probly this is advice in the category of "you shouldn't do this, but if it happens anyway, this is something to notice"
i have noticed TWICE in the last 3 months that decongestants have a major and lasting impact on my lymphedema in my surgery area of my neck.
i got a cold in feb which was super bad, and it caused my sinuses and my eustachean tubes to clog completely. i took double doses of cold medecine or decongestants to get to the point of clearing my E tubes so i could hear and be able to feel like i have balance. coincidentally, my lymphedema noticeably shrunk by nearly half.
in the last few days i got another cold, but much less severe. today i took regular doses of generic dayquil. just a few minutes ago i noticed in the mirror (brushing my teeth for the umpteenth time today) that my neck has shrunk by about 15% or so compared to this morning... (yes, i pay that much attention).
so, i am NOT recommending anyone dose themselves on pseudoephedrine or benadryl to shrink the lymphedema (especially considering the fearful reaction your salivary glands may have!), BUT if you do have to take decongestants, notice your lymphedema's reaction, k?