Toxicodendron is a genus of plants, shrubs, vines, and trees within the Anacardiaceae family. Poison ivy is an allergenic plant in the genus Toxicodendron native to Asia and North America. It is well known for causing urushiol-induced contact dermatitis, an itchy, irritating, and sometimes painful rash, in most people who touch it. The rash is caused by urushiol, a clear liquid compound in the plant’s sap. The plant is variable in its appearance and habit, and despite its common name, it is not a true ivy (Hedera), but rather a member of the cashew and pistachio family (Anacardiaceae). T. radicans is commonly eaten by many animals, and the seeds are consumed by birds, but poison ivy is most often thought of as an unwelcome weed. Poison ivy was formerly treated as a single species, Toxicodendron radicans, but is now generally treated as a complex of three separate species:
Toxicodendron radicans (eastern poison ivy)
Toxicodendron rydbergii (western poison ivy)
Toxicodendron orientale (Asian poison ivy)
How common is a poison ivy rash?
Poison ivy, poison oak, and poison sumac are the most common causes of clinically diagnosed allergic contact dermatitis in North America. Approximately 50% to 75% of the US adult population is clinically sensitive to poison ivy, oak, and sumac.
Who might get a poison ivy rash?
It is possible that small percentage of people are “immune” to poison ivy, but anyone can get the rash throughout the lifetime. A poisonous substance producing rash is urushiol, which is capable of irritating skin in everyone.
Why not all people develop poison ivy? It is also possible that hypersensitivity highly depends on immune system condition. When immune system is calm and healthy, the rash might not develop (even with an extensive exposure). But it the immunity is hyperactivated by other problems (stress, leaky gut, autoimmune thyroid condition, chronic fatigue or infections) the reaction may happen then for the first time even if previous exposures were harmless.
What do poisonous plants look like?
Poison ivy is pervasive throughout North American and has been known to hybridize where their geographic distribution overlaps. Eastern poison ivy (Toxicodendron radicans) is commonly found in the eastern half of North America and typically appears as a vine with almond-shaped leaves in groups of three.
Leaves change from green to red in the fall. Western or Rydberg’s poison ivy (Toxicodendron rydbergii) is commonly found as a shrub with small yellow berries. It is distributed throughout much of North America, with the general exception of the Southeastern United States. All parts of both plants contain urushiol, which causes characteristic dermatitis associated with exposure.
What causes poison ivy eye reaction?
All parts of Toxicodendron plants contain urushiol, which is found in sap channeled within the plant. When exposed to air, urushiol turns black and hardens to prevent moisture loss and can be useful in identifying plants in the fall. Urushiol is the primary allergenic cause of contact dermatitis and is typically encountered by brushing up against damaged stems or leaves.
Exposure to the plants results in rapid absorption of the urushiol on contact due to its lipophilic nature. Names for the toxicity are variable and include names such as Rhus dermatitis, urushiol-induced contact dermatitis, and Toxicodendron dermatitis.
Poison ivy contains the oil urushiol gets on the skin or mucus membranes (in the eyes) and causes a type IV hypersensitivity reaction. The mechanism is the same as in any contact dermatitis (to cosmetics, metals, cleaning chemicals).
Signs and symptoms of poison ivy in the eye
The reaction on the face is always bad – too many sensitive areas like mouth, nose and eyes can get affected. The rash itself is not different when appears of the eyelids:
Redness and itching
Tiny blisters that turn into large blisters and pop later on
Areas of crusting
When should I call the doctor? You need an immediate treatment if:
You had bad reactions to poison ivy in the past and now re-exposed
The eye or eyelids are involved
You cannot open the eye
Rash is spreading all over the body and anywhere on the face
You have other systemic signs – chills, fever, malaise, headache
How is a poison ivy rash diagnosed?
Poison ivy rash diagnosis is simple if all the history is about outdoor activities right before the rash appears. It can be difficult to diagnose if you have other conditions of the eyes that could cause similar reactions, or if you started some new eye drops or contact lens.
Initial treatment for all contact reactions is the same, so even if a doctor does not know that it is really poison ivy, a course of oral prednisone will help reaction to go away, which can be also diagnostic. Other infectious rashes like Herpes Zoster will not respond to prednisone.
Poison ivy treatment
Treatment consists of topical measures of comfort and oral steroids. Do not rub or itch the eyes – it can make things worse. The oil may be spread to other areas of the skin or even inside the eye. A careful wash should be done from inside out around the closed eye. mild soap solution can be used, which should be then removed with plenty of water.
Warning! If there is a possibility that oil got inside the eye – do not treat it yourself. Go to the nearest open urgent care or eye doctor on-call. If that happened during the open office hours and you already have an ophthalmologist – call for urgent appointment.
Oral prednisone. This is a serious drug with a possibility of serious side effects. Yet, in the situation when poison got on the face, or if you previously had a severe reaction, prednisone is the best and only choice. In addition, when taken as a short course, steroids do not cause long-term problems. The usual side effects are:
Change of appetite (very hungry or not hungry at all)
Randomized controlled trial of adult patients (mean age 40) examined the efficacy and side effects of a 5-day regimen of 40 mg oral prednisone daily (short course) compared to the same 5-day regimen followed by a prednisone taper of 30 mg daily for 2 days, 20 mg daily for 2 days, 10 mg daily for 2 days, and 5 mg daily for 4 days over a total of 15 days (long course) in patients with severe poison ivy dermatitis. Patients receiving the long course regimen were significantly less likely to utilize other medications, although the outcomes were similar in different courses. This study suggests that a longer course prescription may save patients’ time and exposure to excess medication in the treatment of severe poison ivy.
Based on our experience, we recommend to have an extra prednisone at home if you, or your child already had at least one serious reaction in the past. You may start prednisone immediately while waiting for doctor’s appointment.
Other medications can be used to sooth the skin itch and reduce oozing of the blisters:
Hydrocortisone cream, OTC
Gold bond lotion, OTC
You should use extreme caution applying any creams around the eye area – it these creams or lotions get inside the eyes and the irritation of the conjunctiva can develop. It is best to get recommendations for eye care with poison ivy from an optometrist or ophthalmologist.
How long does poison ivy rash last?
The rash typically lasting for 1-2 weeks, unless a systemic reaction happens when it can continue in waves for 4-6 weeks. If you still have rash after 1.5 months that means you are getting re-exposure from some object you touched or clothes you were wearing when first exposure happened.
Poison ivy rash home remedies
Cool water compresses or herbal tea compresses is all you can use on or around the eye, as everything else can cause more irritation if gets inside the eye.
Menthol Cream or Lotion. We do not recommend to sue it on the face, definitely not on eyes! Menthol has a cooling effect on skin and is a substance that distracts from the itch. OTC products like Tiger balm, Gold Bond® anti-itch lotion, peppermint essential oil ( it is crucial that essential oils always be diluted for use on poison ivy rash).
Colloidal Oatmeal. While Colloidal bath products are available OTC, we recommend to grind it at home. 1 cup of powder-grinded oats is enough for a bathtub. It does not sink but evenly distributes on your skin, giving soothing effect. It might not be a good idea if there is significant blistering and oozing – you will need to use a towel after the bath to dry up your skin…
Witch Hazel. You can use natural cleanser that has no chemical additives or fragrances as compresses, or apply liberally with you hands.
Aloe Vera – natural gell that you can scrape out of the leaf can be used to dry up and heal blisters. Again – be careful when using on the face not to get it inside the eye.
Is poison ivy contagious?
No, but it can be transferred and smudged on surfaces that other people will touch – then everyone can get the rash.
How to prevent?
The best recommendation – do not touch it! “Leave of three – let it be”. A thorough wash of all surfaces, skin and clothes must be done immediately when you know that someone got into poison ivy. Don’t forget about pets – their fur can entrap oil if your dog ran into poison ivy on a walk.
Protective measures e.g. clothing, barrier creams, soaps, and solvents are often unsuccessful as oil can be on top of these barriers and then can be touched again.
Homeopathic treatment of poison ivy
The prophylactic oral administration of over-the-counter homeopathic poison ivy (HPI) to prevent allergic contact dermatitis from poison ivy is widely practiced among alternative medicine practitioners [3, 4]. Nevertheless, this clinical tip is not commonly known by conventional dermatologists. HPI is manufactured by preparing an alcohol extract from poison ivy leaves, which is then serially diluted and shaken to the desired strength (e.g. 1 x 10-60). Homeopathic medicines are regulated by the FDA as drugs as specified by the U.S. Food, Drug, and Cosmetic Act of 1938. They are prepared according to the homeopathic pharmacopoeia of the United States using good manufacturing practices.
For best results prophylactic treatment should begin one month prior to poison ivy exposure. It appears that the protective effect of HPI is lost about one month after discontinuation. Thus, protection does not appear to be permanent.