Is taking narcotic painkillers without a medical prescription—whether to relieve pain or treat insomnia—considered a sin and classified as drug addiction? Does it invalidate fasting if taken during the daytime in Ramadan via intravenous injection, and what is the expiation required in this case?

If a person takes a painkiller out of necessity to alleviate pain, there is no blame or sin upon him. As for using painkillers that have an intoxicating effect, such as Pethidine or Morphine, when there is a necessity or need, it is permissible if no other permissible substances are available to alleviate the pain, provided that their use does not result in a greater or equal harm, such as addiction. These painkillers do not affect the validity of the fast if administered intravenously, and there is no need to make up for the days they were used. However, using them for insomnia raises concerns that it might be a symptom of addiction, and what is forbidden must be avoided. Therefore, it is not permissible to use narcotics to combat those symptoms.