Antibiotic Therapy: When to Start, When to Switch

Antibiotics save lives, but they don’t always work the first time. Resistance is rising and that changes how doctors choose and change treatments. This page pulls together practical, plain-language guidance so you know what to expect and when to call your clinician.

When to change antibiotics

If you start treatment and feel worse after 48–72 hours, that's a red flag. Persistent or higher fever, spreading redness or swelling, new shortness of breath, or rising pain usually means the current drug isn't doing the job. For common respiratory infections, clinicians often start with amoxicillin; they may switch to Augmentin or a cephalosporin if symptoms fail to improve, especially when there are risk factors like recent antibiotic use, severe illness, or signs of resistant bacteria.

For dental infections, amoxicillin is common but not always an option. If you’re allergic to penicillin or the infection doesn’t respond, dentists may choose clindamycin or a metronidazole combo. Typical practice-level notes: clindamycin covers many oral bacteria and can be given when penicillin allergy is present; metronidazole is useful for anaerobic bugs and is often combined with another drug. Exact doses depend on the infection and your health — follow your prescriber's instructions.

There are specific cases where a test matters. When doctors suspect resistant organisms (for example, certain sexually transmitted infections or complicated skin infections), they’ll request cultures and sensitivity testing. That allows them to de-escalate to a narrow, effective antibiotic instead of guessing.

Smart antibiotic use for patients

Use these rules to avoid problems: 1) Take the drug exactly as prescribed — same dose, same timing. Missing doses or stopping early can encourage resistance. 2) Tell your provider about allergies, other meds, pregnancy or liver/kidney problems — these affect choice and dose. 3) Don’t share antibiotics or use leftover pills. 4) Avoid buying antibiotics from unverified online sellers; counterfeit or wrong meds are common and dangerous.

Antibiotic resistance matters right now. Some strains of syphilis and gonorrhea have shown reduced response to older antibiotics like azithromycin, pushing doctors to use specific recommended regimens only. That’s why health authorities update treatment guides — and why your doctor may choose a different pill than your friend got last year.

Watch for side effects: diarrhea, rash, or new fever. Severe reactions (trouble breathing, swelling, high fever, severe diarrhea) need urgent care. If a prescribed antibiotic causes bad side effects, stop and contact your provider — they’ll advise the safest next step.

Bottom line: effective antibiotic therapy is about timing, the right drug for the bug, and responsible use. Ask your clinician about culture tests when infections don’t improve, and always follow dosing advice. That helps you get better faster and keeps antibiotics working for everyone.

The Use of Tobramycin in the Treatment of Prosthetic Joint Infections
Angus MacAlister 2 August 2023
The Use of Tobramycin in the Treatment of Prosthetic Joint Infections

Oh boy, today we're diving deep into the world of medical marvels! Let's chat about Tobramycin, a super-hero in the treatment of prosthetic joint infections. If your artificial joints are acting up, Tobramycin is the guy you call! It's like the plumber of the body, fixing leaky pipes and creaky knees. So, let's give a big round of applause to Tobramycin, making our bionic bodies tick just right!