When the itching won’t stop: Counseling on exposure to poisonous plants

One to One

With spring finally here, summer right around the corner, and the outdoors beckoning, many patients will be visiting their local drugstore or pharmacy seeking OTC treatments for poison ivy, poison oak, and poison sumac. Pharmacists are well positioned to counsel patients on preventing and treating exposure to these poisonous plants, the primary cause of allergic dermatitis in the United States.

Treatment options

A few hours to several days after exposure to urushiol—the light, colorless plant oil that causes the allergic reaction—patients will first notice itching, followed by a bumpy red rash, then blisters that begin to ooze and weep. Advise patients to remove all clothing and wash the affected area or areas with soap and cool water. Applying wet compresses or soaking the area in cool water may relieve itching. 

Caution patients against scratching the affected area or areas; though scratching does not spread the plant oil, bacteria underneath fingernails could cause infection. Inform patients that although urushiol is not contagious, it can be spread from contact with contaminated clothing or implements such as gardening tools, camping gear, and sports equipment. Pets also can come in contact with the plant oil and carry it on their fur. Clothing and implements should be washed immediately, and pets bathed if they may have been exposed.

Explain that most rashes caused by poison ivy, poison oak, or poison sumac are mild and last from 5 to 12 days. In severe cases, the rash can last for 30 days or longer. Inform patients of the wide variety of nonprescription treatment options available:

Antihistamines such as diphenhydramine (Benadryl or generic equivalents) relieve itching and help dry oozing and weeping blisters.

Corticosteroids treat a moderate to severe rash and come in several dosage forms, including topical creams, ointments, and gels. A few examples are Ivy Off; Cortaid Poison Ivy Treatment Kit; Extra Strength Benadryl Itch Stopping cream; Aveeno 1% Hydrocortisone Anti-Itch Cream; and All Stop Poison Ivy, Oak, & Sumac Healing Gel.

Skin protectants such as zinc acetate, zinc carbonate, zinc oxide, and calamine dry up oozing and weeping, while baking soda or colloidal oatmeal relieve minor irritation and itching. Aluminum acetate, an astringent, also may help with rashes.

When to see a physician

If these treatments do not ease symptoms, or for more severe reactions, advise patients to talk to their primary care provider about prescription oral corticosteroids such as prednisone or corticosteroid injections. 

Patients should also contact their primary care provider if they develop any of the following: a temperature over 100°F; pus, soft yellow scabs, or tenderness on the rash (indicating infection); itching that gets worse or keeps the patient awake at night; a rash that spreads to eyes, mouth, or genital area or covers more than one-fourth of the skin area; or no improvement within a few weeks.

Recognizing and avoiding poisonous plants

Poison ivy, poison oak, and poison sumac can be found in most areas of the United States, except Alaska, Hawaii, and the desert areas of the Southwest. Advise patients who spend a lot of time outdoors to wear long sleeves, socks, long pants with shoes or tucked into boots, and impermeable gloves in areas where they might be exposed. Use of an OTC topical product such as Ivy Block acts as a barrier against plant oil.

In addition, suggest to patients that they learn how to identify poison ivy, oak, and sumac plants to avoid exposure. One helpful resource is FDA’s Consumer Updates Web page, “Outsmarting Poison Ivy and Other Poisonous Plants.” 

Another good resource is The Poison Ivy, Oak, and Sumac Information Center, which contains FAQs, photographs, a list of products and treatments, a question-and-answer board, and links to other sites on poison ivy, oak, or sumac grouped by category.