Norco 7.5-325 mg is a combination of Hydrocodone/acetaminophen taken to treat severe pain. Common side effects may include constipation, dizziness, drowsiness, headache, and stomach pain. Do not drive or do other activities that require alertness or coordination until you know how hydrocodone/acetaminophen affects you. Call your health care provider right away if your pain increases, you feel more sensitive to pain, or develop pain in other areas of the body while taking hydrocodone/acetaminophen.