Hello, I'm Dr. Deb.
I recently came online and see that your question hasn't been answered. I'm so sorry that you've had to wait for a response, but if you still need assistance, I'd like to help if I can.
It sounds as if your cat may be suffering from an upper respiratory infection
(URI) or the cat flu which is going to be the most common cause of all the symptoms you mention.
This condition is similar to a cold in humans in that it is usually secondary to viruses: Herpes or Calici viruses are the two most common causes of this condition in a cat.
Secondary bacterial infections can develop (the nasal and/or eye discharge can be green or yellowish in color) and when this happens, antibiotics are usually dispensed.
These episodes typically last anywhere from 10-14 days to give you an idea of the timeline involved.
What you can do for him at home would be to:
1. Use warm water to clean the eyes and nose of any discharge that builds up. Over the counter artificial tears can be used to flush out the eyes if they're involved.
2. Nasal decongestant drops can be helpful although many cats don’t like them very much as you can imagine. The medicated ones (a-c below) should only be used for three days in a row, with one drop in each nostril; otherwise what’s known as a rebound effect may occur. This is one reason why I prefer "d":
a. Pediatric otrivin=0.05% xylometazoline
b. “Little Noses" Decongestant Nose Drops with phenylephrine hydrochloride
c. Afrin (oxymetazoline)
d. "Little Noses" Saline Spray/Drops non medicated which can be used more than three days in a row.
3. You can place him in a bathroom with hot water running so that the steam can loosen up secretions although this may not be necessary if you live where it's humid.
4. Antihistamines can help some cats with this condition. Acceptable ones to use include
Benadryl at a dose of 1/2 of a 25 mg tablet given twice daily or
Chlorpheniramine at a dose of 2-4 mg twice a day or
Claritin at a dose of 2.5-5 mg twice or
Zyrtec 5 mg once or twice a day
It is important to ensure that the formulations used contain ONLY the antihistamine and are not combination products (e.g. Claritin-D contains pseudoephedrine, which could cause very significant adverse effects in a cats.
Sedation is a common side effect with these kinds of drugs.
5. Probiotics such as Forti Flora have been shown to help many of these cats with URI's; probiotics aren’t just useful for gastrointestinal issues. This particular product is available as a powder which is sprinkled on the food
every day and can be purchased at many pet/grain stores or online.
I hope this helps although, again, my apologies for the delayed reply. Deb