I was in close proximity to someone with strep throat 20 hours after they started antibiotics, and now I have a deep sore throat, could I have contracted strep throat?

Risk of Strep Transmission After 20 Hours of Antibiotics

You are extremely unlikely to have contracted strep throat from your friend, as patients on appropriate antibiotics for 20 hours are no longer considered contagious. 1

Why You're Probably Safe from Transmission

• Patients with strep pharyngitis become non-contagious within 24 hours of starting appropriate antibiotic therapy, and your exposure at 20 hours falls just within this window when transmission risk is already dramatically reduced. 1

• The likelihood of transmission from someone on antibiotics is extremely small, as pharyngeal carriers (even untreated ones) show minimal risk of spreading infection to close contacts. 1

• Your "deep sore throat" is most likely viral pharyngitis or another non-streptococcal cause, since the vast majority (over 65%) of sore throats in adults are viral and don't require antibiotics. 1

What Your Symptoms Actually Suggest

• Viral pharyngitis is far more common than strep throat in adults, accounting for the majority of sore throat cases, and typically presents with symptoms like yours. 1, 2

• True strep pharyngitis usually presents with specific features: persistent fever, tonsillar exudates, tender anterior cervical lymph nodes, and notably the absence of cough. 1, 3

• A "deep" sore throat alone, without these other features, makes strep throat unlikely and suggests you don't need testing or treatment at this point. 3

When You Should Actually Get Tested

Use the Centor criteria to decide if you need testing:

• 0-1 criteria present: No testing needed, treat symptoms only. 3
• 2 criteria present: Consider testing with rapid strep test. 3
• 3-4 criteria present: Get tested before taking antibiotics. 3

The four Centor criteria are:

• Fever (temperature elevation)
• Tonsillar or pharyngeal exudates (white patches on throat)
• Tender anterior cervical lymph nodes (swollen, painful neck glands)
• Absence of cough (this is critical—cough suggests viral infection) 3

What You Should Do Right Now

• Take over-the-counter pain relievers like ibuprofen, acetaminophen, or naproxen for symptom relief, which are the recommended first-line treatments for sore throat. 3, 4

• Use throat lozenges for additional comfort, as these provide effective symptomatic relief. 1

• Expect your symptoms to resolve within 7 days even without antibiotics, as this is the typical course for most sore throats. 1, 4

• Only seek testing if you develop 2 or more Centor criteria, particularly fever with exudates and tender neck lymph nodes without cough. 3

Critical Red Flags (Seek Immediate Care)

Go to urgent care or the ER immediately if you develop:

• Difficulty swallowing or drooling
• Neck swelling or severe neck tenderness
• Trouble breathing or stridor
• Severe unilateral throat pain with inability to open your mouth (trismus)

These symptoms suggest life-threatening complications like peritonsillar abscess, retropharyngeal abscess, or epiglottitis that require urgent evaluation. 1, 3, 5

Common Pitfalls to Avoid

• Don't seek antibiotics without confirmed testing, as antibiotics only shorten symptom duration by 1-2 days even when strep is confirmed, and most sore throats don't need them. 1, 3

• Don't assume you have strep just because you were exposed, since transmission after 20 hours of antibiotic treatment is extremely unlikely and viral causes are far more common. 1

• Don't get tested if you have cough, runny nose, or congestion, as these symptoms indicate viral infection and testing will only lead to false-positive results in asymptomatic carriers. 3