DEAR DR. ROACH: Several months ago, I was just relaxing, watching a movie at home, when suddenly I got a tremendous pain in my inner left thigh. I tried to walk, thinking it was a bad cramp, but the pain was so intense that I almost passed out. This lasted for only a few minutes (but it felt like an hour). The next day, the area was very sore and tender to the touch. By afternoon, discoloration had begun. I saw my physician two days later, and by that time it had a bruise larger than my hand. I was immediately directed to a radiology center, where they determined that there were no blood clots. My doctor advised that, apparently, a blood vessel had burst. I am wondering how common this is, and if I should expect a recurrence? I would not wish such pain on anyone! — Anon.

ANSWER: I see this occasionally. It’s possible that the initial pain was the blood vessel, but I suspect that the muscle cramp came first, and the muscle fibers pulled so hard that they literally tore the tissue, allowing for bleeding into the muscle. Bleeding into a muscle can be very painful, but the blood will eventually find its way out of the muscle, at which point it will show up as a bruise. I suspect that the damage was somewhat higher on the leg than where the bruise was initially, as gravity pulls the blood downward. The bruise will gradually change colors (from dark red to green to yellow to brown) as the blood is digested and absorbed by the tissue macrophages (cells that eat what doesn’t belong).

I seldom see recurrences of this. Stretching and regular exercise are the best ways to prevent severe muscle cramps.

DEAR DR. ROACH: I have been on Valtrex to prevent outbreaks of genital herpes. I went to get the shingles vaccine, but they told me that the Valtrex would kill the vaccine immediately. They wanted me to stay off the Valtrex for at least three months and then get the vaccine; I couldn’t take that chance, for fear of a herpes outbreak. My own doctor told me I need only three weeks, but I still didn’t get the vaccine. I know the vaccine will not prevent shingles, but it would make it less severe. What do you recommend? — C.B.V.

ANSWER: The shingles vaccine contains a weakened form of the varicella-zoster virus, which causes both chickenpox and its recurrence, shingles. Acyclovir and the related drugs valacyclovir (Valtrex) and famciclovir (Famvir) prevent the virus from replicating, and are likely to render the vaccine ineffective. According to the Centers for Disease Control and Prevention, these drugs should not be taken for 24 hours before the vaccine or for two weeks afterward. I would recommend getting the shingles vaccine, as an outbreak of genital herpes is unlikely in that short period of time for most people. Plus, the reduction in risk of getting shingles in the first place (it does have some benefit) and the reduction in severity, but also — and most importantly — the reduction in the risk of painful neuropathy after shingles is worth this risk of an outbreak, in my opinion.

DEAR DR. ROACH: Can a smoker donate blood in the U.S.? In my country, those who smoke more than three cigarettes per day cannot donate blood. — A.T.

ANSWER: Yes, in the U.S. and Canada, most blood banks, such as the American Red Cross, allow smokers to donate blood. The full list of eligibility criteria can be found at tinyurl.com/blood-donation-criteria.

DEAR DR. ROACH: I am a 69-year-old female breast cancer survivor. I’ve been taking Arimidex for five years, and plan to continue for another five. Through the years, my bone density scans have been normal, up until this year. I’m now on the edge of osteopenia. My oncologist now recommends Prolia. After reading about the possible side effects, I am very hesitant to receive the injection. I feel like, at this point in life, I should just take my chances on the possibility of breaking a bone rather than expose myself to potential harm from Prolia. I’ve started daily vitamin D as well as increased calcium intake from food, rather than supplements.

What are your thoughts on this drug? — C.R.

ANSWER: Anastrozole (Arimidex) is an aromatase inhibitor (AI): It works by preventing the body from converting androgens from the adrenal glands to estrogens, which are female hormones that encourage some breast cancers to grow. However, estrogens also help keep bones strong, so it is common for post-menopausal women on anastrozole to develop bone loss leading eventually to osteopenia and finally to osteoporosis. AIs like anastrozole increase the risk for hip fracture. A hip fracture is a major health risk: One-year mortality rates after hip fracture range from 14 percent to 58 percent. Preventing a hip fracture is critically important.

In osteoporosis, treatment with denusomab (Prolia) or bisphosphonates generally has more benefits than risks. I normally recommend against the use of these drugs in women with osteopenia; however, in women taking anastrozole, it is reasonable to consider the use of denosumab or a bisphosphonate in women with severe osteopenia or in those in whom the bone density is dropping rapidly. It doesn’t sound like that is the case in you. However, you may have more risk factors for fracture than I know of, which may be why your oncologist is recommending treatment.