If you only have one spot, rather than a regular spread of acne, I've read that a dab of white toothpaste can help. Tea tree oil might help, too. If it's a serious problem, go to your GP as Sqad said. They can prescribe a really helpful cream.
one angry red pimple and you would go to doctors - please Sqad - do doctors have not more serious things to do than worry about a pimple that will go away with a little otc treatment. Best make a paste of baking soda - inflammation will go down.
Oh! dear......I have clearly given the wrong advice here, but the OP's heading was ACNE and not just one "angry red pimple".......or just i have taken that literally?
O.K then ignore my advice and stick to topical medicants in this case.