Rumour: “Natural and herbal treatments have no side effects” — What does the science say?

Short answer: “natural” is a marketing word, not a safety certificate. Plants are also made up of chemical substances, and some of these can cause allergy, irritation or burns in combination with sunlight on the skin. With products given by injection, a “natural” claim provides no guarantee at all; what matters here is the product’s licence, its source and who carries out the treatment.

Where does the rumour come from?

The word natural suggests something clean, gentle and harmless. The fact that the side effects of synthetic medicines are listed at length in package leaflets, while herbal products often carry no such warning, reinforces this perception. Yet the absence of a warning on a product’s box usually shows not that it carries no risk, but that the risk has often not been systematically studied.

Can plant extracts cause allergies?

Yes. The dermatology literature has reported that many plant extracts used in cosmetic products cause allergic contact dermatitis, that is, an itchy, red, sometimes weeping eczema where the product touches the skin. Plants of the daisy family, tea tree oil, mint, lavender and henna are among the examples often mentioned. Sometimes the problem comes not from the plant extract itself but from the fragrance, preservative or dye added to the product.

Essential oils require particular care. A scientific review reported that nearly eighty essential oils have caused allergies, and noted that most reactions developed when pure oils or highly concentrated products were applied directly to the skin. Some essential oils can become more allergenic as they come into contact with air and age.

For the signs of allergy and what to do in serious reactions, see our article “Allergic Reactions in Aesthetic Treatments”.

Some plants can cause burns and dark spots in combination with sunlight

Substances called furocoumarins (psoralens), found in some plants, trigger a burn-like reaction when they combine with sunlight after coming into contact with the skin. This is called phytophotodermatitis. Citrus fruits such as lemons and limes, fig leaves and some plants of the parsley family have been linked to this type of reaction.

The reaction can start with redness, burning and blistering; as it heals, it can leave brown marks that last for weeks, sometimes months. This is why home remedies such as lightening dark spots with lemon can have exactly the opposite effect. For dark spots, our article “Dark Spots and Melasma” describes safer approaches.

Are natural products also safe after aesthetic treatments?

After procedures such as laser, chemical peels or microneedling, the skin barrier is temporarily weakened. During this period, substances applied to the skin are absorbed more easily, and the risk of irritation, allergy or infection may increase. Homemade masks, honey, yoghurt, vinegar, lemon or essential oil mixtures can therefore cause problems in the period after a procedure. During healing, it is safer to use only the products your physician recommends.

Are the contents of herbal products always known?

Not always. The concentration of an extract obtained from the same plant can vary depending on growing and processing conditions. Products with weak oversight may also contain substances not listed on the label, heavy metals or microbial contamination. Licensed or registered products with traceable quality reduce this risk; but they do not eliminate it.

Is there really such a thing as herbal filler or herbal botox?

No product injected under the skin can be considered natural. The skin is the body’s most important barrier against germs and foreign substances; once this barrier is crossed with a needle, the sterility and contents of the product and how it behaves in the body become decisive. This is why injections are medical procedures that should be carried out with strictly regulated products and by a physician.

Expressions such as “herbal filler”, “natural botox” or “needle-free herbal rejuvenation” are mostly marketing language. The contents of products sold under these names may be unclear; sometimes an unlicensed or counterfeit injectable product is presented as “natural”. The U.S. Food and Drug Administration (FDA) warns that filler products sold directly to the public or online may be counterfeit, contaminated or unapproved. For details, see our article “Counterfeit Products and Unlicensed Treatments”.

So should natural products never be used?

This article does not say that natural products are bad. Many substances of plant origin are found in well-studied cosmetics and medicines that are used safely. The point is not to treat “natural” and “safe” as the same thing. Like any product, herbal products should be assessed according to their contents, concentration, the way they are applied and the person’s skin.

• Before applying a new product to your face, read its label; make a note of any plants or fragrances you have reacted to before.
• Do not apply pure essential oils directly to the skin.
• Take care if you are going out in the sun after using products containing citrus or plant extracts; protect yourself from the sun.
• If redness, itching or burning occurs, stop using the product and rinse the area with water without soap; if it does not go away, see a physician.
• With recurrent reactions, a dermatologist can use patch testing to find the substance responsible.
• Before an aesthetic treatment, also tell your physician about any herbal products and supplements you use; some can increase the tendency to bruise.

Conclusion

The rumour that natural and herbal treatments have no side effects is not scientifically correct. Plants can also cause allergy, irritation and reactions with sunlight, and no product given by injection can be considered natural. What determines safety is not the word on the label but knowing the contents, the source of the product and who carries out the treatment. Scientific knowledge in this area is still limited for many plant extracts; if you are unsure, consult your physician.