Cat sleeping excessively with a cold!

I took my 2.5 year old Gil to the vet 2 days ago for excessive reverse sneezing, open mouth breathing, and a runny nose/eyes. He was so congested that he could not sleep without waking up every 2-3 minutes to gag or cough. His brother had dealt with a cold the week before but got over it within 3-4 days. The vet gave me lysine powder, plus a liquid antibiotic to help Gil along. I've been running steamy showers in the bathroom to help his breathing and doing my best to keep him comfortable. He has only had about half of his doses of antibiotic from the past two days (because it is nearly impossible to administer it to him) and he has been only somewhat interested in his wet food and water, but not much.

His sneezing and sniffling have decreased dramatically! But, I am still worried because today he has done absolutely nothing but sleep. He woke up briefly to sniff the wet food that i put out for him and to take small drink of water, but he has been mostly laying in one spot for the whole day. This is the first day he has slept like this (I noticed his symptoms this past Monday). Am I being dramatic to be worried about his sleeping? Or does this mean that he is just bouncing back? 

Since you're not seeing improvement, I think you're right to be concerned.  I'd get him back to the vet and ask for a different med.  Most likely the vet will want to give a Convenia shot.  Look it up here on the site before making your decision.  Otherwise, ask for pill form that can be given in a pill pocket or bit of cheese or even ground up in wet food.

To help him eat, warm his food up in a water bath for a few minutes. That will help enhance the aroma.  Try baby saline nose drops twice a day to help open up his nasal passages.  We use Little Remedies Little Noses.

When was the last time Gil ate? A couple of years ago my Apollo had a upper respiratory infection (URI) and he slept a lot like you were describing. Apollo prefers to eat dry food so I put dry food on a plate and brought it to him to eat. He would only eat if I brought the food to him. I also kept him drinking water by carrying a bowl of water to him. Have you tried warming up his wet food and bringing it to him? My cat was also under vet care and my vet was fine with him being sleepy as long as he was eating. You do really want to take Gil back to the vet if he is not eating,