Plant-induced allergic or irritant skin rashes are very common. There are numerous plants that will cause an irritant reaction in many people and an allergic reaction in sensitive people. In fact, poison ivy, poison oak and poison sumac are the most common causes of allergic reactions in the United States, according to the American Academy of Dermatology.

Skin rashes caused by plants can develop hours or days after contact with the plant, depending on the sensitivity of the person. Redness will develop at the contact site, followed by blisters, and sometimes swelling. A rash can occur anywhere on the body, but may be especially likely on thin skin, such as the face. Plant rashes normally take about 10 days to heal on their own.

The best way to avoid a plant-related skin rash is to avoid the plants that cause reactions. This will require knowledge of the poisonous plants that naturally grow in the region, and the house and garden plants in the area that may cause an allergic or irritant skin reaction.

Skin rashes are often first recognized by the person experiencing symptoms. However, it may be necessary to consult a physician for severe reactions or lasting rashes. If a reaction is allergic in nature, physicians may perform allergy tests to identify the specific allergen (substances that trigger an exaggerated immune system response) causing symptoms. Anyone experiencing a severe allergic reaction (anaphylactic shock) characterized by swelling and difficulty breathing should seek immediate medical treatment.

Skin exposed to a questionable plant ideally should be washed with water immediately after contact. Washing with soap and water within 30 minutes of contact may still help prevent a rash from developing or spreading. Soap and water can also be used on clothing, shoes, pets or tools that came into contact with the plant. Lotions, such as calamine lotion, and cool oatmeal baths can be used to soothe the irritated skin.

Physicians may recommend one or more medications to help relieve symptoms. Corticosteroid creams may be recommended to reduce swelling, redness and itching. In severe cases, corticosteroids may have to be given internally. Antihistamines may be necessary for allergic reactions. If an infection develops in the rash, antibiotics may be necessary to treat the infection.

The primary method of preventing plant rashes is to avoid the plant that triggers reactions. However, it is not always possible for people to know when they are likely to come into contact with problems plants. Protective clothing (e.g. gloves, long sleeve shirts) is essential. Barrier creams that prevent skin exposure to irritants or allergens may also be helpful for some people.