this is typically a problem called keratosis pilaris. this is a genetic problem that we see in people. it can just happen. sometimes you grow into it sometimes you grow out of it. but also i tend to see it in people who have either personal or family histories of asthma or allergies. it's not something that we can cure but we can help control it. using products like urea or lactic acid or exfoliants this can help smooth the skin and make it softer. so scratching and picking at it obviously will make it worse and will make it more red will make it likely to last longer. scrubs can help to some effect. retinoids have not been very effective for this but using products that are called keratolytics; something that will help the skin cells turn over more effectively can help it dramatically. for some people it's worse in the summer for some it's worse in the winter. you can sort of pick your season. if you are out in the summer and you have a short sleeve dress it's more important to try to treat it then and in the winter you can let it go if it doesn't bother you. but it's not a harmful condition it's more of a nuisance.
i get bumpy skin on the back of my arms. i have tried microdermabrasion scrubs but they don't wok. what can i do?