Codeine / guaifenesin Side Effects
Not all side effects for codeine / guaifenesin may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.
For the Consumer
Applies to codeine / guaifenesin: capsules, liquid, tablets
Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur while taking codeine / guaifenesin:
Dizziness; drowsiness; excitability; headache; nausea; nervousness or anxiety; trouble sleeping; weakness.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); difficulty urinating; fast or irregular heartbeat; hallucinations; seizures; severe dizziness, lightheadedness, or headache; severe drowsiness; tremor.
For Healthcare Professionals
Applies to codeine / guaifenesin: oral capsule, oral liquid, oral syrup, oral tablet
Guaifenesin is generally well tolerated.[Ref]
Nervous system side effects of codeine have included mental and respiratory depression, stupor, delirium, somnolence, and dysphoria. An increased risk of falls and hip fractures has been associated with codeine therapy, particularly in the elderly. Nervous system side effects of guaifenesin have included dizziness and headache.[Ref]
Opioids may result in psychotic symptoms in some patients.
One retrospective study of elderly patients who sustained a hip fracture suggested that the relative risk of hip fracture was 1.6 in patients using codeine compared to age-matched non-users.[Ref]
Other side effects of codeine have included withdrawal symptoms after either abrupt cessation or fast tapering of narcotic analgesics, including codeine, and have included agitation, restlessness, anxiety, insomnia, tremor, abdominal cramps, blurred vision, vomiting and sweating.[Ref]
Cardiovascular adverse effects of codeine have included hypotension and dizziness.[Ref]
Hypotension is rare and has been reported most frequently with high doses of codeine.[Ref]
Gastrointestinal side effects of codeine have included nausea, vomiting, and constipation. Severe constipation and ileus resulting in colonic perforation have been also reported. Four cases of acute pancreatitis have been reported. Gastrointestinal side effects of guaifenesin have included upset stomach and vomiting with higher than recommended doses. Doses recommended for expectoration are rarely associated with gastrointestinal upset.[Ref]
Genitourinary side effects of codeine have included urinary retention.[Ref]
Dermatologic side effects of codeine have included rash. Codeine-induced rash may be related to direct stimulation of histamine release. There are also case reports of severe scarlatiniform eruptions. Dermatologic side effects of guaifenesin have also included rash.[Ref]
Renal side effects of codeine have included acute renal failure (which may respond to naloxone therapy).[Ref]
Immunologic side effects of codeine have included one study of a patient with exercise-induced anaphylaxis and three control subjects. This study found a correlation between codeine wheal size and recent exercise.[Ref]
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19. Hill SA, Quinn K, Shelly MP, Park GR "Reversible renal failure following opioid administration." Anaesthesia 46 (1991): 938-9
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