You started the antibiotic three days ago, and the tooth still throbs. Plenty of people around North Austin end up here, especially when the prescription came from an urgent care or a video visit instead of a dentist. It usually is not the wrong medication.

Antibiotics rarely fail because the drug is wrong. They fail because they cannot reach the source, which sits inside a tooth that no longer has a working blood supply. If you are not clearly improving within 48 to 72 hours, that is the point to call a dentist rather than wait out the course.
When decay or a crack reaches the nerve, the tissue inside the tooth dies. Everything past that point is sealed off from your circulation, so an antibiotic in your bloodstream reaches the swelling around the tooth but never the bacteria living inside it. Dr. Tarsem Lal describes the medication as buying time, not solving anything: it can shrink the swelling enough to make treatment comfortable, which is often exactly why it was prescribed.
That is also why swelling that has walled itself into a pocket needs to be opened and drained. An abscess under pressure will not respond to tablets alone.
If the antibiotic has done nothing at all, the pain may not be an infection. An inflamed but still living nerve, a cracked tooth, sinus pressure on the upper back teeth, and a healing extraction site can all hurt badly, and none of them improve on antibiotics. Each needs a different fix, which is why an exam and an X-ray settle this faster than a second prescription.
Urgent care clinics and freestanding emergency centers along I-35 are easy to get into same-day, and they will write the prescription and tell you to see a dentist. That's reasonable as a first step, but the clock starts there, and the appointment is the part people postpone. Miss the window and you are into the weekend, when most general dental offices in this city are shut. Weekend emergency dental care exists here, so a Friday flare-up does not have to wait until Monday.
If swelling starts spreading into your cheek, jaw, or neck, if you develop a fever, or if opening your mouth or swallowing becomes difficult, skip all of this and go to a hospital emergency room. If it is still local, you can walk in instead.
How long should antibiotics take to work on a tooth infection?
Most people notice the swelling and pain easing within 24 to 48 hours. If nothing has changed by 72 hours, or things are getting worse, call rather than finish the course and hope.
Should I ask for a stronger antibiotic?
Usually that is not the answer. A different drug helps only in the small number of cases where the first one did not cover the bacteria involved, and it still cannot reach inside the tooth. The exam is what tells you which situation you are in.
The pain is gone. Do I still need the tooth treated?
Yes. Pain often stops because the nerve finished dying or the pressure found somewhere to drain, not because the infection cleared. Treating it usually means a root canal or taking the tooth out, and it comes back without one of them.