Strep Throat Recovery: How Long After Biocillin Treatment?

Biocillin (penicillin G benzathine) is a long-acting injectable penicillin. For strep throat (Streptococcus pyogenes/Group A Strep):

• Symptom improvement: Often within 24–48 hours
• Contagious period ends: 24 hours after injection
• Full course: Single injection typically sufficient (vs. 10-day oral penicillin)
• Complete resolution: 3–5 days typical

Critical Points

• Penicillin remains first-line—no resistance documented
• Return to school/work after 24 hrs on antibiotics + afebrile
• Finish any prescribed oral antibiotics if given instead
• Follow up if no improvement in 48 hrs or worsening

Complications (peritonsillar abscess, rheumatic fever, post-strep glomerulonephritis) are rare with prompt treatment.