Objective: This study aimed to assess whether coffee consumption affects the efficacy or onset time of local anesthesia (LA) in healthy adults using electric pulp testing (EPT). Method: A single-blinded, randomized, exploratory pilot crossover clinical trial was conducted at the dental hospital at Umm Al-Qura University. Ten healthy participants (five females, five males; aged 18–30 years) with intact upper premolars were included. Each participant served as both the intervention (coffee) and control (no coffee) group within one month. In the intervention session, participants consumed one cup of instant coffee containing approximately 45–50 mg of caffeine, a low-to-moderate caffeine dose, and waited 20 min before testing. EPT was used to assess pulpal anesthesia following administration of 2% lidocaine with 1:100,000 epinephrine. EPT measurements were recorded pre- and post-LA. Effectiveness was compared using McNemar’s test, and onset time was analyzed using paired t-tests. Results: All participants achieved complete pulpal anesthesia (maximum EPT reading = 64) in both coffee and no-coffee sessions. This uniform response produced a measurement ceiling effect, precluding meaningful statistical comparison. The mean pre-LA EPT readings were 20.4 ± 6.9 (range 9–31.3) for the control group and 24.3 ± 7.2 (range 14–37.3) for the coffee group. Both groups achieved anesthesia within approximately two minutes. Conclusion: From this preliminary study, coffee consumption did not affect the onset or effectiveness of local anesthesia in healthy adults. Within the limitations of this small crossover pilot study, these findings indicate no observable difference, though not definitive equivalence. Larger-scale studies are warranted to confirm these preliminary results.