In the past we’ve talked about many herbs that are safe and practical for use in natural products. But there are many herbs that were used in the past, and are now considered unsafe for use in the human, and often animal, system.
15 Herbs Considered Unsafe for Internal Use
Here is a partial list of herbs that are considered unsafe to use. Some do have external applications that are fine, but ingestion could be dangerous. Be sure to read each one carefully.
Once used for respiratory complications, tansy has been found to be a potential abortifacient, causing miscarriage in some women. However, it is safe to use in a DIY insect repellent. To make, soak the flowers and leaves in alcohol for a week, then strain and add water to double the volume. Spray around the house, inside and outside.
Arnica is potentially fatal if taken internally. However, arnica is a very useful herb externally for muscles and aching joints.
Although it contains dangerous aconite, monkshood was once used for treating disease. It has been found to be dangerous, even fatal, to use monkshood internally. Many other flowers in the Larkspur/Delphinium family share the same compounds and should not be used for natural products.
While foxglove does contain compounds that can help with heart rhythm, it should only be administered by a trained health care professional. Even a small error in amounts can cause death. It is safer to use hawthorn, as it regulates heart rhythm and can be used by anyone without side effects.
Due to the large amounts of safrole, a potential carcinogen, sassafras oil has been taken off many shelves. The root bark, used most often in cough preparations, is the highest in this compound. The leaves, ground and sifted, are fine used as Filé for gumbo and other stews.
6. Sorrel, Oxalis Leaves, and Rhubarb Leaves
These all contain oxalic acid in varying amounts. Rhubarb leaves should never be used, but the stem makes a tasty treat. Sorrel and oxalis should not be used raw or in large amounts.
Formerly used in cough and cold preparations, yew contains enough poison to prove fatal to a small dog. Do not use in any form.
8. Mountain Laurel, Rhododendron, and Azalea
These plants all contain toxins. Even honey from any of these evergreen shrubs is poisonous.
Many old timers still believe pokeweed is safe, but even just a few berries can poison a child. The leaves contain alkaloids that can be leached out after changing the water several times while boiling. It’s not recommended in any case.
10. Cascara Sagrada
Often used in laxatives, fresh cascara sagrada bark can cause nausea. Prolonged use can lead to chronic diarrhea.
Although most all of the flowers in the Hibiscus family are edible, the seeds of the cotton plant are extremely toxic. Luckily, the toxins are removed in the ginning process, so your jeans and sheets are safe to use.
Elderberry is most often used in syrups to fight off colds and flu. It has powerful antioxidants that combat disease. However, the fresh berries must be processed in some way, such as boiling, freezing, or drying – fresh berries contain a toxin that is broken down in processing.
Datura and Brugmansia are in the same family as jimsonweed. In small amounts the seeds produce hallucinations, but too many can lead to convulsions and death. Much is dependent on body weight and it is difficult to get the right amount, so it’s best avoided.
Often used in herbal pest control, it can cause miscarriages if taken internally. Even the essential oil can be dangerous to pregnant women, and should be avoided entirely.
15. Castor beans
These beans yield castor oil which is used in hair and skin products. But first, the deadly toxin ricin must be removed. Castor beans have been marketed for ridding yards of moles, but it has been banned in many states because of the dangers it poses if accidentally swallowed.
This is only a partial list of some of the herbs that can be harmful. Common sense, such as not using herbs from areas where pesticides or herbicides have been used, should always be exercised. And always get permission when harvesting herbs on another’s property. When trying something new, use small amounts to be sure your body will react well.