Good Advice for Gardeners: What's That Rash?


Poisonous life overwhelms many gardens, and as summer arrives and patients head outside, poison ivy becomes a timely concern.

Poisonous life overwhelms many gardens, and as summer arrives and patients head outside, poison ivy becomes a timely concern.

Many patients forget to wear protective clothing while doing yard work, which leaves them vulnerable to accidentally encountering poisonous plants. Many others are unaware that OTC barrier topicals containing quaternium-18 bentonite can prevent rash.

Retail clinicians are well-placed in their communities to ensure patients are aware of the types of poisonous plants and how they can protect themselves from exposure.Poison ivy, poison oak, and poison sumac are well-known for their urushiol-containing sap. Approximately half of American adults are sensitive to these plants and can develop an itchy red rash up to 4 days after exposure. As the rash ripens, blisters usually appear in streaks.

Patients may fail to realize that direct contact isn’t the only way to develop a rash from urushiol oils. The oils can also persist on gardening tools, gloves, and clothing, while pets can carry the oil to unsuspecting humans.

Airborne contact is possible if the plants are burned, which releases urushiol into the air. Airborne exposure usually leads to widespread rash and can cause severe irritation in the respiratory tract.

Good gardening advice is, “Leaves of 3, let it be,” but poison ivy and other urushiol-containing sap plants aren’t the only rash-producing plants in the petunia patch. Retail clinicians should advise their outdoorsy patients to be wary of the following plants:

â–ºStinging nettle plants are carpeted with sharp hairs resembling tiny hypodermic needles. A quick brush on exposed skin can lead to histamine or acetylcholine release and blotchy hives within an hour of exposure. The rash usually resolves spontaneously in a few hours. Strawberries, onions, garlic, tulips, and lilies can also cause hives.

â–ºSpiny, thorny, or glochid (barbed spine or bristle-bearing) plants can deposit plant material in the dermis, causing itchy, bumpy eruptions. Usually, the rash resolves without incident, but irritated areas can become infected with staph or fungal infections.

â–ºSome patients react to goldenrod, daisy, or tansy, which contain sesquiterpene lactones.

â–ºRue, a spring-blooming plant with pretty blue-green foliage, can cause phytophotodermatitis—a rash caused by 1) exposure to a plant that contains psoralens, and 2) followed by exposure to ultraviolet light. Giant hogweed, limes, Queen Anne’s lace, bergamot oranges, and celery can also cause this reaction.


Treatment depends on the patient’s exposure and reaction.

If spines, thorns, or glochids are implicated, they should be removed carefully with tweezers. Some particles are extremely small; for these, apply glue and gauze to the site, allow it to dry, and peel it off.

Minor itching, irritation, or rash can be treated with oral antihistamines or OTC topical steroids. If the rash is more extensive or uncomfortable, a more potent topical steroid can be considered. Severe rash mandates a strong topical steroid or a 2- to 3-week course of oral steroids.

For poison ivy, poison oak, and poison sumac, retail clinicians should advise lukewarm baths and soaks with products containing aluminum acetate, calamine, or topical steroids. Additionally, oral antihistamines will lessen itching and skin irritation, but avoid topical antihistamines. Some patients are allergic to these products, which can aggravate the problem.

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