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Endacof-C Side Effects

Generic name: chlorpheniramine / codeine

Medically reviewed by Last updated on Oct 1, 2023.

Note: This document contains side effect information about chlorpheniramine / codeine. Some dosage forms listed on this page may not apply to the brand name Endacof-C.

Applies to chlorpheniramine / codeine: oral tablet extended release.


MISUSE OF THIS MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH. Keep the medication in a place where others cannot get to it.

Do not give this medicine to anyone younger than 12 years old, or anyone under 18 who recently had surgery to remove the tonsils or adenoids.

Fatal side effects can occur if you use this medicine with alcohol, or with other drugs that cause drowsiness or slow your breathing.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Opioid medicine can slow or stop your breathing, and death may occur. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.

Stop using this medicine and call your doctor at once if you have:

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Serious side effects may be more likely in older adults and those who are debilitated.

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to chlorpheniramine/codeine: oral liquid, oral suspension, oral suspension extended release, oral tablet, oral tablet extended release.


Frequency not reported: Peripheral edema, increased blood pressure, decreased blood pressure, tachycardia, chest pain, orthostatic hypotension, palpitations, syncope, prolonged QT interval, hot flush[Ref]

Nervous system

Frequency not reported: Coma, lethargy, serotonin syndrome, ataxia, sedation, headache, facial dyskinesia, lightheadedness, tremor, tinnitus, vertigo, impaired mental and physical performance, increased intracranial pressure, seizures[Ref]

Serotonin syndrome has been reported with concomitant opioids and serotonergic drugs.[Ref]


Frequency not reported: Abdominal pain, bowel obstruction, diarrhea, difficulty swallowing, gastro-esophageal reflux, pancreatitis, dry mouth, increase of serum amylase, paralytic ileus, biliary tract spasm (spasm of the sphincter of Oddi)[Ref]


Frequency not reported: Respiratory depression, bronchitis, cough, dry nose, dry throat, dyspnea, nasal congestion, nasopharyngitis, thickening of bronchial secretions, tightness of chest and wheezing, upper respiratory tract infection[Ref]


Adrenal insufficiency has been reported with opioid use, most often following greater than one month of use. Androgen deficiency has been reported with chronic opioid use.[Ref]

Frequency not reported: Adrenal insufficiency, androgen deficiency[Ref]


Frequency not reported: Flushing of face, hyperhidrosis, rash, pruritus[Ref]


Frequency not reported: Anaphylaxis[Ref]


Frequency not reported: Blurred vision, diplopia, miosis, visual disturbances[Ref]


The most common adverse events were sedation (somnolence, mental clouding, lethargy), impaired mental and physical performance, lightheadedness, dizziness, headache, dry mouth, nausea, vomiting, constipation, shortness of breath, and sweating.[Ref]


Frequency not reported: Death, fatigue, falling injuries, neonatal opioid withdrawal syndrome, drug overdose, obscured clinical course in patients with head injuries, neonatal opioid withdrawal syndrome[Ref]


Frequency not reported: Decreased appetite[Ref]


Frequency not reported: Agitation, anxiety, drug dependence, confusion, fear, depression, dysphoria, hallucinations, drug abuse, opioid withdrawal syndrome[Ref]


Frequency not reported: Agranulocytosis, aplastic anemia, thrombocytopenia


Frequency not reported: Arthralgia, backache, muscle spasm


Frequency not reported: Urinary tract infection, ureteral spasm, spasm of vesicle sphincters, urinary retention


1. (2010) "Product Information. Zodryl AC Adult (chlorpheniramine-codeine)." codaDOSE Incorporated

2. (2016) "Product Information. Tuzistra XR (chlorpheniramine-codeine)." Vernalis Pharmaceuticals Inc

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.