Why most sore throats don’t need antibiotics
Viruses cause around 80–90% of adult sore throats and about 70% in children. Antibiotics kill bacteria, not viruses, so they will not speed recovery from a cold or flu. Taking them unnecessarily exposes you to side effects, can disrupt gut bacteria, and contributes to antibiotic resistance. Most viral sore throats improve within a week with self-care. See sore throat remedies and pharyngitis.
When antibiotics are useful: strep throat
Group A streptococcus causes about 10% of adult and 20–30% of child sore throats. Typical features are sudden severe sore throat, painful swallowing, fever, swollen red tonsils with white patches, tender neck glands and the absence of cough or runny nose. Doctors often use a scoring system (Centor or McIsaac) and confirm with a rapid antigen test or throat culture. Treating strep reduces symptoms by about a day, shortens contagiousness and prevents rare complications such as rheumatic fever and peritonsillar abscess. See strep throat.
Other situations where antibiotics may be needed
- Peritonsillar abscess (quinsy): antibiotics plus drainage.
- Scarlet fever and other confirmed group A strep infections.
- Diphtheria, gonococcal pharyngitis and other rare bacterial causes, identified by tests.
- Recurrent tonsillitis with proven bacterial infection.
- Complicated sinus or ear infections that accompany the sore throat. See sinus infection symptoms.
- People at high risk, such as those with weakened immunity or a history of rheumatic fever, as advised by a doctor.
Which antibiotics are used
- Penicillin V (oral, usually 10 days) or amoxicillin (10 days, or shorter courses of 5–7 days in some guidelines): first choice.
- Cephalexin or cefadroxil for mild penicillin allergy.
- Clindamycin for severe penicillin allergy.
- Azithromycin or clarithromycin are alternatives, but resistance is rising.
- Intramuscular benzathine penicillin G as a single injection if tablets cannot be taken reliably.
- Always finish the course unless your doctor advises otherwise, and do not share or save antibiotics.
How doctors decide
- Fever, tonsillar swelling or exudate, tender neck nodes and absence of cough raise the chance of strep.
- A rapid antigen test provides a result in minutes; a negative test in children is often followed by a culture.
- In adults, a negative rapid test often rules out strep because complications are rare.
- A “delayed prescription” may be given when infection is possible but not certain, to be used only if symptoms worsen after 2–3 days.
- Blood tests are used if glandular fever (mononucleosis) is suspected, because amoxicillin can cause a rash in this condition.
Side effects and risks
- Diarrhoea, nausea and stomach upset are common.
- Rash or hives; seek help for swelling or breathing difficulty (allergy).
- Oral or vaginal thrush after a course.
- Interactions with other medicines, such as the contraceptive pill (rarely) and warfarin.
- Clostridioides difficile infection (severe diarrhoea) after antibiotics.
- Antibiotic resistance, which makes future infections harder to treat.
- Many people feel better in 24–48 hours, but finishing the course is still advised for strep.
What helps while waiting for antibiotics to work
- Paracetamol or ibuprofen for pain and fever.
- Plenty of fluids, soft foods, and warm drinks with honey (not for babies under 1).
- Salt-water gargles and lozenges.
- Rest and a humid room.
- Avoid smoking, alcohol and spicy foods.
- Stay home until fever settles and you have had at least 12–24 hours of antibiotics for strep.
Preventing spread
- Wash hands often and avoid sharing cups, cutlery or toothbrushes.
- Cover coughs and sneezes with a tissue or elbow.
- Replace your toothbrush after 24 hours on antibiotics for strep.
- Stay off work or school until you are well and, for strep, 12–24 hours into treatment.
- Vaccination against flu and COVID-19 as advised.
- Avoid smoking and smoke exposure.
When to see a doctor
- Sore throat with high fever, white patches and swollen glands.
- Trouble swallowing, drooling, trouble opening the mouth or a muffled voice: urgent.
- Sore throat lasting more than a week, or recurring repeatedly.
- Rash, joint pain or dark urine after a sore throat.
- Symptoms not improving after 48–72 hours on antibiotics.
- Weak immunity, diabetes or heart valve disease.
- Children with high fever, refusal to drink or lethargy.
Three common situations
An adult with a sore throat, runny nose and cough for two days: viral; antibiotics will not help.
A teenager with sudden severe sore throat, fever and white patches and no cough: test for strep; antibiotics if positive.
A person with severe one-sided pain, trouble opening the mouth and a muffled voice: possible abscess; seek urgent care.
Key points to remember
Most sore throats do not need antibiotics. They are for confirmed strep throat and bacterial complications. Use pain relief and fluids for viral cases, take antibiotics exactly as prescribed when needed, and seek care for red flags. Our ENT team can test and treat throat infections.
This guide is for general information and does not replace an examination by your own doctor or ENT specialist.
Questions about antibiotics for sore throat
These answers are general information and do not replace an examination or individual medical advice.
Do I need antibiotics for a sore throat?
Usually not; most are viral and clear by themselves. They are for confirmed or highly likely strep throat.
Which antibiotic treats strep throat?
Penicillin V or amoxicillin, usually for 10 days, with alternatives for allergy.
How fast do antibiotics work?
Symptoms improve in 24–48 hours, though the main goals are shortening illness, reducing spread and preventing complications.
Can I take leftover antibiotics?
No; they may be the wrong type or dose and fuel resistance.
When am I no longer contagious with strep?
About 12–24 hours after starting effective antibiotics and when fever has gone.
What if my sore throat doesn’t improve on antibiotics?
See your doctor; it may be viral, resistant, an abscess or another diagnosis.
Sources
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.