DEAR DR. ROACH: Does putting Neosporin in your nose protect against colds and flu? – D.L.G.

ANSWER: No. Neosporin is a brand-name combination of antibacterial and antifungal antibiotics, very useful for protecting minor wounds and treating superficial infections, but is not effective against cold viruses or flu viruses. It doesn’t filter out the viruses either, which are really, REALLY small.

Some people have noses that get very dry, even to the point of cracking, which may cause an infection in the nostrils as well as being very uncomfortable. An ointment in the nose acts as a moisture barrier; however, using an antibiotic ointment wouldn’t be my first choice, as the antibiotic is not only unnecessary but can cause an allergic reaction in some people, so plain petrolatum (Vaseline or equivalent) is my recommendation.

DEAR DR. ROACH: My son is 6 years old. He had a high fever and a viral infection two weeks ago. All his test results came back normal. He was dehydrated and was given IV fluids. The next day, he had no fever and no pain. But the day after that, he had extreme pain in the calf muscles of both legs. He got tested again, and his CK level was 1,080. He was tested a few days later and his CK level was 1,600.

What should be my next step? My brother has two sons with muscular dystrophy. Can my son’s situation be connected to it? – M.

ANSWER: I’m sorry. These results are very concerning for your son having muscular dystrophy, and with your family history I’m afraid it’s likely. Your next step should be a visit with a pediatric neurologist, who is likely to recommend genetic testing to see if your son has muscular dystrophy, and if so, which type. The exact diagnosis will guide further evaluation and treatment.

DEAR DR. ROACH: I am taking medication for toenail fungus, and it is working. Is there any worry about being reinfected by bare footwear such as sandals or slippers? If so, can they be treated, or must they be thrown out? – G.M.

ANSWER: The toenail fungus certainly can get into footwear and can be hard to kill. The safest thing is to throw them out and buy new. However, you can try putting anti-fungal powder in your footwear daily. There also are disinfecting devices using ultraviolet light, but it appears there are significant differences among brands.

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 send mail to 628 Virginia Dr., Orlando, FL 32803.