For Clinicians | Sinusitis: When Antibiotics Are Necessary

By Dr. Jamie Wilkey, PharmD, Director of Clinical Education
Medically reviewed and edited by Kristen Carpenter, PA-C

Adult sinusitis guidance changed in July 2025, when the AAO-HNSF published its first guideline update since 2015 [AAO-HNSF 2025]. Three changes affect us in the office or at the pharmacy counter: watchful waiting is now the starting point for every uncomplicated case (yep, even once you’ve called it bacterial), amoxicillin with or without clavulanate is first-line on a shorter course, and a patient who isn’t improving gets reassessed sooner. Today we’re covering all three, plus the clause in the watchful-waiting recommendation that assumes your patient can come back.

What changed in the 2025 sinusitis guideline?

For an adult with uncomplicated acute bacterial sinusitis, waiting used to be one of two options. Now it’s where we start [AAO-HNSF 2025]:

• Watchful waiting became the default. Since 2015 we had the option either to offer watchful waiting or prescribe an antibiotic [AAO-HNSF 2015]. The 2025 version axes the “or prescribe”.  Offer watchful waiting without antibiotics, with assurance of follow-up. The fixed day count for when to start one is gone too. How long to wait now depends on when and how the diagnosis was made.
• The course got shorter. Amoxicillin with or without clavulanate stays first-line, for 5 to 7 days in most adults instead of 5 to 10.
• Treatment failure got redefined. It’s now judged against the antibiotic the patient is already taking. If it’s still bacterial, the solution is a different antibiotic.

You’re thinking, ok, but my patient is miserable and wants something today. They feel like it is a waste to leave our appointment without an Rx in-hand.  The guideline did address these folks: pain relievers, intranasal steroids, and saline irrigation are options for viral and bacterial sinusitis alike [AAO-HNSF 2025]. Those are also the three things a pharmacist can point to on the shelf when the patient asks for help with sinusitis.

When does sinusitis need an antibiotic?

Before writing that antibiotic script, check for one of two patterns. Neither changed in 2025 [AAO-HNSF 2025]:

• Symptoms that persist without improvement for at least 10 days after the cold starts.
• Symptoms that get better, then worse again within 10 days. (Double worsening)

Most of these patients never needed an antibiotic. Bacterial infection occurs in only 0.5 to 2 percent of episodes of acute rhinosinusitis, and acute bacterial rhinosinusitis may also be a self-limited disease [IDSA 2012]. It most commonly occurs as a complication of viral infection but can also be associated with rhinitis or other conditions that obstruct the nose or impair local or systemic immune function [SOURCE NEEDED].

Mucus color isn’t on the list. Neither is how miserable the patient looks. Individual symptoms such as purulent nasal discharge or facial pain can’t accurately distinguish bacterial from viral sinusitis. Kristen Carpenter, PA-C, who reviewed this article, put it this way: “Fever and nasal discharge really don’t mean bacterial. Those symptoms can be viral too, so we don’t really give antibiotics just based on those symptoms. Everyone thinks they have a bacterial infection because of these things.” We covered why in our July article on bacterial vs. viral infection, so we won’t re-teach it here.

Where we struggle is applying the criteria. A Mayo Clinic cohort of adult sinusitis visits from early 2024 found that four of every five visits that didn’t meet any guideline criterion still ended with an antibiotic [Hannan 2026]. And the study counted generously: IDSA’s severe-onset pattern qualified too. The strongest predictor of an unneeded script was a patient on day 7, 8, or 9.

And I get it. Patients get so annoyed when we don’t give them that antibiotic right from the beginning. For them, day 8 of being sick feels like forever when you can’t breathe through your nose. Some of us (me, included) were trained on an older rule of thumb that anything past a week was probably bacterial. The 2025 guideline still draws the line at a full 10 days.

Some patients are worth starting earlier, and that comes down to their own history and health status. Kristen has a low threshold for starting antibiotics on the earlier side if the patient:

• Is immunocompromised (diabetes, etc.)
• Smokes
• Has uncontrolled asthma (maybe)
• Has a weird dental or nasal history
• Has had a recent change in atmospheric pressure (e.g., deep sea diving)

“I’m sure there are others,” she says, “but again it would be based on some individual health status.”

Amoxicillin or Augmentin for a sinus infection? (And why not the Z-Pak)

Once a patient meets criteria and an antibiotic is the right call, then focus on amoxicillin or amoxicillin-clavulanate [AAO-HNSF 2025]. Either one is first-line. For a penicillin allergy, IDSA lists doxycycline as an alternative [IDSA 2012].

What we shouldn’t reach for is the Z-Pak. At the office or the pharmacy counter, it’s the antibiotic patients ask for by name, because it’s short, it’s easy, and “it worked last time”. (Or the last sinus infection was viral and got better on its own, Z-Pak or no Z-Pak.) IDSA recommends against macrolides for empiric sinusitis therapy because resistance rates are too high. They’re not alone. TMP-SMX is on the same list for the same reason [IDSA 2012]. Fluoroquinolones carry their own limit: since 2016, FDA has said to reserve them for acute sinusitis when no other option exists [FDA 2016].

A patient who isn’t better, or is worse, after 3 to 5 days on an appropriate antibiotic gets reassessed: confirm it’s still bacterial sinusitis, look for another cause, and check for complications [AAO-HNSF 2025]. If it’s still ABRS, switch the antibiotic. That’s the ideal follow up visit.

When the clinic isn’t reachable

Watchful waiting comes with a condition: assurance of follow-up [AAO-HNSF 2025]. The recheck is the safety net. It catches the patient who crosses into a bacterial pattern and the rare one heading toward a complication.

Most of us read past that clause, because most of our patients can come back. Some can’t, and some can’t get in the first time either. The patient on an international trip, the family at a remote cabin, the town where a storm closes the clinic.

Here’s what makes sinusitis different from strep: the diagnosis rests on the history and the calendar. There’s no rapid test to run, and an uncomplicated case doesn’t need imaging [AAO-HNSF 2025]. So no clinic doesn’t have to mean no clinician. A phone or telehealth visit can apply the same two patterns, at the first visit or the second.

Whichever visit is missing, the counseling has to do its job ahead of time, at the office or the pharmacy counter. In plain words:

• The two patterns: no improvement by day 10, or better and then worse. Either one means it’s time to reach a clinician, by phone or telehealth if that’s what they have.
• The signs that mean go now, wherever they are: swelling around the eye, changes in vision, a severe headache, confusion, a stiff neck, or a high fever that won’t come down [IDSA 2012].

A patient who already has a prescribed antibiotic at home doesn’t get a different standard. It’s for emergency use only, after first seeking help from a qualified healthcare provider, and the two patterns still decide whether it’s needed.

None of this is a reason to start sooner. Distance from a clinic isn’t on Kristen’s list, and the 10-day line holds wherever the patient is.

Holding our own guidance to the update

We’re a family team of medical doctors, PAs, and pharmacists, and we hold our own guidance to the same update. The Jase amoxicillin-clavulanate card reads 5 to 7 days for sinusitis, and it did before the 2025 guideline made that the standard.

The bigger work is the part this guideline hands to a visit the patient may not be able to make. Right now care runs all or none: the patient gets in, or they’re on their own with an internet search bar and a leftover Z-Pak. Appropriate medical preparation is the step between. It’s clinical work done ahead of time. For sinusitis, that work is mostly teaching patients to count the days, and most of them will be better before they reach 10[IDSA 2012]. It’s in no way a replacement for primary care. We’re here for the times when primary care isn’t there, and we’ll keep publishing how we draw these lines so you can check our work.

The bottom line

The 2025 update kept the diagnosis and changed the default: wait first, with follow-up, and keep the course short when an antibiotic is needed. For most patients, the hardest stretch is days 7 through 9, when they’re tired of being sick and we’re tempted to start antibiotics too early.

Sources

1. Payne SC, McKenna M, Buckley J, et al. Clinical Practice Guideline: Adult Sinusitis Update. Otolaryngol Head Neck Surg. 2025;173(Suppl 1):S1-S56. https://doi.org/10.1002/ohn.1344
2. Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, et al. Clinical practice guideline (update): adult sinusitis. Otolaryngol Head Neck Surg. 2015;152(2 Suppl):S1-S39. https://doi.org/10.1177/0194599815572097
3. Arensman Hannan K, Ilges D, Le KT, Cole K, Stevens RW, Jensen K. Ambulatory antibiotic prescribing for acute sinusitis: a multicenter, retrospective cohort study evaluating appropriateness. Antimicrob Steward Healthc Epidemiol. 2026;6(1):e193. https://doi.org/10.1017/ash.2026.10743
4. Chow AW, Benninger MS, Brook I, et al. IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults. Clin Infect Dis. 2012;54(8):e72-e112. https://doi.org/10.1093/cid/cis370
5. U.S. Food and Drug Administration. CIPRO (ciprofloxacin hydrochloride) prescribing information, section 1.12, Acute Sinusitis. Revised July 2016. https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/019537s086lbl.pdf