Acne and allergies are two unrelated conditions which can co-exist together.
Allergies can be treated with anti-histamine tablets such as Piriton. These are avilable without prescription but always read the label.
The standard treatment for acne is a course of oral antibiotics such as Oxytetracycline 250mg twice daily and a topical retinoid such as Differin (adapalene). Female acne patients will also benefit from taking an anti-androgen contraceptive pill such as Diane35 or Yasmin. You don't say how old your daughter is, but these birth control pills are commonly prescribed to teenage girls with acne even if they are not sexually active.
Best Wishes, Eloise.
Thanks for the quick response, my daughter is 15. We have tried the birth control pills before, it might be something to look at again. She is on the antibiotics now.
Two of my four children developed acne (the kind that scars). It runs in my family. One was cured with antibiotics almost immediately. It did not help the other.
Hopefully this can help someone else. After posting the above message regarding my 15 year old. We were told that there can be a lot of different stuff triggering my daughters acne, and also found out you can actually have acne with a a type of Roseaca. She is now on Finacea with an antibiotic and her face is clearing pretty quickly.