My 19 month old son was given Omnicef for strep throat. Within a day he broke out in a rash all over his body and his lips were swollen. He also had severe stomach pain. Dr. took him off the drug immediately and told me to give Benedryl. Told us to be prepared to take him to the ER if his swelling continued. He then switched to Zithromax and seems to be doing better but the rash is worse. I will never use this drug again.