Is a shorter course of antibiotics OK? + Genetic risk of fibromyalgia

September 12, 2026

AI Summary

5 min read

“The longer you’re on an antibiotic, the more selective pressure you put on your microbiome, and therefore the more likely you are to have resistant bacteria.” That’s Dr. Amy Mathers, medical director of antimicrobial stewardship at the University of Virginia, explaining why the old advice to “finish the course” of antibiotics is being reexamined. The episode also covers a new large-scale genetic study on fibromyalgia, which identified 26 genetic variants linked to the condition and points toward nervous system biology as a key driver.

Why shorter antibiotic courses are gaining ground

The long-standing dogma that stopping antibiotics early breeds resistance turns out to be more complicated than once thought. Mathers explains that the real risk of resistance comes from the duration of exposure. Antibiotics don’t just target the infecting bacteria—they also wipe out the healthy flora in your gut. The longer you stay on them, the more you clear out the beneficial, non-resistant bacteria, leaving behind only the resistant organisms. That sets you up for a future infection that may be harder to treat. “The issue is the longer you’re exposed to them, the more you’re getting rid of that healthy flora and selecting for resistant bacteria,” Mathers says.

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What you'll learn

1 (01:38) **The Antibiotic Duration Dogma** - Host Flora Lichtman introduces the long-held belief that you must finish a full course of antibiotics to avoid resistance, and hints that new research suggests the opposite.
2 (03:12) **Why Longer Courses Can Cause More Resistance** - Mathers clarifies the mechanism by which extended antibiotic use actually selects for resistant bacteria.
3 (05:20) **Measuring the "Dose Effect" of Antibiotics** - The discussion turns to how scientists are quantifying the damage done by different antibiotic durations.
4 (06:38) **Finding the Goldilocks Zone for Common Infections** - Mathers cites recent clinical trials that have established shorter, effective courses for many common infections.
5 (07:43) **Are Doctors Up to Date on Shorter Courses?** - The conversation addresses the gap between research and clinical practice.
6 (08:54) **The Psychology of Antibiotic Prescribing** - Mathers explains the non-medical factors that lead to over-prescription.
7 (10:51) **Segment Transition to Fibromyalgia** - The host introduces the second topic: a new large-scale genetic study on fibromyalgia.

+ Full timestamped outline available in the app

Show Notes

You’ve probably been warned that if you don’t finish that course of antibiotics, you could wind up battling antibiotic-resistant bacteria. But a growing body of research suggests that the opposite might be true. What does this mean for you and your next sinus infection? Flora talks with antimicrobial resistance expert Amy Mathers to find out.

Plus, the driver of fibromyalgia, a condition that can cause debilitating chronic pain and brain fog, has been something of a mystery. Patients’ imaging and blood work often turn up normal, and many have felt dismissed by doctors.

A recent large-scale study identified a group of genes associated with the disease, a breakthrough that may help doctors understand people’s risk of developing the condition and reveal something about the nature of this mysterious illness. Flora talks with Nasa Sinnott-Armstrong, one of the study’s lead authors.

Guests:

Dr. Amy Mathers is medical director of antimicrobial stewardship and an associate professor of medicine and pathology at the University of Virginia School of Medicine.

Dr. Nasa Sinnott-Armstrong is an assistant professor of computational biology and public health at Fred Hutch Cancer Center in Washington state.

Transcript will be available after the show airs on sciencefriday.com.

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