Nizoral shampoo treats the red bumps and white flakes induced by malassezia yeast. Nizoral doesn't treat acne, although both conditions create a similar appearance. The difference is that the red bumps induced by malassezia do not involve comedones, and you'll notice you have a lot of dandruff (previously invisible white flakes) once you start using Nizoral.
The active ingredient in Nozoral is ketoconanzole, which is somewhat effective, but climbazole is more effective as an active ingredient, and I suggest looking for Hegor 150 climbazole shampoo, which is available on eBay. Ketoconazole and climbazole slowly dissolve the fungal cell walls, but the yeast's hyphae stage creates a biofilm that is difficult to dissolve, so the treatment takes several months -- up to a year -- and you need to use antifungal products on a daily basis afterward.
You'll experience what appears to be an initial breakout when you begin to use an antifungal, because the biofilm had previously prevented your immune system from recognizing the fungal invader, until the fungal cells walls start to dissolve. That's why you'll notice more red bumps rather than fewer, when you first begin using an antifungal. Hang in there, and do not be dismayed.