Hmm...i'm not sure about that... I used to work in pharmacy and the instructions for Benzaclin (benzoyl peroxide+clindamycin) say that it is supposed to be left on the skin overnight. As for the salicylic acid, the product I am using is called 'Clearasil Overnight Acne Defense Gel'..so im pretty sure im supposed to sleep with it on :)
It's safe u use if it's meant for over-night application.. girls in Pakistan have been using benzol peroxide to bleach hair on the face.. and the after-effects are scary!
Leaving either one on u're face for the entire night isn't a great idea!
topical salicylic acid is a BHA.......excellent exfoliater....which penetrates deep down.....It is recomended by dermotologist as an excellent preventive measure for un-complicated acne....
Benzoyl Peroxide is excellent for un-complicated acne as well and has shown very good results in testing.
I use Paula Begouns Line of skin care.....which includes Salicylic Acid and benzoyl Peroxide.
If you don't know who Paul Begoun is...google her...She has done some of the most extensive research in the cosmetic industry and has shed some light on marketing gimics and provided a wealth of knowledge to the average consumer.
My suggestion is...spot treat your pimple with benzoyl peroxide...start of with a lower dose..2.5 %.....and in between apply a BHA lotion at night. this will really help keep the skin clear.
U also will need a good moisturizer as it could be drying.