Pain pills are a common form of medication used to relieve pain. There are many different types of pain pills, and they can vary in how long they stay in your system. Pain pills typically remain in your system for one to four hours. However, this can vary depending on the type of pill, your body weight, and other factors. If you take a pain pill that contains acetaminophen, it may stay in your system for up to eight hours. Pain pills that contain ibuprofen may stay in your system for up to 12 hours. If you take a pain pill that contains codeine, it may stay in your system for up to 24 hours. The half-life of a pain pill is the amount of time it takes for the level of the drug in your body to be reduced by half. For most pain pills, the half-life is between two and four hours. This means that if you take a 100mg pill, after four hours there will only be 50mg of the drug in your system. After eight hours, there will only be 25mg of the drug in your system. And after 12 hours, there will only be 12.5mg of the drug in your system. Ultimately, how long a pain pill stays in your system depends on several factors. If you are concerned about how long a pain pill will stay in your system, speak to a doctor or pharmacist.