I don't know that it would delay your period. It contains a lot of acetaminophen. Darvocet side effects: Hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects: Shallow breathing, slow heartbeat;feeling light-headed, fainting;confusion, unusual thoughts or behavior;seizure (convulsions); or nausea, stomach pain, loss of appetite, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes). Less serious side effects include: feeling dizzy or drowsy;mild nausea, vomiting, upset stomach, constipation;headache; blurred vision; or dry mouth. Tell your doctor about any unusual or bothersome side effect.
