Is it permissible to work in a pharmacy that engages in practices such as concealing sought-after medications and selling them only to those holding a "Shifa" card, and altering prescribed medications for patients in order to retain them as customers? And is this permissible if the person cannot find any other work?

A pharmacist is permitted to sell medications to whomever they wish, unless the law obliges them to sell medicine to everyone. Altering prescribed medications for a patient is forbidden if it involves deception or fraud. However, if the alteration is made truthfully and with full disclosure, there is no harm in it. If working in a pharmacy is free from lying and deceit, then there is no harm in continuing, coupled with giving sincere advice. However, if the work necessitates falling into forbidden acts, then it must be abandoned, except in cases of necessity, while seeking a permissible job.