Hello and welcome to health care magic,
Your friend seems to be having a post nasal drip
and excess mucous production which is sticky. You need to take an ENT consult and start an antihistamine like levocetrizine as soon as possible.
In any case Viagara can also cause this problem but the antihistamine will take care of the same.
You need to also advice him to take steam inhalation which will reduce the thickness of the mucous in any case.
If these do not help then you must get a CT PNS and get back to me or any ENT as soon as possible
Dr Sriram Nathan