Polymyxin B eye drops for bacterial pink eye usually start helping within 1 to 3 days, but the full course often takes about 7 to 10 days. It will not help viral or allergic pink eye, so if symptoms are not improving after a few days, the diagnosis may need to be checked again.

What to expect

  • Mild improvement often shows up in 48 to 72 hours.
  • Redness, discharge, and irritation should gradually lessen over the treatment course.
  • You should still finish the prescribed course even if the eye looks better sooner.

When to get help

  • No improvement after 3 to 4 days.
  • Worsening pain, light sensitivity, vision changes, or swelling.
  • If you think it may be viral or allergic instead of bacterial, since antibiotics won’t help those types.

Practical tip

A common rule of thumb is: some relief in a couple of days, clearer improvement by the end of the week, and full treatment typically around 7 to 10 days.

TL;DR: polymyxin B usually begins working in about 1–3 days for bacterial pink eye, but you generally need to use it for 7–10 days total.