What is a common adverse reaction to codeine when used as an antitussive?

Drowsiness is a common adverse reaction associated with codeine when used as an antitussive. Codeine is an opioid that acts on the central nervous system to suppress the cough reflex. One of the primary effects of many opioids, including codeine, is sedation due to their influence on brain function and neurotransmitter activity. This sedative effect can lead patients to experience drowsiness or fatigue, making this a noteworthy side effect when prescribing codeine for cough relief.

The central nervous system depressant effects of codeine can also interfere with a patient's ability to perform tasks that require alertness, such as driving or operating machinery. This consideration is essential for healthcare providers when advising patients on potential side effects and the safety of their activities while taking codeine.

Other possible adverse reactions to consider include gastrointestinal disturbances and respiratory depression, but drowsiness is particularly salient due to its impact on daily functioning.