subtherapeutic

adjective

sub·​ther·​a·​peu·​tic ˌsəb-ˌther-ə-ˈpyü-tik 

variants or sub-therapeutic

: less than therapeutic : having, using, or being a dose that is below what is used for treating disease or producing an optimal therapeutic effect

… with a fixed dose of 95 mg/kg/day, initial levels during the febrile phase were subtherapeutic (<20 mg/dL)…

—Gideon Koren et al.

Farm animals are the target of nearly half the antibiotics produced in the United States, mostly in the form of low or subtherapeutic doses aimed at preventing disease or promoting growth.

—Karen Wright

Word History

First Known Use

1910, in the meaning defined above

Medical Definition

subtherapeutic

adjective

sub·​ther·​a·​peu·​tic -ˌther-ə-ˈpyüt-ik 

: not producing a therapeutic effect

subtherapeutic doses of penicillin