Codeine has a risk for abuse and addiction, which can lead to overdose and death. Codeine may also cause severe, possibly fatal, breathing problems. To lower your risk, your doctor should have you take the smallest dose of codeine that works, and take it for the shortest possible time. Ask your doctor or pharmacist if you should have naloxone available to treat opioid overdose. Teach your family or household members about the signs of an opioid overdose and how to treat it. The risk for severe breathing problems is higher when you start this medication and after a dose increase, or if you take the wrong dose/strength. Taking this medication with alcohol or other drugs that can cause drowsiness or breathing problems may cause very serious side effects, including death. Also, other medications can affect the removal of codeine from your body, which may affect how codeine works. Be sure you know how to take this medication and what other drugs you should avoid taking with it. Get medical help right away if any of these very serious side effects occur: slow/shallow breathing, unusual lightheadedness, severe drowsiness/dizziness, difficulty waking up. Keep this medicine in a safe place to prevent theft, misuse, or abuse. If someone accidentally swallows this medication, get medical help right away. Children younger than 18 years should not use products that contain codeine. Some children are more sensitive to codeine and have had very serious (rarely fatal) breathing problems such as slow/shallow breathing (). The risk is greater in children who are obese or have breathing problems, or after certain surgeries (including tonsil/adenoid removal). Talk with your doctor or pharmacist about the risks and benefits of this medication.

Nausea, vomiting, stomach upset, gas, shaking (tremor), constipation, dry mouth, lightheadedness, dizziness, drowsiness, or trouble sleeping may occur. If any of these effects last or get worse, notify your doctor or pharmacist promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. To prevent constipation, eat dietary fiber, drink enough water, and exercise. You may also need to take a laxative. Ask your pharmacist which type of laxative is right for you. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: interrupted breathing during sleep (sleep apnea), mental/mood changes, fast/irregular heartbeat, increased thirst/urination, hearing changes (such as ringing in the ears), easy bruising/bleeding, heartburn, discomfort when swallowing, dark urine, yellowing eyes/skin, signs of kidney problems (such as change in the amount of urine), signs of your adrenal glands not working well (such as loss of appetite, unusual tiredness, weight loss). Get medical help right away if you have any very serious side effects, including: fainting, seizure, black stools, severe stomach/abdominal pain, vomit that looks like coffee grounds, trouble speaking, weakness on one side of the body. Codeine is changed into a strong opioid drug (morphine) in your body. In some people, this change happens faster and more completely than usual, which increases the risk of very serious side effects. Get medical help right away if you notice any of the following: slow/shallow breathing, severe drowsiness/difficulty waking up, confusion. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: fever, swollen lymph nodes, rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Some products that may interact with this drug include: acetazolamide, antacids, certain antibiotics (including penicillin, sulfonamides such as sulfamethoxazole), certain drugs used to treat gout (including uricosuric drugs such as probenecid, sulfinpyrazone), darunavir, dichlorphenamide, lithium, 6-mercaptopurine, methotrexate, methoxyflurane, mifepristone, naltrexone, other medications for pain (such as morphine, nalbuphine, pentazocine), samidorphan, sodium oxybate. This medication may increase the risk of bleeding when taken with other drugs that also may cause bleeding. Examples include anti-platelet drugs such as clopidogrel, "blood thinners" such as dabigatran/enoxaparin/warfarin, among others. This drug can speed up the removal of other drugs from your body, which may affect how they work. Examples of affected drugs include doxycycline, estrogen, felodipine, lonafarnib, quinidine, rilpivirine, tamoxifen, theophylline, certain beta blockers (such as metoprolol), corticosteroids (such as prednisone), among others. The risk of serious side effects (such as slow/shallow breathing, severe drowsiness/dizziness) may be increased if this medication is taken with other products that may also cause drowsiness or breathing problems. Tell your doctor or pharmacist if you are taking other products such as other opioid pain or cough relievers (such as morphine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine). Check the labels on all your medicines (such as allergy or cough-and-cold products, other headache medications) because they may contain aspirin, caffeine or ingredients that cause drowsiness. Certain beverages (such as coffee, colas, tea) may also contain caffeine. Ask your pharmacist about using those products safely. Check all prescription and nonprescription medicine labels carefully since many medications contain pain relievers/fever reducers (including aspirin, NSAIDs such as ibuprofen, ketorolac, naproxen). These drugs are similar to this medication and may increase your risk of side effects if taken together. Ask your doctor or pharmacist for more details. Other medications can affect the removal of this product from your body, which may affect how this product works. Examples include azole antifungals (such as ketoconazole), bupropion, fluoxetine, macrolide antibiotics (such as erythromycin), HIV medications (such as ritonavir), paroxetine, rifamycins (such as rifabutin, rifampin), certain drugs used to treat seizures (such as carbamazepine, phenytoin), among others. This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well. This medication may interfere with certain medical/lab tests (such as fasting blood glucose, cholesterol levels, prothrombin time, urine 5-HIAA levels, amylase and lipase levels, certain urine glucose tests, dipyridamole-thallium imaging tests), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.