Poison sumac is a type of plant that can cause an allergic skin reaction, such as a rash. There are a variety of over-the-counter (OTC) treatments available for relieving symptoms.

Poison sumac, poison ivy, and poison oak plants occupy numerous outdoor areas. Coming into contact with any of these plants can cause an allergic skin reaction.

These reactions are usually mild and do not require treatment. In some cases, however, blisters from the reaction can become infected and require antibiotic treatment.

Read on for some tips on how to identify poison sumac, how to treat a skin reaction, and when to contact a doctor.

A sumac plant is a type of small tree or shrub with compound leaves, milky sap, and fleshy fruit.

Poison sumac, or Toxicodendron vernix, is more closely related to poison ivy and poison oak than other sumac plants. However, poison sumac is less common than poison ivy and poison oak.

Poison sumac grows mostly on the eastern side of the United States. The plants tend to grow in wet areas, such as swamps.

They are usually around 5–20 feet tall. The leaves consist of seven to 13 leaflets, in pairs, with a single leaf at the end. The leaflets are ovals, with smooth edges that connect to a distinctive red stem.

If anything makes direct contact with the poison sumac plant, it releases an urushiol oil. This oil can reach the skin indirectly, such as by touching contaminated clothing. Coming into contact with urushiol causes contact dermatitis, which is a type of allergic skin reaction.

Symptoms of an allergic skin reaction to poison sumac include:

  • a rash, usually within a few days of contact
  • itching
  • swelling
  • patches, bumps, or fluid-filled blisters

Rashes from poison sumac can range from mild to severe, and they can last for 2–5 weeks.

The fluid from a blister is not contagious, but oil from the plant is. Blisters can also become infected. Some signs of an infected blister include:

  • worsening redness around the blister
  • increasing pain from the blister over time
  • swelling of the blister
  • fluid or pus coming from the blister
  • a yellow crust around the area

In most cases, a rash from the poison sumac plant is treatable at home.

The oils can stick to the skin and fingernails quickly. First, use soap and water to wash any areas of the body that made contact with the plant. Make sure to wash underneath the fingernails.

It is also necessary to wash all clothing or other items that made contact with the plant. Use commercial detergents or specialized poison plant washes with plenty of water.

OTC treatments can provide pain relief from the rash. For example, apply a cream that contains zinc oxide or zinc acetate directly to the rash. Hydrocortisone cream or a baking soda paste might also help. However, avoid applying these creams and pastes to any open blisters.

Oral antihistamines, such as diphenhydramine, can relieve itching.

If a blister becomes infected, use a soft dressing to protect the wound. It is usually best to avoid popping any blisters, as this increases the risk of infection.

A doctor may prescribe antibiotics to treat an infected blister. The antibiotic could be in the form of a tablet or a cream. It is important to seek medical attention for an infected blister to prevent complications, such as cellulitis.

To reduce the risk of coming into contact with poison sumac, a person can try:

  • covering the skin as much as possible while outdoors
  • washing any clothing that may have come into contact with poison sumac, multiple times and in a separate wash to other clothes
  • cleaning all tools with rubbing alcohol or soap and water regularly
  • using barrier skin creams, such as lotions with bentoquatam
  • never burning plants that may contain poison sumac, as the smoke can also cause allergic reactions

Rashes from poison sumac will usually go away on their own with home treatments.

However, a person should contact a doctor if the rash is widespread over the body or occurs on the face or genitals. It is also important to see a doctor for any symptoms of infection.

It is essential to contact the emergency services if any severe symptoms occur, such as trouble breathing or throat swelling. These symptoms can become life threatening.

It is possible to come into contact with poison sumac when outdoors, particularly in wet areas. A person can reduce the risk of coming into contact with poison sumac by covering all areas of skin as much as possible.

The oil from poison sumac can cling to the skin and fingernails. Contact with these oils can produce a skin reaction within a few days. The rash may be red and itchy, and it may contain fluid-filled blisters.

A person can usually treat these symptoms at home using OTC medications. Contact a doctor for rashes that become widespread or infected.

It is vital to seek emergency care for severe symptoms, such as difficulty breathing or swelling in the throat, as these can become life threatening very quickly.