Codeine is an ingredient found in many common painkillers and cough syrups. Codeine is actually similar to morphine in that both are opiates (i.e. derived from opium). Users become addicted to codeine because it produces pleasant side effects like sleepiness and mild euphoria. Tolerance to codeine tends to build quickly which means addicts have to start taking quite large quantities in order to feel the same sort of effects. Taking codeine normally according to medical instructions is perfectly safe, however taking large or frequent doses causes increasing risk of severe side effects such as nausea, constipation, breathing problems and seizures. When combined with alcohol or other drugs a codeine addiction can rapidly lead to death.