You should direct questions to the above thread, but this is an easy one; MA, just like the pseudoephedrine it is sometimes made from, is an effective nasal decongestant, MA (and all amphetamines, Benzedrine, racemic amphetamine, was originally a popular nasal decongestant that became popular as a recreational drug leading to it's being banned and scheduled) is even more so; you're not "congested," strictly speaking, all the pleghm already there is just becoming runny coming out.