Additive QT-prolonging effects likely, see drugs that prolong the QT interval.
Concurrent use should generally be avoided.
Beta blockers, general
The concurrent use of chlorpromazine
and propranolol can result in a marked rise in the plasma
levels of both drugs. Propranolol also markedly increases plasma
thioridazine levels. Additive hypotensive effects are also possible, see antihyperten- sives.
Monitor the outcome of concurrent use, adjusting the doses of both drugs as necessary.