After a typical head cold lasting 1-2 weeks runs its course, why is it
that occasionally the nasal irritation (runny nose) continues on for
1-2 months.  I can think of 3 possibilities: the immune system takes a
very long time to completely kill off some cold viruses, the immune
system sometimes remains active long after the virus is gone, or the
nasal passages are particularly sensitive to normal everyday
pollutants after prolonged irritation from  the cold.  Any of these on
the right track?  (ps: I'm not talking about secondary infections,
etc.) Thanks for any insights... Dave

Aha ... That's exactly what happened to me FOUR YEARS ago and it's still with me!

Eventually, the doc peeped up my nose and detected a noseful of polyps.

The surgeon later chopped out all the polyps but still no cure.

Swabs show no infection and yet the non-infection is always cleared up
temporarily by antibiotics.

Now trying homeopathic remedies and (fingers crossed) these do seem to be working.

Of course, you may not necessarily have the same problem.

I shall now ask crabcakes (who's a real wiz) to have a go at
explaining my phenomenon.

Zinc Tablets, that'll stop it.  I discovered quite by accident, and it
knocks out all symptoms of a cold in 2 days. The tabs each are 333% of
the RDA, I take three at a time.

you could have a mild allergie, i've got hayfever, and it's a b***h,
it's starting up again now coz it's only grass pollen that gets me.