s or 1000s of constituents and many times balance themselves out.

I also stand strong in my belief that herbal medicine can be used (and should be, if I might be so bold) by everyone. It is widely used around the world as a primary form of medicine and has 1000s of years of use in some areas.

If you have any concerns, visit an herbalist!