Allergic to “natural”: plant extracts, propolis and botanicals

Many people switch to plant-based skin care because they hope it will be kinder to their skin. Sometimes it is. But plants make chemicals too, lots of them, and some are genuine skin allergens. If you’ve reacted to a “natural” cream and felt a bit betrayed, you’re not alone, and there’s a good scientific reason for it.

Why “natural” doesn’t mean gentle

To your immune system, a molecule is a molecule. It doesn’t care whether it was squeezed from a flower or made in a lab. What matters is whether it can bind to skin proteins and teach your immune system to react, the process called sensitization that leads to allergic contact dermatitis, an itchy rash a day or two after contact.

Plant extracts are often complex mixtures of many compounds. That’s part of their appeal, and part of the problem: every extra compound is another chance for your skin to meet something it doesn’t like. Health Canada makes the same point about natural health products in general: some people assume that because a product is labelled natural it is safe, but these products can have side effects, including allergic reactions.

How common is it? A 2024 study from the Mayo Clinic looked at 20 years of patch testing, the clinic test for skin allergies, with botanical ingredients. Of more than 12,000 people tested, almost 11% reacted to at least one botanical. Rashes most often showed up all over, or on the hands or face. And people who reacted to one botanical were more likely to react to another.

The daisy family: chamomile, calendula, arnica and friends

One of the best-known plant families behind skin allergies is the Compositae, also called Asteraceae or the daisy family. DermNet notes it includes about 20,000 species, roughly 10% of all flowering plants. Members you’ll see on labels or in the garden include:

• Chamomile
• Calendula (marigold)
• Arnica
• Echinacea
• Feverfew
• Chrysanthemum, dandelion, sunflower and ragweed

The allergens are called sesquiterpene lactones, found in the leaves, stems and flowers. DermNet says gardeners, farmers, florists and forestry workers are at particular risk, and that reactions can appear on exposed skin like the face, neck, hands and arms because plant particles can be carried in the air.

The practical upshot: if you’re allergic, DermNet says creams and cosmetics containing daisy-family extracts should not be used. That includes some soothing baby balms with calendula, arnica gels for bruises and chamomile-based “calming” creams. Eating vegetables from this family, such as lettuce, is generally fine.

There’s also overlap with fragrance allergy. DermNet reports that more than a third of people with Compositae allergy also react to fragrance, balsam of Peru or rosin (colophony, a pine resin).

Propolis: the bee glue

Propolis is the sticky glue honeybees make from tree resins and beeswax to build, repair and protect their hives. DermNet says people meet it through some cosmetics, oral care products and natural remedies.

European patch-test studies have found positive reactions to propolis in 1.2% to 6.6% of people tested. Beekeepers are the classic group, with an average of about nine and a half years of exposure before becoming allergic. Reactions can include hand dermatitis, inflamed lips and mouth sores.

Here’s where the story gets more nuanced. Propolis shares 13 known components with balsam of Peru, a fragrance-related resin, and DermNet notes the two often cross-react. A 2026 review in Contact Dermatitis checked the ingredient lists of 500 leave-on cosmetics in the Netherlands and found none that listed propolis. The authors suggest many positive propolis tests may reflect earlier fragrance allergy rather than exposure to propolis itself.

What about beeswax, which can contain traces of propolis? The same review found reactions to beeswax in propolis-allergic people are uncommon and mostly involve lip balms. Its conclusion: people with a positive propolis test don’t need to avoid all cosmetics that contain beeswax.

Balsam of Peru and essential oils

Two other natural ingredients come up again and again in allergy clinics.

Balsam of Peru is a fragrant tree resin. It was the most common positive allergen in the Mayo botanical series, and DermNet notes it often cross-reacts with propolis and with fragrance ingredients.

Essential oils are concentrated plant scents, and many contain limonene (from citrus) or linalool (from lavender and other flowers). DermNet explains that both oxidize on exposure to air into hydroperoxides, which are much stronger allergens, and that 10% of people investigated for suspected contact dermatitis were allergic to these hydroperoxides. An essential oil can be completely natural and still be a potent allergen once the bottle has been open a while.

If you want to avoid added scent, filtering for fragrance-free products is a good start, but still read the ingredient list for essential oils and plant extracts.

How to find out what you’re reacting to

If you suspect a natural ingredient, the answer is the same as for any other contact allergy: patch testing. DermNet notes that a standard sesquiterpene lactone mix and a chemical called parthenolide pick up about 75% of Compositae allergies, and specific plant extracts may be needed to confirm the rest. Propolis has its own test allergen.

Because standard panels don’t cover every plant, it helps to:

• Bring the products you suspect, in their original containers, so the clinic can see the full ingredient list and possibly test the product itself.
• Mention herbal remedies, teas used as compresses, gardening and beekeeping.
• Report reactions. Health Canada encourages people to report side effects from natural health products.

In the meantime, stop the suspected product, use a very plain moisturizer, and see your doctor or pharmacist if the rash is spreading, on your face or eyelids, or not better after two weeks.

To sum up: natural ingredients can be excellent, but they aren’t automatically gentler. The daisy family, propolis, balsam of Peru and essential oils are all known skin allergens, and about one in nine people patch tested at one major clinic reacted to at least one botanical. If a plant-based product gives you a rash, treat it like any other allergy: stop it, keep the label, and ask about patch testing.