For Clinicians | Strep Throat vs. Sore Throat

Do You Need Antibiotics?

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

Most sore throats don’t need an antibiotic. Most of us already know that.

What’s harder to keep straight is the one patient who does, and what happens if that visit gets waved through like all the others. A kid with a sore throat, no cough, tender glands, running a fever, looks almost exactly like the kid down the hall with a garden-variety virus. The difference matters for antibiotic stewardship and, more importantly, for their health. Untreated Group A strep can progress to rheumatic fever: permanent heart valve damage that can show up weeks after the sore throat is long forgotten. Rheumatic fever is rare enough in the US that a lot of us learned about it as a historical disease that isn’t around anymore. But, it isn’t gone. It’s just rare enough, and quiet enough, that it’s easy to lose track of why the testing and treatment ritual around strep exists.

Today we’re talking about the tool that resolves that tension: the Centor score (McIsaac-modified for kids), what it tells you, and why the treatment on the other side of a positive test hasn’t changed in decades.

Do you need antibiotics for a sore throat?

Most of the time, no. The majority of sore throats, especially in adults, are viral. As you know antibiotics don’t affect a virus, and prescribing one anyway doesn’t get the patient better faster. It just adds an unnecessary drug, and an unnecessary risk, to their day. And contributes to antimicrobial resistance.

But roughly 5-15% of adult sore throats, and 20-30% of pediatric cases, are Group A strep. Symptom judgment alone doesn’t reliably separate the two: exudate can show up with mono, fever can show up with either, and “it just looks bad” isn’t a diagnostic criterion. The actual clinical problem isn’t “treat everyone” versus “treat no one.” It’s how to tell, reliably, which patient in front of you is which.

The four-question tool: the Centor score

The Centor score, McIsaac-modified with an age adjustment, turns that judgment call into a short checklist:

• Tonsillar exudate
• Tender anterior cervical lymphadenopathy
• Absence of cough
• History of fever
• Age adjustment: add a point for ages 3-14, subtract a point for ages 45 and up

Add it up. The score runs from -1 to 5, and each end points to a different action. A score of 0 or below means under 10% odds of an actual GAS infection: treat it as viral, skip testing. A score of 4 or 5 means over 50% odds: test to confirm if you want, but treating before the result comes back is reasonable. Everything in between, 1 through 3, is the test-before-you-decide zone, where a rapid strep swab settles it.

Take a 52-year-old with a cough, no exudate, no tender nodes, and no fever: zero criteria met, minus one for age 45 and up, for a total score of -1, the bottom of the range. Skip testing. Now take an 8-year-old with exudate, tender anterior cervical nodes, no cough, and a fever: four criteria met, plus one for age 3-14, for a total score of 5, the top of the range. Test and likely treat.

Using this little checklist in practice cuts unnecessary initial antibiotic prescribing by close to half, without missing the strep infections that matter. It settles the question directly: which patient in front of you actually needs the prescription.

When to test, and when the rapid test needs backup

A score in the test-before-you-decide zone (1 through 3) means swab and run a rapid antigen detection test (RADT). 

• Positive RADT: treat. No backup culture needed, in adults or kids. The test’s specificity is high enough to act on directly.
• Negative RADT in children and adolescents: back it up with a throat culture before ruling out strep. RADT sensitivity isn’t perfect, and this is the population carrying most of the rheumatic fever risk.
• Negative RADT in adults: no backup culture needed. The downstream risk is low enough that a negative result can stand on its own.

In practice, a lot of this happens before you’re even in the room. Plenty of practices swab everyone with a sore throat during rooming now, since newer RADT platforms turn around a result in about 15 minutes, often faster than the visit itself. That’s fine: RADT specificity is high enough that a positive result still means treat, even in a patient who scored a 0 and never should have been swabbed by the letter of the algorithm. The score’s real job in that kind of workflow isn’t gatekeeping who gets tested. It’s telling you how much to trust a negative, and in whom.

Why penicillin, still, after all these years

Once you’ve got a positive result, the treatment hasn’t changed: penicillin V or amoxicillin for a full 10 days. Group A strep has never developed resistance to penicillin. Which is impressive since clinicians have been prescribing it for decades for this. There’s no clinical reason to reach for a macrolide or a cephalosporin here unless the patient has a true penicillin allergy.

The full 10 day course really does matter too. The rheumatic fever prevention data behind this whole guideline was built on the 10-day course, not a shorter one, and stopping early is still the most common way an adequately-treated strep infection turns into a recurrence.

The bottom line

Most sore throats are viral, and most clinicians already know not to reach for the prescription pad on symptoms alone. The Centor score turns that instinct into a number: four questions that tell you which patient is worth testing, and which one just needs reassurance and time. When the test comes back positive, the treatment hasn’t changed in decades: penicillin or amoxicillin for the full 10 days.

We built Jase on that same idea: don’t guess who needs antibiotics, use a real framework to decide. Appropriate medical preparation takes the same logic behind the Centor score, defined criteria instead of a feeling, and applies it earlier: deciding ahead of time which predictable, self-limiting conditions are safe to prepare for before symptoms even start. In no way a replacement for a clinician’s judgment call. Just that same judgment, applied sooner.

Sources

1. Centor RM, Witherspoon JM, Dalton HP, Brody CE, Link K. The Diagnosis of Strep Throat in Adults in the Emergency Room. Medical Decision Making. 1981;1(3):239-246.
2. McIsaac WJ, White D, Tannenbaum D, Low DE. A clinical score to reduce unnecessary antibiotic use in patients with sore throat. CMAJ. 1998;158(1):75-83.
3. Shulman ST, Bisno AL, Clegg HW, et al. Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis: 2012 Update by the Infectious Diseases Society of America. Clinical Infectious Diseases. 2012;55(10):e86-e102.
4. CDC. Clinical Guidance for Group A Streptococcal Pharyngitis.
5. Hamilton JL, McCrea L. Streptococcal Pharyngitis: Rapid Evidence Review. American Family Physician. 2024;109(4):343-349.
6. Gerber MA, Baltimore RS, Eaton CB, et al. Prevention of Rheumatic Fever and Diagnosis and Treatment of Acute Streptococcal Pharyngitis: A Scientific Statement From the American Heart Association. Circulation. 2009;119(11):1541-1551.

For Clinicians | Head Lice Myths

Permethrin Resistance, and What Actually Works Now

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

A few years ago when I was working as a pharmacist a patient handed me a small plastic baggie. I thought it was empty as I was holding it and she asked, “Is this lice?” I turned it over, looking for whatever she wanted me to see. She asked again: “Is this lice??” She’d pulled it from her daughter’s head and needed someone behind a counter to tell her what she was looking at.

I’ve had patients hand me a lot of things over a pharmacy counter. I’d never had someone hand me a baggie of lice and ask me to identify it. Every time lice comes up, I think of that baggie and patient. Patients are asking about this and as we are headed back to school this month it is the perfect time for a lice refresher course for all of us.

Is head lice a sign of a dirty house?

Nope. Lice don’t care how clean the house is, how often the kid showers, or how expensive the shampoo is. If anything, lice attach more easily to clean hair than dirty hair, so the kid who washes every night isn’t safer than the one who skips a day (or three).

They also don’t come from the family dog or cat. Human head lice are species-specific: they feed on human blood and can’t survive on fur. The lice that show up on pets are a different species entirely, and they stay on pets.

The couch, the car seats, the stuffed animals are also fine. Lice survive 24 to 48 hours off a human scalp, so that outdated bagging-everything-in-the-house instinct is solving a problem that doesn’t really exist. Head-to-head contact is how lice spread, almost always. Not shared hats, not the family dog, not the couch cushions.

The house is fine. The nit still in her hair might get her sent home anyway.

What the AAP says about nits and school

Quick refresher, since this is where most of the confusion starts: a nit is the egg, not the bug. It’s glued to a hair shaft close to the scalp and takes roughly a week to hatch. A live louse is the actual insect, crawling and feeding on the scalp. Finding a nit doesn’t mean there’s an active infestation, especially once hair growth has carried it away from the scalp. Most of the panic, and most of the school policy, is built on the wrong half of that distinction.

Plenty of schools still send a kid home for a single nit, or won’t let them back until every last one is combed out. That policy has been out of step with the actual guidance for going on two decades now, and the AAP tightened its language further in 2022.

The AAP’s clinical report states that children shouldn’t be restricted from school attendance over head lice, given how low classroom contagion actually is.¹ It goes further than earlier guidance, too: screening for nits alone isn’t an accurate way to predict which kids are or will become infested, and school nit-checks haven’t been shown to reduce how much lice actually circulates in a school over time.

The distance rule is specific: nits found more than roughly a quarter inch from the scalp are usually already hatched or dead. Diagnosis is supposed to rest on finding a live louse, not counting nits.

Empower a parent who’s arguing with a front office over a nit check with that information, and they have something to bring back to the school.

Why doesn’t permethrin work like it used to?

A parent buys the same box of Nix everyone’s grandmother used, follows the instructions exactly, and the lice are still crawling around seemingly unfazed. In most of the country that’s not user error anymore. Resistance is here!

A 2016 study sampled lice from 138 sites across 48 states and tested them for the genetic marker tied to pyrethroid resistance. The average resistance-allele frequency came back at 98.3 percent, and 42 of the 48 states sampled had populations at 100 percent.² Permethrin resistance isn’t a pocket problem. In most US communities, it’s the baseline.

That marker measures the gene, not the treatment outcome in any one kid’s head, so it’s not a guarantee that a specific box of Nix will fail. But at that frequency, reaching for permethrin as a first-line fix is closer to hoping than treating.

So what actually works?

When first-line permethrin or over-the-counter pyrethrins fail, the next rungs aren’t exotic. They’re underused mostly because parents, and a fair number of clinicians, still think of Nix as the only option.

• Benzyl alcohol 5% lotion (Rx): works by asphyxiating lice rather than poisoning them, so permethrin resistance doesn’t carry over. Two applications, a week apart.
• Malathion 0.5% lotion (Rx): an organophosphate, still effective against most resistant populations. Flammable formulation, so no hair dryers or open flame during application.
• Spinosad 0.9% topical suspension (Rx): kills both lice and eggs, often effective in a single application.
• Ivermectin 0.5% lotion (Rx): a single 10-minute application cleared lice in 74 percent of patients at day 15 in trial, against 18 percent for the vehicle control.³
• Oral ivermectin (Rx): 400 mcg/kg on days 1 and 8 beat malathion lotion for treatment-resistant lice in trial.⁴ No ovicidal action, so the second dose is what catches nymphs that hatch in between. Off-label for lice specifically, and generally avoided under 15 kg over a theoretical CNS risk.

The practical marker for when to move up the ladder instead of reaching for another box of the same product: check 8 to 12 hours after treatment5. A few lice still moving slowly is normal, the medicine just needs time to finish the job. It’s a different story if you don’t find any dead lice at all, or the live ones look just as active as before treatment. That’s the point to switch classes, not double the dose.

A pharmacist can walk a parent through this ladder at the counter faster than most primary care visits allow.

The bottom line

The myths about lice haven’t caught up to the evidence, and neither has the drugstore treatment that used to work. The no-nit exclusion was never real AAP policy. A second failed box of permethrin isn’t bad luck anymore, it’s the baseline. Next time a parent hands you a baggie and asks if it’s lice, you’ve got a straight answer for the house, the school, and the drugstore shelf.

Sources

1. Nolt D, Moore S, Yan AC, Melnick L; American Academy of Pediatrics. Head Lice. Pediatrics. 2022;150(4):e2022059282.
2. Gellatly KJ, et al. Expansion of the Knockdown Resistance Frequency Map for Human Head Lice in the United States Using Quantitative Sequencing. Journal of Medical Entomology. 2016;53(3):653-659.
3. Pariser DM, Meinking TL, Bell M, Ryan WG. Topical 0.5% Ivermectin Lotion for Treatment of Head Lice. New England Journal of Medicine. 2012;367(18):1687-1693.
4. Chosidow O, et al. Oral Ivermectin versus Malathion Lotion for Difficult-to-Treat Head Lice. New England Journal of Medicine. 2010;362(10):896-905.
5. Centers for Disease Control and Prevention. Treatment of Head Lice. cdc.gov/lice/treatment.

For Clinicians | Doxycycline Uses

Lyme Prophylaxis, Malaria Prevention, Acne, and the Doxy-PEP Debate

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

We’re continuing our series on the antibiotics we see most often come up in medical preparation conversations, one drug at a time. This week it is ….drum roll please…..doxycycline’s turn.

Doxycycline is basically the Swiss Army knife of antibiotics, except instead of a bottle opener and tiny scissors, you get malaria prevention and clearer skin. Want stellar proof? It works on Lyme disease protocol, a malaria prevention plan, an acne prescription, and now a post-exposure STI regimen. Doxycycline really does treat five unrelated problems. It isn’t that the drug just has killer marketing (although, it totally does that). It’s pharmacology: one mechanism, several targets, and, as it turns out, a guideline landscape that doesn’t fully agree on how to use it.

Take the tick bite question. The Infectious Diseases Society of America, the American Academy of Neurology, and the American College of Rheumatology all endorse a single 200 mg dose within 72 hours of a high-risk bite¹. The International Lyme and Associated Diseases Society doesn’t². Same drug and window, yet different answer depending on which guideline you’re using.

What is doxycycline used for?

More than you’d expect from one antibiotic. Doxycycline treats Lyme disease, prevents malaria, clears chlamydia, controls acne and rosacea, and, as of a 2024 CDC update³, prevents certain bacterial STIs after exposure in specific patients. 

That’s not doxycycline being a jack-of-all-trades in the vague sense. It comes down to mechanism. Doxycycline blocks protein synthesis in bacteria, the same core action tetracyclines have always had. It also disrupts a structure inside the malaria parasite called the apicoplast, a leftover organelle the parasite can’t survive without.

Quick reference: doxycycline by indication

Treatment: Lyme disease (a 10-day course performs as well as longer regimens⁴), rickettsial infections, chlamydia, and acne or rosacea.

Prevention: a single 200 mg dose within 72 hours of a high-risk tick bite, or daily dosing started before travel to a malaria-endemic area⁵.

Adjunct: reduces gum-pocket depth after periodontal treatment⁶.

Anthrax exposure: 100 mg twice daily for 60 days⁷., the CDC’s long-standing post-exposure regimen following high-risk Bacillus anthracis exposure. This one’s been on the Strategic National Stockpile for over two decades, not a new addition.

Emerging and debated: a single post-exposure dose to reduce the risk of certain bacterial STIs. That one’s newest, and it’s not settled, so it gets its own section next.

Five categories, one drug. Four of which are on well-worn clinical ground.

Where this fits into appropriate medical preparation

Three of these five uses are built for a standby kit: the single tick-bite dose, prescribed before symptoms show up; the pre-travel malaria regimen, started before a patient ever sets foot somewhere with risk; and doxycycline kept on hand ahead of a possible anthrax exposure. These work only because they’re prescribed ahead of need, not after.

That’s what we mean by appropriate medical preparation: a bounded, clinician-controlled step for conditions where the evidence is strong and the timing is predictable well in advance.

Acne, chlamydia treatment, and Doxy-PEP don’t fit that same frame. Each is answering a different clinical question, on a different timeline. None of this is a replacement for primary care. It’s the same clinical standard we’d apply at the time of symptoms, just applied earlier, for the narrow slice of doxycycline’s uses where earlier actually helps.

The bottom line

Doxycycline’s breadth isn’t hype or overuse. It has a great mechanism that allows one antibiotic to serve in several clinical roles since it blocks protein synthesis in bacteria and disrupts a different structure entirely in the malaria parasite. Most of that list is settled, well-worn clinical ground. Doxy-PEP isn’t. CDC’s 2024 guidance applies it to a defined population, adults with a bacterial STI diagnosis in the past 12 months, not sexually active adults broadly³. That population has already been redrawn once: WHO issued its own endorsement in 2026, broadly aligning with CDC, while Europe’s ECDC held back, citing resistance concerns over a population-level rollout⁸ ⁹. 

The uses that actually belong in a standby kit, prescribed ahead of need, are the tick-bite dose, pre-travel malaria regimen, and anthrax exposure backup. That’s the appropriate medical preparation slice of this list, and it’s the piece Jase is built around.

Sources

1. IDSA/AAN/ACR 2020 Lyme guideline, single 200 mg dose within 72 hours of a high-risk tick bite. Infectious Diseases Society of America. idsociety.org/practice-guideline/lyme-disease
2. ILADS treatment guidelines (the dissenting position). ilads.org/patient-care/ilads-treatment-guidelines
3. CDC Clinical Guidelines on Doxycycline Postexposure Prophylaxis, MMWR 2024. Confirms 200 mg within 72 hours, population is MSM and transgender women with a bacterial STI in the past 12 months. cdc.gov/mmwr/volumes/73/rr/rr7302a1.htm
4. Shorter versus longer antimicrobial therapy for early Lyme disease, systematic review and meta-analysis, confirming no significant difference between ≤10-day and longer courses. sciencedirect.com/science/article/abs/pii/S0732889324000440
5. CDC Yellow Book, Malaria chapter, chemoprophylaxis dosing and timing. cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/malaria.html
6. Subantimicrobial-dose doxycycline (Periostat), FDA-approved 1998 as adjunct to scaling and root planing, reduces pocket depth. ncbi.nlm.nih.gov/pmc/articles/PMC6473443
7. CDC Anthrax Doxycycline Emergency Use Instructions, 100 mg twice daily for 60 days post-exposure. stacks.cdc.gov/view/cdc/56837/cdc_56837_DS1.pdf
8. WHO news release, first recommendation on doxycycline PEP, May 28, 2026. who.int/news/item/28-05-2026-who-issues-first-recommendation-on-doxycycline-post-exposure-prophylaxis
9. ECDC guidance on doxycycline for STI prevention, January 2026, recommends against population-level rollout. ecdc.europa.eu/en/news-events/ecdc-issues-guidance-doxycycline-sti-prevention