OTC Flu Medication: Advice please?

I have the flu. For the past 5-6 days, when I lie down to sleep, about 30 minutes later I wake up with coughing and I cough for the next several freakin' hours. The cough is totally in my throat. Non-productive.
Cough syrup with codeine didn't work.
Is there a difference between Theraflu P.M. and Alka-Seltzer P.M.? If it just has an anti-histamine in it, will that work? Does it have to specify that it works against this damn Post-Nasal Drip?

Thanks for your input. My wife will sleep better too and I'll stop kicking the dog.

If you feel like something is running down the back of your throat and causing you to cough (the post nasal drip) try an antihistamine and a decongestant.
For colds you need the sedating antihistamines (good thing since you're taking it at night. I usually recommend benadryl- 25mg should do the trick, but if not try 50. If you need something for the day, you can try chlortrimeton 4mg- while it is sedating as well, I find it less so than benadryl.
As for the decongestant, pseudoephedrine or the like will dry up the secretions.
You can get these separate medications "over the counter" or in several combination preparations- I suspect theraflu may have them (I apologize, I'm not sure what's in Alkaseltzer PM other than an antacid and something to make you sleepy...)
Good luck!

i advise you to have something containing
BUTAMERATE HCL for your dry cough...try to have some camomile drink form the nature stuff shop.. it is soooo good for your condition, some HONEY would be great too just before go to bed