Took 600mg of ibuprofen. now i'm feeling jittery...heart racing..and anxious. is this common?

No, but reported: Though rare, side effects like palpitation( heart racing), anxiety, seizures/tremors have been reported with Ibuprofen (motrin, advil) . These risks may increase with increased dosages/duration of use (caution with heart disease). Drink plenty of water, usually this is out of the system in about 24 hours after the last dose. If these symptoms persist see your physician for evaluation and care.