There are lots of things that you can take when you are BF, despite labels telling you not to- this is because they haven't been 'properly' tested and licensed, not because it's not safe to take them. Don't just take stull willy-nilly though, make sure you get some information from reliable resources if you're not sure. BFN have a great specialist phone line.
Decongestants are generally a no-go as they can reduce milk supply. Lots of other things are OK. I've learnt a lot this week through having flu, have spent many hours in front of the open bathroom cabinet, hammering away at my lactmed app hoping it would say yes
Anyway, there's some great info from the BFN here and you can have a look at lactmed online here
ive got an awful cold, been in hosp with 10wk dd, and dh brought me the weakest sudafed possible, said he asked at the counter and that is all i cn take! there must be something stronger i can take! ive got blocked sinuses and ears, blocked nose, sore throat. im taking paracetamol too. its not touchng it- feel like crap.