Morphine is an opioid and natural opiate. It is generally regarded as the gold standard of opioids as it was the first substance to be isolated from opium. It is used to treat moderate to moderately-severe pain. It is generally administered intravenously in liquid form, but it is also available in pill form. Tolerance develops rapidly, though once patients are properly titrated to the required dose, adjustments are rarely needed. It's primary side effects are drowsiness and nausea, although in many patients it can cause insomnia, hallucinations and nightmares.