I accidentally took 800 mg of Ibuprofen today within an hour! I had a bad headache and forgot I took it when the headache didn't go away? Is this bad?

Ibuprofen. 800 mg of ibuprofen three times a day is sometimes prescribed for acute inflammation so it is safe if taken properly. Please do not take it on empty stomach and eat some low calorie food such as crackers every couple of hours. Its effect goes away in about 8-12 hours.