Abscesses typically incised, drained of friction on the skin — the neck, underarm and groin. The exact cause isn’t known. They don’t need to be treated unless they are irritating or if a person wants them gone for cosmetic reasons. I usually treat these i

Dear Dr. Roach: I watch a lot of skin-care videos by dermatologists. Sometimes they will have a patient who has a very infected blackhead, boil or cyst, etc. It seems like the main treatment is oral antibiotics. How come we don’t inject antibiotics into infected areas like this? Why do we take them by mouth or IV? Would they just sit in the tissue and not go where they are supposed to?

N.F.A.

Answer: The definitive treatment for an infection in a closed space (i.e., an abscess, boil or infected cyst) is to incise (cut it open) and drain it. It is effective, and no antibiotics are usually needed. Injecting antibiotics into an abscess or other closed space might work, but it might not. The oxygen and pH are not optimal for antibiotics to work, and antibiotics work best when the patient’s white blood cells come in and finish up the job.

A milder infection can sometimes be treated with oral antibiotics, but serious infections with pus need drainage.

Dear Dr. Roach: Occasionally I get irregular heartbeats. Recently, I purchased a pulse oximeter. When this happened, the meter read my heart rate in the 30s for a few seconds. What does this mean?

Anon.

Answer: The technology of a pulse oximeter is very good for measuring the oxygen level, and pretty good for measuring the heart rate, at least when a person is very still. However, the pulse ox frequently misreads the heart rate, and a few seconds of a heart rate of 30 is much more likely to be a technological error than a problem with your heart. Certainly people can have heart rates that are very slow, and can sometimes need a pacemaker for it, but the pattern of a slow heart rate for just a few seconds is not typical for most people with slow heart rates.

If you remain concerned, an EKG in your doctor’s office may be enough to reassure you and your doctor that everything is fine. With a higher level of concern, your doctor may order a Holter monitor, which provides very detailed monitoring of your heart for 24-48 hours.

Dear Dr. Roach: What causes skin tags? I am a woman in my 80s. In the past few months, I keep finding small skin growths on my body. I went to a local dermatologist, who used a spray solution that stung a little, and said they would fall off. They haven’t changed. What do I do now?

M.R.

Answer: Acrochordons (“skin tags”) are benign outgrowths of normal skin that usually arise at places