My kitten is only about 10–20 days old, but it has yellow eye discharge and sneezes—can I apply erythromycin ointment?

Erythromycin ointment is an over-the-counter skin drug and is not advised for use on the eyes. If the cat’s eyes are red and swollen with more yellow discharge, it is usually eye inflammation such as conjunctivitis; rinse the eye corners with saline, then apply pet neomycin eye drops or other anti-inflammatory drops 4–6 times a day.

If sneezing and runny nose appear, it is not only conjunctivitis but possibly a bacterial or viral upper-respiratory infection such as cat flu, mycoplasma, or chlamydia; besides anti-inflammatory eye drops, keep the kitten warm and seek other treatment, and best go to a hospital for pathogen testing and targeted care.