Introduction
Antibiotics are powerful medicines, but they are not universal cures. Many illnesses that look and feel severe, like cough, fever, sore throat, earache, may in fact be viral and do not require antibiotics at all. Prescribing them in such cases brings no benefit and carries risks: side effects, resistance, and disruption of the microbiome.
This guide focuses on the conditions where antibiotics are truly indicated. It explains when bacterial infection is likely, which drugs are typically chosen, and why dosing varies for adults and children. Each section links to practical resources: dosing rules (see Dosing adults, Dosing children), dosage forms (Forms), and how to take medicines correctly (How to take). For those who want to learn more about individual drugs, detailed references are available (16–22).
Tonsillitis and pharyngitis
Sore throat is one of the most frequent reasons people visit a doctor, and one of the most common areas of antibiotic misuse. Most sore throats are viral, caused by rhinoviruses, adenoviruses, or influenza. Antibiotics bring no relief in these cases.
The key exception is streptococcal pharyngitis, also known as strep throat, caused by Streptococcus pyogenes (Group A strep). It typically presents with sudden throat pain, fever, swollen tonsils with white patches, and absence of cough. Laboratory confirmation (rapid antigen test or throat culture) helps distinguish it from viral infections.
When strep throat is confirmed, antibiotics are essential. They not only shorten symptom duration by about a day but, more importantly, prevent complications such as rheumatic fever and post-streptococcal glomerulonephritis.
- First-line choice: Amoxicillin. It is effective, well tolerated, and suitable for children and adults.
- Alternative for penicillin allergy: Azithromycin or other macrolides.
- Pediatric dosing: based on weight; suspensions are common. See Dosing children.
- Adult dosing: standard regimens are described in Dosing adults.
Correct duration matters. A full course is needed to fully eradicate bacteria, even if symptoms improve sooner. Patients who stop early risk relapse and resistance.
Sinusitis
Sinus infections are a frequent cause of doctor visits, but most cases are viral and resolve within a week without antibiotics. Antibiotic therapy is reserved for bacterial sinusitis, which is less common.
Doctors usually look for a combination of warning signs to tell the difference. These include symptoms persisting longer than 10 days without improvement, severe facial pain or swelling around the eyes, high fever with purulent nasal discharge, or a “double-sickening” pattern where initial improvement is followed by worsening.
When bacterial sinusitis is likely, treatment is appropriate. The first-line choice is amoxicillin or Amoxicillin-clavulanate, because it covers common resistant pathogens. Alternatives include Doxycycline in adults and cephalosporins such as Cephalexin.
Course length is typically 5–7 days for adults and 10 days for children, with pediatric dosing calculated by weight Dosing children. Adults follow standardized regimens Dosing adults. To avoid relapse and resistance, patients must complete the full course, as emphasized in How to take.
Sinusitis highlights a broader lesson: antibiotics bring real benefits when the infection is bacterial, but for viral cases they only add risks.
Otitis media
Ear infections, particularly acute otitis media, are among the most common reasons children receive antibiotics. Yet here too, clinical judgment is crucial. Not every case requires pharmacological intervention. Many mild infections in toddlers resolve spontaneously within 48–72 hours, provided pain is managed. The challenge lies in distinguishing viral inflammation of the middle ear from a true bacterial infection.
High fever, bulging of the eardrum, marked irritability in a child, or persistent ear pain are features that push the balance toward bacterial disease. When these signs are present, antibiotic therapy is justified.
Amoxicillin remains the gold standard for first-line therapy due to its efficacy, safety profile, and tolerability in children. In cases of recurrent or resistant infections, or when Haemophilus influenzae and Moraxella catarrhalis are suspected, the combination Amoxicillin-clavulanate may be chosen instead. For patients allergic to penicillins, macrolides such as Azithromycin provide a reasonable alternative.
Precise dosing is particularly critical in pediatrics. Calculations are based on weight, and formulations often come as flavored suspensions to improve adherence. Regardless of age, completion of the prescribed course is non-negotiable, since premature discontinuation fosters relapse and antimicrobial resistance.
Otitis media thus exemplifies a broader theme: antibiotics are invaluable when bacterial infection is clear, but restraint is equally important when observation and symptomatic care suffice.
Bronchitis
Few conditions demonstrate the overuse of antibiotics more clearly than acute bronchitis. Characterized by a lingering cough, often following an upper respiratory infection, it is overwhelmingly viral in origin. The inflammation of the bronchial tubes may persist for weeks, yet no antibiotic can shorten its course. Prescribing them in these cases provides only placebo reassurance while exposing patients to unnecessary risk.
There are, however, exceptions that justify antibiotic use. The most important are bacterial bronchitis in vulnerable patients and exacerbations of chronic obstructive pulmonary disease (COPD), where bacterial superinfection can tip the balance toward respiratory failure. In such settings, antibiotics may improve outcomes by reducing bacterial load and preventing further deterioration.
Therapeutic options depend on the suspected pathogen. Doxycycline is often chosen for its broad coverage, especially in COPD exacerbations, while macrolides such as Azithromycin provide an alternative in penicillin-allergic patients or when atypical bacteria are suspected.
Still, it bears repeating: routine use of antibiotics in acute bronchitis is not recommended. Doing so not only fails to help the patient but also accelerates antimicrobial resistance. Symptomatic relief, hydration, and rest remain the pillars of management in the vast majority of cases.
Pneumonia
Unlike bronchitis, where antibiotics are usually unnecessary, pneumonia is the quintessential bacterial respiratory infection, and antimicrobial therapy is indispensable. Pneumonia represents infection of the lung parenchyma itself, producing fever, cough with purulent sputum, chest pain, and infiltrates on chest imaging. Delayed or inadequate treatment can rapidly progress to sepsis or respiratory failure.
The microbial spectrum of pneumonia is broad, with Streptococcus pneumoniae remaining the most common culprit in community-acquired cases. Other agents include Haemophilus influenzae, atypical organisms such as Mycoplasma pneumoniae, and, in hospital settings, more resistant Gram-negative bacilli. Because of this diversity, empiric therapy is guided by local resistance data, patient age, comorbidities, and illness severity.
For community-acquired pneumonia in otherwise healthy adults, amoxicillin is the standard first-line choice, with Doxycycline or Azithromycin often used as alternatives, especially where atypical pathogens are suspected. In children, Amoxicillinremains the drug of choice.
For more severe infections, or in patients with comorbidities, the broader-spectrum Amoxicillin-clavulanate is preferred, sometimes in combination with a macrolide to cover atypicals. Cephalosporins such as Cephalexin may be used for milder cases, though higher-generation cephalosporins or intravenous regimens are required for hospitalized patients.
In all situations, duration and dosing must be tailored carefully. Too short a course risks relapse, while overly prolonged therapy contributes to resistance and adverse effects.
Pneumonia illustrates the best of antibiotics: when prescribed correctly, they transform a potentially fatal disease into a manageable condition. But it also underscores the need for precision: the right drug, at the right dose, for the right duration.
Urinary tract infections
UTIs are among the clearest examples of conditions that genuinely require antibiotics. Unlike many viral respiratory illnesses, infections of the urinary tract are almost always bacterial in origin. Left untreated, even a seemingly mild bladder infection can progress to the kidneys, causing fever, flank pain, and, in severe cases, sepsis.
The main therapeutic goal is therefore not only to relieve discomfort like burning, frequent urination, lower abdominal pain, but to prevent complications. Antibiotics shorten the course of illness, sterilize the urine, and protect against upward spread of infection.
Special attention is needed in children and in older adults, since UTIs may indicate hidden anatomical or functional problems. Prompt and accurate treatment is essential, but so is restraint: asymptomatic bacteriuria (bacteria in the urine without symptoms) does not usually require antibiotics, and overtreating it contributes to resistance.
Skin and soft tissue infections
Skin is our first barrier against microbes, and when it is breached by cuts, insect bites, or surgical wounds, bacteria can take hold. Most mild infections, like small boils, may resolve with drainage and local care, but when inflammation spreads into deeper layers, antibiotics become essential.
Cellulitis, for instance, is characterized by redness, warmth, swelling, and pain. Without antibiotics, it can progress rapidly, leading to abscess formation or bloodstream infection. Here, treatment aims not only to control local symptoms but to prevent systemic complications. Typical first-line agents are cephalosporins such as Cephalexin, chosen for their reliable activity against Streptococcus and Staphylococcus. In areas where resistant staphylococci (MRSA) are common, alternatives like Doxycycline may be used. Dental abscesses, another form of soft tissue infection, often require Metronidazole to control anaerobic bacteria.
The broader point, however, is that antibiotics protect patients when infections threaten to spread beyond local control. Careful selection of drug and dose, guided by infection type and patient factors, ensures that these everyday yet potentially serious conditions remain manageable.
Dentistry
Dental problems are among the most common reasons patients receive antibiotics, and also one of the areas of greatest overuse. Most toothaches are not bacterial infections but result from inflammation of the pulp or gums. In such cases, antibiotics add no benefit; the real solution is dental treatment.
Antibiotics become necessary when infection spreads beyond the tooth itself: abscesses that cause facial swelling, cellulitis of the jaw, or peri-implant infections. In these situations, therapy is not only about symptom relief but about preventing dangerous complications such as deep neck infections or even sepsis.
Dentists typically rely on Amoxicillin as a first-line agent, sometimes combined with Metronidazole when anaerobic bacteria are suspected. But drugs are never substitutes for mechanical intervention: drainage, root canal, or extraction remain the cornerstone of care.
Antibiotics in dentistry are supportive, not curative. They are indicated only when bacterial spread is evident, and they must always be paired with proper dental treatment.
General notes and conclusion
Antibiotics are powerful, but they are not universal remedies. Their role is precise, i.e., to treat infections that are truly bacterial in origin, where the risk of complications outweighs the risks of the drugs themselves.
For sore throats, antibiotics matter only when streptococcal infection is proven. For sinusitis and ear infections, careful distinction between viral and bacterial disease is essential. In bronchitis, antibiotics are rarely needed, while in pneumonia they are indispensable. UTIs and skin infections illustrate the duality: antibiotics can be life-saving, yet careless prescribing for harmless or self-limiting situations fuels resistance. Dentistry further underlines the point that mechanical treatment often outweighs drug therapy.
To use antibiotics safely, patients and clinicians alike must also consider dosing Dosing adults, Dosing children, dosage forms (Forms), and intake rules (How to take). Individual drug characteristics are equally important.
Used wisely, antibiotics turn life-threatening conditions into manageable illnesses. Used carelessly, they contribute to resistance, side effects, and wasted treatment.