Duplication or reproduction of existing classified information is not derivative classification. Persons who apply classification markings derived from source material or as directed by a classification guide need not possess original classification authority. (b) Responsibility.
According to my doctor, 4 hours. You can switch them up. Take acetaminophen, (Tylenol), then wait 4 hours and take Ibuprofen, wait another 4 hours and take acetaminophen and so on. :) 15 people found this useful.
How long after taking Tylenol should you wait before taking ibuprofen?   Tylenol and Ibuprofen are two different classifications of drugs. They may be taken together. For prolonged pain/fever relief, the best way is to take the Tylenol and thâ¦en two hours later take the Ibuprofen.