Yes, sometimes the culture tests show the right antibiotic. It shows percentages of which Antibiotics will be more likely to work. Now, they do not test all Antibiotics . And the one with the highest percentage might be 50% so that means a 50/50 chance. Last year, an Antibiotic with the highest percentage in a culture test did not work for a urinary tract infection my mom had. Actually, the Antibiotic that worked for her was the one with a lower percentage. I cannot explain why this sometimes happens. But I also think you may need to apply it directly to lips instead of ingesting it.