About 10% of codeine is transformed into morphine, which is what relieves the pain, making it effective in the body. Codeine is essentially a prodrug, a molecule that the body's metabolism transforms into the active medicinal molecule. If you ever forgot to take it, you should take it whenever you remember. You should not take another dose at that time if the time for another dose is now, since doing so might result in an overdose. An overdose may result in health issues, so avoid it. Do not take more than what was prescribed for you. Never discontinue taking codeine if you have been doing so for more than a few weeks without first consulting your physician. Your doctor may lower your dose gradually. Withdrawal symptoms may occur if you abruptly discontinue codeine use.