DEAR DR. ROACH: I am a 71-year-old woman with osteoarthritis. I have had several injections of Euflexxa in both knees in the past with excellent results. X-rays last month showed one knee ”still pretty good” and the other ”almost bone on bone but still OK.” So I went ahead with injections in both knees. Although I had no pain with prior injections, this time the pain was excruciating. I lived in packed ice for the first three days! It’s been eight days, but the pain continues, so severe that I am unable to sleep! I am almost unable to walk at times. Do you have any idea what happened? — M.K.

ANSWER: There are several types of treatment for osteoarthritis, the most common form of arthritis. This is the kind seen in older adults and people with a family history. It is associated with previous injury and is more likely in overweight people.

First-line treatment usually consists of exercise and over-the-counter medications such as acetaminophen (Tylenol). Anti-inflammatory medicines are used as first-line or second-line treatment. If symptomatic relief still is inadequate, it’s reasonable to consider injection. I prefer steroid injection, but these don’t work for everyone. My colleagues in orthopedic surgery and rheumatology often do an injection of hyaluronic acid (Euflexxa, Synvisc and others), which acts as a lubricant and a bit of a shock absorber in the joint. Most people tolerate the injection well, although some recent studies have suggested that the injection is not much better than placebo.

What I suspect happened to you is called a postinjection flare. This consists of pain and swelling in the joint. It happens only a small percentage of the time, and although I haven’t personally seen a case, I understand that it sometimes can be quite severe.

A less likely possibility is an infection, so if you have had fever or if the symptoms are getting worse, you should go back to the provider who gave the injection.

DEAR DR. ROACH: What are the statistics on side effects for Viagra? Specifically, any statistics on older fathers using Viagra having autistic offspring? — A.H.

ANSWER: There has been no suggestion that use of sildenafil (Viagra) or similar drugs leads to an increase in any kind of birth defect or autism. However, older fathers do seem to be more likely to have autistic children, perhaps as much as double the relative risk at age 60 compared with age 30. Both very young mothers and older mothers seem to have an increased risk as well, based on a 2015 study. The absolute risk is still small, about 1.2 percent.

Since older men are more likely to use Viagra and similar medications, it may seem there is an association, but it appears to be the man’s age, not the drug, that is responsible.

DEAR DR. ROACH: My husband has diabetes and has lost about 40 pounds in the past few years. Should his medication be adjusted accordingly? He takes 1,000 mg of metformin and 25 units of Lantus a day. — B.B.

ANSWER: Diabetes control almost always changes with weight loss, so yes, the glargine insulin (Lantus) and/or the metformin may need to be changed based on his lab results. We look especially at the hemoglobin A1c level, which reflects average blood sugar over the past two to three months.

If he has been trying to lose that weight through better diet and exercise, then congratulations. But I always get a bit concerned when I hear about unintentional weight loss, although it’s more concerning when it takes place over a short time.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.