As my mom's (91) POA, can I refuse a physician's prescription order if I feel it's not in mom's best interest?

Imho, I do not advocate that you decide what medication(s) that your mother should be taking since you are not a medical doctor. I suggest that you speak to your mother's physician and not a psychologist, who does NOT prescribe medications, regarding your concerns. While you could, for all intents and purposes, ask the pharmacist not to fill the rx, what is going to happen when your mother's physician asks how she is doing on the medication if YOU decided not to receive the medication? Bottom line is that you speak to the prescribing physician with your valid concerns. Again, psychologists do not prescribe medications.

I said, "Yes," but I feel I must explain in more detail. As your mom's medical POA, you are entrusted with her medical care decisions: medications, treatments, doctor's appointments, hospitalizations.... Your duty is to act on your mom's behalf in accordance with what you know to be her expressed wishes. So in that sense, you can decide not to fill a prescription.

Before you go that route, there are a few things to consider. If your mother is in constant pain and anxiety, she obviously needs relief. She should have a doctor who is managing her pain. Her anxiety is appropriately managed by a psychiatrist. Since the SSRI is being prescribed by a psychiatrist, you need to talk to this doctor. Ask the reasons for giving your mother this medication and the expected outcomes. Ask about side effects (your main concern) and how they would be addressed. Ask if there are other medications that could be considered instead of the medication in question and their benefits and problems (every drug has side effects). You may find that this medication may be the most reasonable one to try to help your mother's intractable anxiety.

The short answer here is Yes.

What do you think would be better than the experts suggest
Sometimes it is better not to read up on side effects and then expect them

My mother was prescribed an SSRI late in life (90s) and is doing well on them, with minimal, if any, negative effects. The side effects described are detailed and the drug companies must reveal them to avoid lawsuits. People often have a more jaundiced view of medications for mental health than they do for other physical reasons. Would you be as hesitant to offer your mother a prescription for a medication for diabetes or liver or heart function, though all these come with negative side effects? Anyway, the short answer is as her healthcare proxy you are able to make medical decisions for her....but I would speak with her doctor about the risk v. benefit of an SSRI. If they can help with anxiety or depression, why not allow them to help her?

I would say yes, as I have had to make a decsion with my brother being the POA. I ask the primary doctor to do an assessment on his medications and see what meds he's taking and what meds is not necessary. We found out he was taking several medicines for the same problem and it had to narrowed down to him taking only a few. What happened is that the primary doctor he was seeing, and his other doctors he sees, there was no collaboration between them on his meds, so I was the watch dog. once the primary doctor reviewed his medicine intake, his meds were changed drastically. He felt so much better. While my brother was in assitant living I usually did a check up to see what meds they were giving him. They really don't have the right to change his meds or give new meds, at all unless they get a signed consent from you and your mother to sign. Those places are not good for medication management when it comes to prescribing any medication for the resident, only their doctor. You have that right also to make a call to stop medicine you feel will harm your mom or make matters worst. Any change in her medication tthey must notify you for approval.

I have attended every medical appointment with my mom (90) for 5 years. I am in the room with her geriatrician, and am consulted at the time when a new Rx is suggested - before it is prescribed.

Over the years, my mom has gone on 1 long-term medication - which we tried increasing, briefly, with negative side effects - and the occasional short-term Rx (such as an antibiotic). With every medication my mom and I have been intricately involved in the discussion with the doctor. And, when we did stop the trial increase, I called the Dr's office to report returning to the former level of the drug.

Personally, I would not simply call the pharmacist to stop a Rx from being filled. It strikes me that a conversation with the Dr is in order so that your mom gets the relief she needs with the intervention that is right for her. IMO, simply stopping the one medication is not serving the full roll as POA because you haven't addressed the symptoms - just rejected a medication.

I recently had my mom(79) taken off of three meds and within 24 hours she was making remarkable strides with her cognition. There was a series called “Awakening from Alzheimer’s” where the first episode was about brain fog and meds. I requested moms med list, met with the DON, and it’s done wonders.

Many drugs treat various symptoms.

I would discuss the purpose of this drug with her doctor.

It could very well help your mom. Of course, some people experience side effects but not everyone does, plus you have to look at if the benefits outweigh certain side effects.

Dosages can be modified specifically for your mom or another drug can be substituted.

Best wishes to you and your mom.