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Trade/other name(s): Capital and codeine; Codrix; Codeine as a sulfate or phosphate; Fioricet with codeine; Fiorinal with codeine; Phrenilin with caffeine and codeine, Soma Compound with codeine; Synalgos DC; Promethazine and codeine syrup; Promethazine, phenylephrine and codeine; and Tylenol with Codeine are just some of the medicines that contain codeine. This information pertains only to codeine; for information on aspirin or acetaminophen, see those titles.

Why would this drug be used?

Codeine relieves mild to moderate pain, and is frequently used along with other drugs such as acetaminophen or aspirin to boost its effects. It also helps control cough, and is sometimes combined with other medicines to treat the symptoms of respiratory infections.

How does this drug work?

Codeine is an opioid analgesic that is something like morphine, and the body transforms some of the codeine into morphine. It binds to opioid receptors in the central nervous system, which changes the perception of pain as well as the emotional response to it.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have any medical conditions such as kidney disease, liver disease (including hepatitis), low thyroid function, or Addison's disease (low adrenal function). These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you have trouble passing urine, a narrow urethra, or if you have an enlarged prostate. Codeine can make it harder to urinate.
  • If you have ever had a seizure, head injury, or if you have had problems with pressure, infection, or a tumor in your head or brain. Codeine can raise your risk of seizures.
  • If you have low blood pressure. Codeine can cause or worsen this.
  • If you have asthma, emphysema, chronic bronchitis, sleep apnea, or other breathing problems. Codeine can make them worse.
  • If you have had abdominal pain, pancreatitis, or any disorder involving slowed or blocked intestines, such as paralytic ileus. Codeine can worsen these problems.
  • If you or close family members have had fast or intense responses to codeine in the past (for example, severe sleepiness, trouble breathing, or confusion, that might have looked like an overdose even though only a single dose was taken).
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of harm to the fetus if a woman takes this drug during pregnancy, especially later in pregnancy.
  • If you are breastfeeding. This drug passes into breast milk and can affect the baby (see “Precautions” below).
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Medicines or substances that slow down the brain or nervous system, such as these, can cause worse side effects if taken with codeine:

  • Anti-anxiety drugs (tranquilizers or sedatives)
  • Sleeping pills
  • Muscle relaxers
  • Barbiturates
  • Anti-seizure medicines
  • Other opioid drugs such as morphine
  • Anesthetics
  • Tricyclic antidepressants such as amitriptyline, desipramine, doxepin, imipramine, nortriptyline
  • Anti-psychotic drugs
  • Certain anti-nausea medicines – phenothiazines such as promethazine (Phenergan) and prochlorperazine (Compazine)
  • Alcohol

Some of these drugs can cause slowed breathing, low blood pressure, extreme sleepiness, coma, or even death if taken with codeine.

Older antidepressants called MAOIs, such as phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), or selegiline (Emsam) may cause coma, slow or shallow breathing, low blood pressure, excitability, seizures, or shock if codeine is given within 2 weeks of the last MAOI dose. The antibiotic linezolid (Zyvox) and the dye methylene blue, which are both given in the vein, also act as MAOIs and interact in a harmful way with this drug.

Certain drugs for allergies, bowel spasms, overactive bladder, Parkinson’s disease, muscle spasms, and breathing problems can raise the risk of bowel blockage and trouble passing urine if taken with codeine. Tricyclic antidepressants (see above) can do the same thing.

SSRI antidepressants such as fluoxetine (Prozac), paroxetine (Paxil), duloxetine (Cymbalta), and others may affect your response to codeine. Anti-seizure drugs, drugs to treat TB, quinidine (a heart rhythm drug), and St. John’s wort may also change codeine’s effects. Your doctor may want to watch you more closely if you are taking any of these drugs while on codeine.

Buprenorphine (Subutex, Suboxone), butorphanol (Stadol), nalbuphine (Nubain), and pentazocine (Talwin, Talacen) can make codeine less effective or stop its action altogether. This can cause serious withdrawal very quickly if you have taken the codeine for some time.

Check with your doctor, nurse, or pharmacist about whether other medicines, vitamins, herbs, and supplements can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Codeine can be taken as a pill, capsule, or liquid by mouth. It is often taken with acetaminophen or aspirin to make it work better (this can be in the same pill, capsule, or liquid as the codeine). The medicine is usually taken every 3 to 4 hours as needed for pain. Your dose will depend on how well the medicine controls your pain.

Take this drug exactly as directed by your doctor. Don’t change your dose unless the doctor tells you to. If you are unsure about the instructions, ask your doctor or nurse to explain them to you.

Keep it in a tightly closed container away from heat and moisture and out of the reach of children, pets, and others. Do not allow other people to take your medicine. Flush unused codeine down the toilet as soon as possible.


Many forms of codeine are combined with acetaminophen (Tylenol) or aspirin. Check with your doctor, nurse, or pharmacist about what else is in your codeine prescription before you take non-prescription medicines for pain, fever, colds, or flu. Many of these remedies also have acetaminophen or aspirin, and you can get too much of them without knowing it. Overdoses of either drug can cause harm or death.

People who are allergic to sulfites or aspirin should check with their pharmacist to find out if their codeine pills contain sulfites or aspirin.

This medicine can cause drowsiness and lightheadedness. Do not drive, operate machinery, or perform other activities that require you to be alert until you know how you react to this medicine.

Codeine can make you feel dizzy or faint, and increase your risk of falling. Be careful getting up, changing position, or walking. Start slowly and hold onto something or someone to keep you steady. If you feel lightheaded or dizzy, it may help to lie down. It is best to have a responsible adult with you after starting the codeine and after any increase in dose, until you know how you will respond to it.

Since codeine affects the central nervous system, do not take other drugs or substances that slow down the brain or nervous system such as alcohol, sedatives, muscle relaxers, and sleeping medicines (see “Interactions with other drugs”) unless your doctor tells you to do so.

Call your doctor right away if you have trouble breathing, get short of breath, get confused, feel very drowsy, or start seeing or hearing things that aren’t there. These may be signs your dose is too high, your body is changing codeine to morphine too quickly, or that you might have gotten an accidental overdose of the medicine.

Talk to your doctor or nurse about using the smallest effective dose to reduce side effects and the development of tolerance and physical dependence. Tolerance means that larger doses are needed to get the same pain relief. Physical dependence means that the body goes into withdrawal if drug is suddenly stopped. Both happen normally when strong (opioid) medicines are taken over several weeks to treat chronic pain. But this is different from addiction, which starts when the drug is taken for pleasure rather than pain relief.

If you have chronic cancer pain, talk to your doctor or nurse about taking your pain medicines on a regular schedule to keep it from worsening. If you wait until the pain is bad, it takes more medicine to get it under control. If pain comes back between doses, talk to your cancer team about changing your medicine or adding an extra one for “breakthrough” pain.

Most cancer pain can be controlled. Keep your doctor or nurse informed about how well your pain medicines are working and any side effects you are having. Your cancer team may need to adjust your medicines several times before they find the medicines that work best for you. Do not adjust your dose without talking to your doctor or nurse.

Constipation is a very common side effect of taking opioid pain medicines. While you’re taking codeine, your doctor or nurse will likely recommend that you take medicines such as stool softeners, bulk-forming agents, and/or laxatives as needed to have regular (daily) bowel movements. Talk to your nurse or doctor about this when you first start this medicine. Drink plenty of fluids throughout the day, and try to eat foods high in fiber such as whole grains, bran, fruits, and vegetables. Call your doctor or nurse right away if you have not moved your bowels in 2 days.

If you have an allergic reaction, with symptoms like trouble breathing, itchy welts on your skin, or swelling in your mouth or throat, get emergency help right away.

Call your doctor or nurse right away if you have trouble passing your urine, trouble walking, vision problems, fainting, trouble swallowing, or other problems.

If you are having any kind of surgery or medical or dental procedure, be sure to tell the doctor or dentist that you are using this medicine.

Do not stop taking this medicine without talking to your doctor or nurse. If it is stopped too quickly or the dose reduced too much, you can have withdrawal symptoms. When no longer needed, this drug should be stopped gradually with the help of your doctor.

This drug is a controlled substance, and may be habit forming. Do not allow others to take your medicine. A person who has taken codeine for some time often needs large doses for pain relief, while the same amount could quickly kill someone else.

In some people, the body metabolizes (changes) codeine to morphine very quickly. This can have strong or even overdose-like effects, even though a standard codeine dose was taken. Other people can’t change the drug to morphine well, so that it doesn’t help their pain much. Tell your doctor if you have too much effect or too little relief from codeine.

Women who are breastfeeding while taking this drug should watch their babies closely. If you notice the baby is more sleepy than usual, has trouble breastfeeding or breathing, or seems limp, talk to the baby’s doctor or call 911 right away.

If you think you or someone else may have taken an overdose of codeine, get emergency help right away. Symptoms of codeine overdose may include extreme drowsiness, slow heart beat, slow or irregular breathing, cold clammy skin, or coma. Codeine overdose may cause the heart or breathing to stop. Contact the pharmacy to learn if other drugs were combined with the codeine, since an overdose could have delayed effects (if it contains acetaminophen, for example) and need special treatments.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • Drowsiness*
  • Sedation*
  • Mood changes, including happiness, irritability, agitation, or depression
  • Dizziness or lightheadedness*
  • Constipation*
  • Dry mouth

Less common

  • Mental clouding, confusion*
  • Nausea
  • Vomiting
  • Low blood pressure, which can cause dizziness or fainting when sitting or standing*
  • Shortness of breath
  • Flushing
  • Itching
  • Sweating
  • Decreased heart rate
  • Trouble urinating*
  • Trouble breathing*
  • Abdominal pain*


  • Seizures
  • Tiny pupils in eyes
  • Slow breathing*
  • Ruptured bowel from constipation
  • Decreased sexual ability
  • Decreased sexual interest
  • Withdrawal symptoms if dose is reduced too quickly after taking it a few weeks*
  • Allergic reaction with shortness of breath, itching skin welts, dizziness, or swelling in mouth or throat*
  • Death due to overdose or rapid metabolizing of a single dose, or taking it with drugs that intensify the effects of codeine

*See “Precautions” section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984 (FDA cannot verify dates of drugs approved before 1984).

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 06/27/2013
Last Revised: 06/27/2013