Relcof C Side Effects
Generic Name: codeine / guaifenesin
Note: This page contains side effects data for the generic drug codeine / guaifenesin. It is possible that some of the dosage forms included below may not apply to the brand name Relcof C.
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
The more commonly reported adverse effects of codeine include nausea, vomiting, and diarrhea. Guaifenesin is generally well tolerated.
Frequency not reported: CNS depression, lightheadedness, dizziness, sedation, headache, convulsions, weakness[Ref]
Frequency not reported: Tachycardia, bradycardia, palpitation, faintness, syncope, orthostatic hypotension, circulatory depression
Frequency not reported: Nausea, vomiting, constipation, biliary tract spasm, increased colonic motility, toxic dilation
Frequency not reported: Abdominal pain (upper), diarrhea, nausea, vomiting[Ref]
Frequency not reported: Oliguria, urinary retention, antidiuretic effect[Ref]
Codeine-induced rash may be related to direct stimulation of histamine release.[Ref]
Frequency not reported: Rash
Frequency not reported: Rash[Ref]
Frequency not reported: Pruritus, giant urticaria, angioneurotic edema, laryngeal edema
Frequency not reported: Hypersensitivity reactions (pruritus, urticaria)
Frequency not reported: Visual disturbances
Frequency not reported: Euphoria, dysphoria, transient hallucination, disorientation
Frequency not reported: Respiratory depression[Ref]
Respiratory depression and death have occurred in children who received codeine in the postoperative period following tonsillectomy and/or adenoidectomy. Further investigation has shown these patients to be ultra-rapid metabolizers of codeine. Children with obstructive sleep apnea who are treated with codeine appear to be particularly sensitive to the respiratory depressant effects of codeine.[Ref]
1. de Groot AC, Conemans J "Allergic urticarial rash from oral codeine." Contact Dermatitis 14 (1986): 209-14
2. "Product Information. Robitussin (guaifenesin)." Wyeth-Ayerst Laboratories, Philadelphia, PA.
3. Gonzalogarijo MA, Revengaarranz F "Fixed drug eruption due to codeine." Br J Dermatol 135 (1996): 498-9
4. US Food and Drug Administration "FDA News Release: FDA requires strong warnings for opioid analgesics, prescription opioid cough products, and benzodiazepine labeling related to serious risks and death from combined use. Available from: URL: http://www.fda.gov/NewsEvents/Newsroom/PressAn" ([2016, Aug 31]):
It is possible that some side effects of Relcof C may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.
More about Relcof C (codeine / guaifenesin)
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- Drug class: upper respiratory combinations