Antibiotic options: how to pick the right antibiotic

Antibiotics are powerful, but the right choice depends on the bug and the body. If you have an infection, knowing the common options helps you ask better questions at the clinic or pharmacy. Below I’ll walk you through the main classes, typical uses, safety flags, and quick tips for buying meds safely online.

Common antibiotic classes and when they're used

Penicillins (like amoxicillin) - Often first choice for ear infections, strep throat, and some sinus infections. They’re usually well tolerated unless you have a true penicillin allergy.

Cephalosporins (cephalexin) - Good for skin infections and some urinary or respiratory infections. They’re a common backup when penicillins aren’t ideal.

Macrolides (azithromycin) - Used for some respiratory infections and when someone is allergic to penicillin. Azithromycin is popular because of short courses, but it can interact with other meds.

Tetracyclines (doxycycline) - Often used for acne, certain tick-borne illnesses, and some respiratory infections. Not for kids under 8 or pregnant people.

Fluoroquinolones (ciprofloxacin, levofloxacin) - Strong broad-spectrum drugs used for complicated UTIs and certain resistant infections. They carry higher risk of tendon and nerve problems, so doctors avoid them unless necessary.

Sulfonamides (trimethoprim-sulfamethoxazole) - A common choice for uncomplicated UTIs and some skin infections like MRSA. Watch for allergic reactions and sun sensitivity.

Nitrofurantoin and fosfomycin - Targeted options for uncomplicated bladder infections (UTIs). They act mainly in the urinary tract and are often first-line for simple cystitis.

Metronidazole - Used for anaerobic infections and some gut issues like certain diarrheas and pelvic infections. Alcohol should be avoided while taking it and for a short time after.

How to choose and stay safe

Get a diagnosis first. Swabs or urine tests guide the right drug and prevent unnecessary use. If a culture isn't possible, doctors pick based on the likely bug and local resistance patterns.

Tell your provider about allergies, pregnancy, kidney or liver problems, and other drugs you take. These details change the safest choices.

Finish the course as directed and don’t save or share antibiotics. Stopping early or underdosing helps resistance grow. If symptoms don’t improve in 48–72 hours, contact your provider.

Buying online? Use pharmacies that require a prescription, show licensing, have clear contact info, and accept secure payments. If a site sells prescription antibiotics without a prescription, walk away.

Worried about resistance or side effects? Ask your provider for alternatives or a specialist referral. Knowing the common classes and safety flags makes conversations with healthcare teams faster and smarter.

If you want short summaries of specific antibiotics or help spotting safe online pharmacies, CanadianPharmacyService.com has plain-language guides and reviews you can check.