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DEAR DR. ROACH: Five years ago, I was diagnosed with a kidney stone while getting an ultrasound for a different reason. A CT scan was ordered, which showed that I had a conglomerate of small stones within a calyceal diverticulum in the posterior mid-pole of my left kidney. My urologist at the time said it wasn’t in an area that was amenable to shock wave lithotripsy or a stone removal with a scope.
He said that I could have a wire inserted by interventional radiology, then go to the operating room for a stent that would require an overnight hospital stay. He also said that I could do nothing since I didn’t have any symptoms. I chose to do nothing.
I’ve been fine for five years, but now I’m having issues with urinary tract infections (UTIs), which I usually never get. I made an appointment with the urologist, thinking this might have something to do with the stones. What are your thoughts? -- J.R.
ANSWER: If you’re having UTI issues, then it’s very likely that the stones are responsible. The most common pattern with a stone isn’t repeat UTIs with different organisms; it’s the persistence of an infection despite antibiotics that should’ve cleared the infection. Bacteria can live inside the stones or in a biofilm around the stone, which is highly resistant to antibiotics.
Although there are other causes of persistent and recurrent UTIs, it does sound as though your stones may have become symptomatic. I absolutely recommend that you see your urologist to discuss your treatment options. Antibiotics alone generally can’t cure persistent infections that are associated with stones. The stone (or conglomerate of stones in your case) needs to be completely removed.
DEAR DR. ROACH: I’m having a tooth extracted (due to bone loss), and I’m allergic to penicillin. For past dental work that required an antibiotic, my dentist prescribed clindamycin. I had a bad reaction (diarrhea and a rash). I only took it for two days, but the reaction lasted for several more days. Would you advise azithromycin (Zithromax) or something similar? -- A.K.
ANSWER: First, I’d want to be sure that you need antibiotics in the first place. Most people who think they do actually don’t with the new guidelines. Antibiotic prophylaxis is generally recommended for high-risk cardiac conditions (people with a prosthetic valve, a history of a heart valve infection, unrepaired or incompletely repaired congenital heart disease, a ventricular assist device, or a cardiac transplant). It can also be recommended when undergoing procedures that manipulate gingival tissue or perforate oral mucosa, which doesn’t include a simple cleaning.
If you do need antibiotics, then 2,000 mg of cephalexin once is the usual second-line treatment. If a person’s also allergic to cephalosporins, then azithromycin is a third-line treatment. Most people with penicillin allergies aren’t allergic to cephalosporins, although many automated programs will flag them as allergies.
A mild allergy, such as a rash, needn’t stop a person from getting a cephalosporin. But if there’s a possible life-threatening allergic reaction, such as anaphylaxis or Stevens-Johnson syndrome, then cephalosporins and other related antibiotics should be avoided.
Clindamycin has fallen out of favor due to serious infections (such as Clostridioides difficile) and is no longer recommended by the American Heart Association or the European Society of Cardiology.
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. (c) 2026 North America Syndicate Inc.
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