How fast does scarlet fever affect you?

The symptoms of scarlet fever usually develop within 1 to 4 days after exposure to the bacteria that causes the infection. The first symptoms are usually a sore throat, headache, and fever. The rash typically develops 12 to 48 hours after the onset of symptoms. It starts as small, red bumps on the chest and stomach, and then spreads to the rest of the body. The rash can last for up to 7 days.