Carrots are rich in carotenes, which are substances related to vitamin A. They're found in the orange pigments and are good for you, but, if you eat lots and lots of carrots, you can develop a yellowish or orange cast to your skin. It's mostly noticeable on the soles of your feet and the palms of your hands.
Benadryl is another decongestant safe for use in cats, although it is usually not as effective as chlortrimeton in treating congestion. Benadryl is generally more beneficial with treating snake bites, reactions to vaccinations, itching, and insect bites.
Nasal spray is another decongestant option for your cat. Buy plain saline nasal spray and treat your cat every six to eight hours. This will help to naturally open up the sinuses and can be used on conjunction with other decongestants such as chlortrimeton or Benadryl.