The use of natural herbal extracts in topical medications, for common
illnesses, has risen dramatically. One reason could be the introduction,
about 40 years ago, of the concept of ‘hypoallergens’ for
people with poor tolerance to cosmetics. The fallout was the promotion
of plant and herbal extracts, as safe products. This caught the popular
imagination and even the most skeptical were not left unaffected.
Despite such beliefs, herbal extracts must be seen as a potential source
of allergens. Patients often neglect to mention the use of herbal extracts
in their medical histories during contact dermatitis evaluations. Dermatologists,
therefore, need to be aware of the likely outcomes of the use of herbal
extracts in cosmetics.
Allergic contact dermatitis to individual extracts
ALOE: Aloe belongs to a family of mainly African plants of the genus
aloe and has been used to treat skin diseases since ancient times. There
is, unfortunately, very little research literature on aloe. It is now
an ingredient in many cosmetics. Contact dermatitis and urticaria have
been reported after application of aloe leaf extract in some people.
ARNICA FLOWERS: These belong to the genus of the Asteracae family. Arnica
montana has been used for centuries in cosmetics and to treat sprains,
wounds and other injuries. Many cases of contact dermatitis have been
reported due to arnica applications. Arnica tincture has been reported
to cause bulbous dermatitis after treatment of knee injury, and mild skin
trauma. A case of allergic contact dermatitis has been reported from sunflower
with cross sensitivity to arnica.
CENTELLA ASIATICA: Centella asiatica is an herbaceous
of the Apiaciae family and is known to help heal wounds. Vesicular contact
on the legs, thighs, face and trunk has been reported from the use of
creams containing this ingredient. Contact dermatitis to C asiatica has
also been reported in treatment of scars and morphea.
CUCUMBER: This is a widely cultivated plant. A 50 year old cook was reported
with hand dermatitis which spread to the face, from handling pickles.
Skin tests revealed positive reaction to cucumber.
GINKO BILOBA: This is a deciduous, dioecious native Chinese
tree with fan shaped leaves, fleshy yellow seeds and bad odor. Till now,
dermatitis cases have been reported from using preparations containing
G biloba ingredients. This may be because cosmetics do not contain the
plant’s fruit pulp, known to be the only part having allergens.
Studies suggest that G biboa may actually be able to reduce allergic contact
LAVENDER OIL: Lavender oil is extracted, for its fragrance, from the
purplish flowers of lavender, which belongs to a family of aromatic Old
World plants of the genus Lavandul. Two contact dermatitis cases have
been reported from use of lavender oil. One was due to sleeping on lavender-scented
pillows. The other was a case of acute facial dermatitis in a physiotherapist,
due to application of lavender scented gel. Patch testing showed positive
reaction to lavender. Fragrances and therapy oils containing lavender
have been reported to cause contact dermatitis.
PEPPERMINT: Peppermint oil is obtained from the mentha piperita plant,
a member of the Lamiaciae family. Its flowers yield a pungent oil. This
oil is distilled with steam from the flowering plant, rectified by distillation
but the menthol in it is not extracted. Peppermint is used to flavor tooth
pastes, candies, gums and mouth sprays for its cooling effect. It contains
at least 45% menthol. Contact reactions to peppermint result in burning
mouth, recurrent mouth ulcerations and lichenoid reactions in the mouth.
Peppermint oil has also been reported to cause contact dermatitis in fragrances
and occupational contact dermatitis in food handlers.
SAGE: Sage belongs to the family of plants, known as, salvia and is used
as a cooking herb. There are a few reported cases of contact dermatitis
associated with sage.
STINGING NETTLE AND CHAMOMILE: These are
used commonly in physiotherapy. Nettles have stinging hairs which cause
on contact. Nettle
hairs contain histamine and actylcholine which can cause these skin reactions.
Chamomiles are an aromatic perennial herb. Chamomile compresses cause
contact dermatitis, aggravate existing eczematous dermatitis, and also
causes photo allergic and airborne contact dermatitis. Chmomile is one
of them ost common herbs to cause dermatitis.
TEA TREE OIL: This oil is obtained from the leaves of a tea tree called,
Melaleuca alternifolia. The oil has been used to treat many diseases including
infections and psoriasis. Many cases of contact dermatitis to tree oil
have been reported.
No reported cases of contact dermatitis
Mention must also be made of plants and herbs about which there are no
reports of contact dermatitis. These include Angelica root, bladderwrack,
catnip, comfrey leaf, coriander, green tea, hops, licorice roots and marigold.
However, further investigations are needed to confirm their lack of allergenicity,
as current testing methods may be flawed.