According to Hospice, ibuprofen begins to relieve pain one to two hours after it is taken. Its effects usually last for five to 10 hours. Ibuprofen provides the highest level of pain relief if it is taken regularly for two to three days.
Drugs.com explains that ibuprofen is an nonsteroidal anti-inflammatory drug. It is similar to aspirin in its mechanism of action. It relieves pain and inflammation and can reduce fevers. It acts to block the chemicals in the body involved in pain and inflammation. Ibuprofen can cause bleeding of the stomach or intestine. It can also cause strokes and heart attacks.