Hello,
The rash that results from the poison plants is a form of allergic contact dermatitis. Symptoms include redness and itching of the skin, development of rash and sometimes development of blisters from rash.
Once it begins, the rash will usually clear on its own by 14-21 days. Treatment is directed at controlling the itching. You may take oral antihistaminics like benadryl or zyrtec.Also apply calamine lotion as it has a soothing effect on the skin. You can apply OTC steroid cream but it is only helpful if applied right away, before blisters appear, or much later, when the blisters have dried up. Compresses with cool water or Burrow’s solution (available without prescription) can help dry the ooze faster.
Severe cases like extensive blistering and when rashes are present on the face may need oral steroids. But they are available only on prescription. So if the symptoms become severe then pls consult a dermatologist.
Hope it helps.Take care and pls do keep me posted on how your son is doing or if you have any additional queries.Warm regards.
Wet compress with water body temp, put a cloth dip in water wring it and apply on leision.Do every 15 minutes for 4 times then apply calamine.Antihistamine at bedtime.Severe cases need steroids.