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Which Acne Medications Are Most Effective against Propionibacterium


The objective is to determine which acne medications are the most effective in
inhibiting the growth of
Propionibacterium acnes, over-the-counter or prescription.


The active ingredients of two prescription antibiotics, three over the counter
acne medications and two
plant extracts were tested in vitro in duplicate two separate times against P.
acnes. The bacterium was
incubated under anaerobic conditions in the presence of disks containing the
study medications and a
control disk. The diameter of each inhibition zone was measured to the nearest
millimeter and recorded.


Tetracycline was the most effective, with an average inhibition zone of 46.25
mm, followed by
Clindamycin with a 45.5 mm inhibition zone. Surprisingly, Oregano oil had the
third largest inhibition
zone of 31.25 mm. Benzoyl peroxide 10%, Benzoyl peroxide 2.5%, the equal mix of
Tea Tree oil and
Oregano oil followed with inhibition zones of 24.75 mm, 23 mm, and 19.67 mm
zones, respectfully.
Lastly, with inhibition zones of 0 mm were the control, Salicylic acid, and Tea
Tree oil.


The prescription acne medications are the most effective in vitro against
Propionibacterium acnes.