Dear Dr. Roach: I am a 73-year-old man who has recently been diagnosed with moderate-to-severe arthritis in my right knee. I am trying to figure out a healthy way to manage my chronic knee pain. Is there any danger in the long-term use of acetaminophen? I take an anticoagulant (5 mg of apixaban daily), so I don’t take any NSAID pain relievers. I would like to take two 500-mg pills of acetaminophen once or twice a day.

— P.D.

Answer: There is at least one long-term danger I know from the long-term use of acetaminophen (Tylenol), and it is kidney disease. Several studies have shown an increased risk of chronic kidney disease in long-term users of acetaminophen after many years. It’s estimated that 2-4 kilograms of acetaminophen needs to be taken over a lifetime to get double the risk of chronic kidney disease, which is about 5,000 tablets, or about four a day for eight years. Other studies didn’t show significant kidney harm from the long-term use of acetaminophen.

One condition associated with daily painkiller use is called a “medication overuse headache.” This is usually a daily headache (at least 15 times per month) that occurs in people who are already susceptible to headaches (especially migraines) when they take regular painkillers of any kind, whether they’re over-the-counter or prescription. Stopping the medicine usually stops the headaches. I see this condition most commonly with medicines containing opiates and barbiturates, especially Fiorinal or Fioricet.

In my opinion, daily users of pain relievers should at least get yearly checks on their kidney function.

Dear Dr. Roach: I’m a 70-year-old woman in fairly good health. I do water aerobics every day for an hour and lift weights three times a week.

I was recently diagnosed with osteopenia. I have been reading about vibration plates. The research shows that they can improve bone density, balance and muscle strength, which are goals of mine. However, it seems there may be an increased cardiovascular, cancer and detached-retina risk. Do you have insight into the rewards versus the risks?

— B.S.

Answer: The literature on vibration treatment for osteoporosis is mixed. Some studies showed an increase in bone density (in postmenopausal women but not in younger women), although the benefit was small. Most studies showed an improvement in balance with less likelihood of falls.

Most of the studies do not report harms. However, fracture (especially in those with osteoporosis) is possible, and I also read about concerns for cataract and lens detachment after cataract surgery. I did not find reliable evidence linking vibration to cancer or heart disease. Most studies suggest that low-intensity vibration might have a better balance when it comes to the benefits and harms. But as of now, I can’t say that the overall benefit has been proven.

In addition to exercise, you will want to have adequate dietary calcium intake, make sure that your vitamin D level is adequate, and be sure that your doctor checks your FRAX score (frax.shef.ac.uk/FRAX/tool.aspx), which is the single most important number to determine whether medication is recommended.

Contact Dr. Roach at ToYourGoodHealth@med.cornell.edu.