In general, psychologists do not prescribe medication. Their training typically focuses on behavior, including mental and emotional processes, and they use various forms of psychotherapy to treat mental health issues. However, this is changing in some places.
there are a few U.S. states (like Illinois, Iowa, Louisiana, and New Mexico), as well as the Public Health Service, Indian Health Service, and the U.S. military, that allow appropriately trained psychologists to prescribe medication. This requires additional education and training in psychopharmacology and related areas, often involving a post-doctoral master's degree or similar program and a period of supervised practice.
When psychologists do have prescribing privileges, they can prescribe a range of medications for the treatment of mental health disorders. These might include antidepressants, anxiolytics, mood stabilizers, antipsychotics, and ADHD medications, among others.
The primary reason for allowing psychologists to prescribe medication is to increase access to comprehensive mental health care, particularly in areas where there is a shortage of psychiatrists. Psychiatrists are medical doctors who specialize in mental health, including substance use disorders. They are qualified to assess both the mental and physical aspects of psychological problems and to prescribe medication. But there aren't enough psychiatrists to meet the demand in many areas, particularly rural regions.
It's also worth noting that many people receive prescriptions for psychiatric medication from their primary care physicians or general practitioners, who may or may not have extensive training in mental health treatment.
However, the question of whether psychologists should be allowed to prescribe medications is a topic of ongoing debate in the field, with various professional, practical, and philosophical issues being considered.
As with any healthcare provider, the important thing is that the person prescribing the medication has the appropriate training and expertise, that they consider the whole picture of the person's health and circumstances, and that the person receiving the medication is closely monitored and is also receiving appropriate psychological care.