Sunburn

My son got a severe sunburn on his lower legs, worse at the back of the knees.  We treated with Dermaplast, pain meds, etc.  Sunburn is gone, still some redness in the area behind the knees.  
My question is, after he takes a shower, the area where he had the sunburn is extremely red and purple, area does not hurt, redness goes away after 20 minutes or so,  but this did not happen until he had this sunburn.  It has been 6 weeks since the sunburn.

Thoughts please?  

Thanks.

[Bhupinder Kaur, MD]

Hello,
This looks like it is case of irritant contact or photodermatitis. Apply cool compresses on the area and ask him to take bath with cool(not very cold) water. Do not scrub the skin or shave the skin and use a soft towel and gently pat your skin dry.Also use a sunburn Over-The-Counter remedy containing aloe vera and a light moisturizer or a dusting powder to relieve chafing.You can apply silver sulfadiazine (1% cream) on the skin except face and see if it helps.If the symptoms still persist then you should consult a dermatologist and discuss the option of dermabrasion or laser resurfacing.

I hope that helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.