Why am I having a brown reddish discharge while on the pill

Wow, not a lot to go on here, so I'll give you some ideas...

If you are just newly on the pill it is caused by a change in hormonal levels

If you have missed a pill or even changed the time you take the pill it would be called breakthrough bleeding. The pill must be taken at the same time every day.

Can you give me a little more info please?