Skin allergy and the offending agent (allergen)

A few weeks ago I stayed at a relative's house when one evening her elder boy of seven complained of generalised itchiness over his extremities and trunk with face-sparing. I took one look and diagnosed it as an allergic reaction. So we looked at what kind of food/medication he had been taking. The mother attributed the rashes to heat as the weather had been  unusually warm with hardly any rain. I did ask weather the mother had used a different clothes detergent but did not get a specific answer. Anyway we applied calamine cream over his body for relief.

The following evening he suffered the same problem and again we applied the cream. I then went off to stay in my new house the following evening when my relative rang up and told me her 17-month old baby was also  experiencing the same rashes and was extremely  irritable. I asked her to take off his pampers and see whether the part of the body was also affected, if not then it has to be the clothes detergent then she finally admitted that she had just changed the brand of her detergent. Yes, the area covered by pampers was unaffected. I told her to use clothings not washed by the new detergent and see how things were.

In fact my relative, out of fear had gone to see a doctor who diagnosed the condition as some kind of viral infection! The good doctor was going to give medication and an injection when I told my relative to hold on and use only calamine lotion and monitor her child's condition.

She rummaged through her cupboard for clothings not washed by the new detergent and put on her kids and within 48 hours the rashes subsided. So as his elder brother's rashes. The little boy was once again his normal self who usually  responded to a question of "Are you okay?" with the letter "K".

It is only a conjecture but I feel that clothes washed in  an automatic machine somehow are not well-rinsed as a result traces of detergent still stick to the fabrics and this chemical get into contact with the skin of susceptible individuals and cause what we call "type IV delayed  hypersensitivity reaction" causing the itchy rashes. To cure it just get rid of the offending agent.

A good clinical history will preclude the use of unnecessary medications and possible adverse reactions.