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2025

A Skipping Beat: When Zithromax Caused More Than Stomach Upset

Treating sexually transmitted infections is a significant part of my practice as a urologist. Thankfully, for many common bacterial STIs like Chlamydia, we have highly effective treatments. The single-dose regimen of Azithromycin, often known by its brand name Zithromax, is incredibly convenient. Patients appreciate the simplicity – one dose, taken in the office or right after their visit, and they're done. No need to remember multiple pills over several days. It improves compliance and makes treatment straightforward. But even with medications we use frequently and consider relatively safe, we always have to keep the potential for less common side effects in the back of our minds.

I recently saw a young man, let's call him Kevin, probably in his early twenties. He came in for screening, and his test came back positive for Chlamydia. He was otherwise healthy, no significant medical history, no regular medications. We discussed the diagnosis, contact tracing, and the treatment plan: the standard single 1-gram dose of Azithromycin. I administered it right there in the clinic. We discussed common potential Zithromax side effects – mainly gastrointestinal upset, maybe some nausea or diarrhea – and scheduled a follow-up test to confirm cure in a few weeks. Routine stuff.

So, I was a bit surprised when my office received a call from Kevin just two days later. He wasn't calling about stomach issues, though. He sounded anxious. "Doc," he said, his voice a little shaky, "I don't know if this is related to the medication or what, but yesterday and a bit today, I've been feeling... weird. Like my heart is fluttering, or skipping beats. And I got really lightheaded for a minute when I stood up quickly this morning."

My internal antenna went up immediately. While GI upset is common, cardiac symptoms like palpitations and significant dizziness after Azithromycin are less frequent, but potentially more serious. There's a known, albeit rare, association between Azithromycin (and other macrolide antibiotics) and a condition called QT interval prolongation. Essentially, it's a disturbance in the heart's electrical recharging process between beats, visible on an electrocardiogram (ECG). In susceptible individuals, this prolongation can increase the risk of dangerous arrhythmias, which can certainly cause palpitations or dizziness, and in very rare cases, more severe events.

"Kevin," I said, keeping my voice calm but firm, "thanks for calling. It's important you told me about this. While it could be unrelated, those symptoms – the heart skipping feeling and the lightheadedness – are something we need to take seriously after taking Azithromycin."

He sounded more worried now. "Seriously? Like, dangerous?"

"It's usually transient and the risk is generally very low in young, healthy people," I reassured him, "but we can't ignore the possibility. There's a potential side effect involving the heart's rhythm that can cause symptoms like yours. The safest thing to do is get it checked out quickly."

Given his symptoms, especially the lightheadedness coupled with palpitations, I didn't want to take any chances. "I strongly recommend you head to an urgent care center or the emergency department right now," I advised. "They can do an ECG to check your heart rhythm and make sure everything is okay. Let them know you recently took a single large dose of Azithromycin and are experiencing palpitations and dizziness."

I could hear the hesitation, perhaps thinking it was an overreaction. "Is it really that urgent?"

"Yes," I affirmed. "While the odds are very high that it's nothing serious or will resolve on its own, we need to rule out that small possibility of a significant heart rhythm issue. It's always better to be safe."

He agreed to go. I later followed up – his ECG, thankfully, was normal by the time he was evaluated, and his symptoms had subsided. It was likely a transient effect of the medication. But the episode was a stark reminder. Convenience is great, and common side effects are manageable, but as physicians, we must remain vigilant for those rarer, potentially more harmful adverse events. Listening to the patient, recognizing the potential significance of less common symptoms, and acting cautiously are paramount, even with medications we use every day. That single dose might be simple for the patient, but our responsibility for their safety extends beyond just handing them the pill.

by Dr. Gregory J. Lowe on 2025-05-01 04:08:46