∞ generated and posted on 2016.03.21 ∞

Property of two or more drugs that, when used together, their combined effectiveness is greater than would have been anticipated based upon their effectiveness when used alone.

Two bactericidal antibiotics are more likely to have synergistic interactions than a bactericidal antibiotic with a bacteriostatic antibiotic. See by contrast antagonism.

Note that synergy more broadly may be defined as "greater than the sum of the parts" and this is true with antibiotics as well. Thus, in combining antibiotics there should be an increase in overall efficacy ("the sum of the parts") but with synergy there should be an even greater combined impact. In other words, synergy can be viewed as equivalent to 'hitting' bacteria 'while they are down', with one of the antibiotics at least providing the initial 'punch' and the other the subsequent 'kick'. (With "initial", "punch", "kick", and "subsequent" all being used more metaphorically than as actually actions or orders.)