Been given erythromycin antibiotics for infection in my saliva glands, seriously painful swollen cheek. how long until i should feel better?

Usually...: You will start to see relief begin in 2-3 days. It will only get better from there. Definitely make sure you have a diagnosis though. Knowing what caused the infection in the first place is imperative to making sure it just doesn't come back after you finish the antibiotic. Lastly, finish all the pills, regardless of how you feel. Very important. All the best to you!

Soon!: Antibiotics usually take anywhere from 2-3 days to start feeling noticeable relief. In some cases, it gets worse before it gets better. As the antibiotic destroys the bacteria, the toxins in the bacteria are released and can cause a minor increase in your symptoms. If you have no change in symptoms after 7 days, return to your physician - you may need to change antibiotics.