A severe tooth infection, often called a dental abscess, occurs when bacteria invade the soft tissue inside the tooth (the pulp) or the surrounding gum and bone. This leads to a painful pocket of pus at the root tip. Penicillin is a common first-line antibiotic because it is highly effective against the types of bacteria typically found in oral infections. While penicillin treats the active infection, it does not resolve the underlying dental problem, which requires professional treatment like a root canal or extraction.
The Timeline of Symptom Relief
Penicillin begins working immediately upon entering the bloodstream by attacking bacterial cell walls, causing the bacteria to die. However, the speed at which this action translates into noticeable symptom reduction is often delayed. During the first 24 hours of treatment, the medication builds up in the body and starts reducing the bacterial load, but patients typically experience little significant improvement.
Observable relief usually begins within 48 to 72 hours after starting the antibiotic regimen. By this point, the population of infection-causing bacteria has been significantly reduced, allowing the body’s inflammatory response to subside. Patients should expect a noticeable decrease in localized swelling, pain, and any associated fever.
Feeling better after three days is a positive sign that the medication is controlling the infection. However, this relief does not mean the infection has been fully eradicated from the deeper tissues. Killing all bacteria requires a longer duration of consistent medication.
Why Completing the Full Course is Essential
The standard course of penicillin for a dental infection typically lasts between 7 to 10 days, regardless of how quickly symptoms improve. Symptoms fade once the majority of bacteria are killed, but a small population of the toughest bacteria may still survive. Stopping the medication early allows these surviving, stronger bacteria to multiply without competition.
Premature cessation of the drug is a major contributor to antibiotic resistance. When only the most resilient bacteria remain, they can pass on resistance traits, rendering penicillin ineffective for future infections. Therefore, the full course must be completed exactly as prescribed to ensure the complete elimination of all bacteria.
Signs That Require Immediate Follow-Up
While penicillin is highly effective, specific signs indicate the infection is not responding or is rapidly worsening. If there is no noticeable improvement in pain, fever, or swelling after 72 hours, the antibiotic may not be effective against the specific bacterial strain. This situation warrants immediate contact with the prescribing dentist or physician to adjust the treatment plan.
More serious signs indicate the infection is spreading or becoming severe. These include swelling spreading rapidly to the eye, neck, or throat. Difficulty swallowing or breathing, coupled with a spiking fever, suggests the infection may be entering the bloodstream, necessitating emergency medical attention. Additionally, any sign of a severe allergic reaction to penicillin, such as hives or swelling of the face and lips, requires immediate emergency care.