Medicine & USMLE


In Progress
  1. Terbutaline
  2. Radioactive Iodine
  3. Ipratropium / Tiotropium
  4. Levothyroxine
  5. Second Generation Antihistamines
  6. First Generation Antihistamines (Diphenhydramine)
  7. Inhaled Steroids
  8. Antitussives
  9. Hypokalemia


Antitussives are drugs that work to treat coughing, and include the opioid drugs dextromethorphan and codeine. Suppression of coughing can lead to an accumulation of airway secretions, the most notable side effect of taking these drugs. Other side effects common to opioids can also occur, including constipation, respiratory depression, nausea and vomiting, and orthostatic hypotension. Lastly, as opioid drugs, these drugs have abuse potential since they may cause tolerance and dependence.

Key Points

  • Antitussives
    • Key Drugs
      • Dextromethorphan (Benylin)
      • Codeine
    • Mechanism
      • Codeine suppresses the cough reflex by depressing the CNS
      • Codeine is an opioid, and dextromethorphan is a partial-opioid, meaning it works on some (but not all) of the opioid receptors.
    • Clinical Uses
      • Cough suppression
        • Codeine is used for chronic nonproductive cough
        • Dextromethorphan is found in many different cough products
        • Most effective at treating a dry, nonproductive cough.
          • Productive coughs are better treated with a mucolytic to mobilize secretions
    • Side Effects and Adverse Reactions
      • Accumulation of airway secretions
        • Suppressing the cough reflex may prevent pulmonary secretions to build up in the lungs
        • Do not give to patients with COPD or other respiratory disorders
      • Respiratory depression
        • Due to CNS depression in medulla
        • Stimulate the patient to breathe if respiratory rate drops below 12 breaths/minute.
        • Antidote is naloxone
      • Constipation
        • Due to opioid suppression of gut motility
      • Nausea/vomiting
      • Orthostatic hypotension
        • May also be accompanied by dizziness or drowsiness
        • Advise patients to change positions slowly to avoid sudden drop in blood pressure
      • Abuse potential
        • Only use for a short duration
        • Abuse potential is higher for codeine, but dextromethorphan can instill euphoria in high doses and therefore does have some potential for abuse