What is the best way to get rid of phlegm and a stuffy nose?

Blow your nose.: The best way to get rid of this is to blow your nose and get it out. Sometimes your nose can be swollen from the flu, so nasal decongestants and cough medicine may be needed. Allergies can cause this, like hay-fever in the spring and summer, so a Benadryl (diphenhydramine) might help. All these things help depending on why your nose is stuffed.