What are the other Names of this Condition? (Also known as/Synonyms)

• Rhus Dermatitis
• Toxicodendron Dermatitis
• Urushiol-Induced Contact Dermatitis

What is Poison Plant Allergy? (Definition/Background Information)

• Poison Plant Allergy is a common condition that manifests as an abnormal immune reaction/response to certain plants that are denoted as being poisonous (or allergy-inducing). It is observed in both children and adults
• Some of the common allergy-causing poisonous plants around the world include:
  • The trio of poison ivy, poison oak, and poison sumac plants
  • Burmese, Chinese, or Japanese lacquer tree
  • Mango tree
  • Marking nut tree of India
  • Gluta renghas tree of Indonesia and Malaysia
  • Cashew nut tree
  • Pistachio plant
• Poison Plant Allergy may occur immediately, or within hours following exposure to the plant, which may occur through touch, ingestion (eating plant parts), or inhaling smoke from burning plants. The condition may be mild, moderate, or severe
• Numerous signs and symptoms of the allergic reaction may be noted including skin rashes and hives, sneezing, breathing difficulties, nausea and vomiting, and indigestion. In some individuals, Poison Plant Allergy may lead to an anaphylactic shock, which is a medical emergency. The condition is generally diagnosed based on clinical signs and symptoms
• Anti-allergic medications form the first line of treatment for mild cases of Poison Plant Allergies. Corticosteroid therapy may be necessary to reduce inflammation. However, in the case of a severe allergic reaction (anaphylaxis), epinephrine injections are recommended
• The prognosis of Poison Plant Allergy is generally good with appropriate treatment. In many, the condition resolves in a few weeks’ time. However, the condition can recur on repeat exposure to the plant

Who gets Poison Plant Allergy? (Age and Sex Distribution)

• Poison Plant Allergies affect both children and adults. It is reported that over 90% of the individuals may be allergic to a variety of poison plants
• No gender preference is noted and both males and females are affected
• All racial and ethnic groups are equally vulnerable to the condition

What are the Risk Factors for Poison Plant Allergy? (Predisposing Factors)

The common risk factors for Poison Plant Allergy include:

• Direct contact with the shrub, or plant, or tree
• Eating parts (leaves, fruits, seeds) of the plant
• Inhaling smoke of burning (dead) plants
• Contact with garden equipment, lawn-mowers, pets that have been exposed to the plants, etc.
• Infants and young growing children may have a higher risk for Poison Plant Allergy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Poison Plant Allergy? (Etiology)

An allergic reaction occurs in an individual with Poison Plant Allergy, because the immune system recognizes certain substances/components in the plant as being dangerous and harmful to the body.

• The poison plant contains a toxin called urushiol, a strongly allergy-inducing organic oil, which is found in most plant parts 
• Contact of the skin or mucus membrane with this chemical (oil) results in the production of antibodies. The next time the individual is exposed to the particular substance, the antibodies that are circulating in blood causes an antibody-antigen reaction
• This results in the production of histamine and other chemical messengers, which cause the symptoms seen during an allergic reaction

In some cases, a severe allergic reaction termed as anaphylaxis may occur, which is a medical emergency that requires immediate medical attention.

What are the Signs and Symptoms of Poison Plant Allergy?

The signs and symptoms of Poison Plant Allergy may start to appear within a few minutes, a couple of hours, or even days after the individual has been exposed to the toxin from the plant. In some, the symptoms are mild, while in others they may be severe. It also depends on the type of plant causing the allergic reaction. A severe allergic reaction is a medical emergency.

The signs and symptoms of Poison Plant Allergy may include:

• Itching at the site of skin contact; the itching can be severe to extreme
• Itching the affected site may cause spread of the oily substance (urushiol) to other body areas, resulting in a larger area to be affected
• Formation of red skin rashes that present burning, irritation, and pain
• The skin rashes are striated or striped in pattern
• If exposure to the white sap is present, it oxidizes to black in spots or stripes. The reaction can be more severe at these sites
• Over time, the rashes may become fluid-filled blisters; some blisters can be large
• The rashes form only at the sites of exposure to the plant; the rashes do not spread, even if the blisters break
• Eating the plant parts can result in swollen mouth, and injury to the throat, esophagus, stomach, and perianal skin
• Inhaling smoke from burning poison plants can result in chest pain/tightness and severe respiratory difficulties. Also, the eyes frequently swell shut. In some individuals, this can be life-threatening

Generally, not all episodes of allergy will be of the same severity. In some individuals, the most severe symptom caused by certain Poison Plant Allergies is anaphylaxis.

• Anaphylaxis (sometimes called an anaphylactic shock) is a life-threatening, whole-body allergic reaction
• During anaphylaxis, tissues in various body parts release histamine and other messenger chemicals, which causes swelling of the throat and other symptoms
• Swelling of the throat is especially dangerous as this can cause shortness of breath. If the swelling is not reduced soon, then there is a possibility that the individual could die from a lack of sufficient oxygen
• It can also result in a bluish skin, weak pulse, and decreased blood pressure (hypotension)

How is Poison Plant Allergy Diagnosed?

The diagnosis of Poison Plant Allergy may involve the following:

• Physical examination, assessment of presenting symptoms, and medical history evaluation
• No other specific tests are generally necessary

However, if required, the following tests may be conducted:

• Radioallergosorbent (RAS) test; to determine the specific allergy-causing substance
• Skin-prick test: This is a reliable test only for penicillin, and not for many other drugs
  • For this test, tiny amounts of certain substances are injected right underneath the skin (forearm, upper arm, or back)
  • After 15-20 minutes, if the spot where the chemical was injected swells, or if there is redness noticed, then this indicates that the individual may be allergic to the substance
• Blood test to detect antibodies (antibody test)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Poison Plant Allergy?

The complication of Poison Plant Allergy is associated with the allergic reaction itself and it depends on the severity of the reaction. It may include:

• Anaphylactic shock/reaction that may be life-threatening
• Having on form of allergy can make the individual prone to other Poison Plant Allergy types
• In severe reactions, a tracheostomy may have to be performed during an emergency situation 

How is Poison Plant Allergy Treated?

The treatment of Poison Plant Allergy may be undertaken in the following manner:

• Washing skin thoroughly with soap and water; changing clothing; using over-the-counter topical applications for skin rashes
• An OTC wash that can remove the oil from skin may be recommended
• Anti-allergic medication for mild reactions; antihistamine therapy, that is prescribed by the allergy physician
• Corticosteroid therapy to reduce inflammation, or administration of NSAIDs (if necessary)
• In the case of anaphylaxis (severe allergic reaction), epinephrine or adrenaline is immediately administered
• Breathing support as necessary, control asthma symptoms and low blood pressure

How can Poison Plant Allergy be Prevented?

It may not be possible to completely prevent Poison Plant Allergy; however, the following factors may be considered:

• Destroying poison plants using suitable weed killers from home gardens or backyards, once the plant has been identified
• Using adequate protective wear (full-sleeved shirt, gloves, goggles) while handling the plant
• Avoiding burning dry leaves or dead poison plants
• Washing hands thoroughly to prevent the toxic compound from spreading to other body areas, or even to clothing and other objects (such as garden tools)
• Cleaning fur of pets that are exposed to the plant
• Avoiding eating wild berries and plants, especially if you have no information about them
• Following working in the garden or fields, hiking, or camping, always wash hands thoroughly, prior to eating anything

An injectable desensitization regimen was available in the US for a number of years. It was discontinued because the data regarding effectiveness was not strong.

In case the child or adult is susceptible to an anaphylactic shock (high-risk individuals) from Poison Plant Allergy, the following should be considered:

• Being watchful of triggers and avoid them
• Wearing medical alert information bracelets
• Carry auto-injector epinephrine or adrenaline medications such as EpiPen, Anapen, or Twinject. Since the condition may recur, it is advised to carry 2 doses (2 pens)
• Supervise children on how to self-administer the injection, if required
• If child is prone to anaphylactic reaction, then information (preferably written instructions) should be given to day care, school authorities accordingly
• Adults should inform their spouses, colleagues, and friends, about the condition, in case of a future emergency

What is the Prognosis of Poison Plant Allergy? (Outcomes/Resolutions)

• The prognosis of Poison Plant Allergy is dependent on the extent of exposure, severity of the symptoms, as well as general health of the patient
• In most cases, the prognosis is good with adequate home care and/or treatment. A complete resolution of the skin rashes usually occurs within 14 to 21 days
• In case of severe allergic symptoms due to severe exposure/poisoning, it may prolong time of recovery. Occasionally, severe poisoning (from inhalation of burnt plant smoke) may result in obstruction of the airways, necessitating immediate medical attention
• In some cases, the allergic reaction may be severe, causing anaphylaxis. This is a medical emergency that can lead to a respiratory failure. It requires an immediate treatment of the condition. In such cases, the prognosis is guarded and it depends on whether immediate medical assistance is provided

Additional and Relevant Useful Information for Poison Plant Allergy:

Please visit our Allergy Health Center for more physician-approved health information:

http://www.dovemed.com/health-topics/allergy-center/