Colds in kittens are usually caused by a virus. Calicivirus and Feline Herpes Virus 1 are usually the culprits. The most common clinical signs are sneezing, runny eyes, loss of appetite and a runny nose. Ulcers on the nose and lips are also seen with calicivirus. These symptoms last 7 – 10 days. Sometimes, the ocular discharge is so bad that it actually glues the eyelids together. Without treatment, the eye might rupture leaving the kitten blind.
The good news is that it is easy to prevent viral infections with a few precautions. First, vaccinate the queen before she becomes pregnant and immunity will pass from her to the kittens through her milk. Second, vaccinate kittens against these viruses. Depending upon the situation, I start kittens on their boosters at 6-8 weeks. Third, do not expose kittens to other cats until they have received all of their boosters. Wash hands thoroughly before working with young kittens and make sure you are wearing clean clothes. When I raise orphan kittens, I wash my hands for ten minutes and put on a protective gown before working with them.
Here is a link to a video I did for eHow.com on this topic.