Meperidine Side Effects

Meperidine is available under the brand name formula, Demerol. Doctors prescribe meperidine to relieve moderate to severe pain.

Meperidine is available in several formulas, including tablets, syrup and with promethazine, an antihistamine that relieves runny nose, itching and watery eyes.

Like all medicine, meperidine may cause side effects. Many people experience no, or minor, adverse reactions resulting from meperidine use. Most of the side effects are not dangerous and disappear with continued use as prescribed. Some side effects are serious and require the immediate attention of a medical professional.

The adverse reactions to meperidine are typical of all opioids. Physicians should expect side effects and treat patients accordingly.

The most frequently experienced side effects are lightheadedness, dizziness, sedation, nausea, vomiting and sweating. Meperidine consumers who are not in significant pain or who are able to get up and walk around seem to experience these minor reactions more than people confined to a wheelchair or bed. Lying down seems to relieve these effects, as does reducing the dose.

The most serious side effect is respiratory problems potentially leading to stopped breathing, circulatory depression, dangerously low blood pressure and shock. Respiratory depression, another serious side effect associated with opioids such as meperidine, is a condition where the lungs do not adequately exchange oxygen and carbon dioxide. Symptoms of respiratory depression include slow or shallow breathing, unusual breathing patterns and a bluish tint around the eyes, lips and fingertips.

Abuse, Dependence and Addiction

Side effects of meperidine use include an increased potential for abuse, physical dependence or addiction. The U.S. Drug Enforcement Agency, or DEA, classifies drugs according to their potential for abuse. The DEA classifies meperidine as a Schedule II narcotic, which means it carries a high potential for abuse and mental or physical dependence. To reduce abuse, dependence and addiction, the DEA prohibits refills on schedule II drugs such as meperidine.

Physical dependence means you will suffer withdrawal symptoms after the level of opioid drops in your system, because either you have stopped taking meperidine or you have taken a medication to reduce the amount of this drug in your system rapidly. Withdrawal symptoms include:

  • Abdominal Cramps
  • Anorexia
  • Anxiety
  • Backache
  • Chills
  • Diarrhea
  • Increased Blood Pressure, Respiratory Rate or Heart Rate
  • Insomnia
  • Irritability
  • Joint Pain
  • Large Pupils
  • Muscle Pain
  • Nausea
  • Restlessness
  • Runny Nose
  • Sweating
  • Vomiting
  • Watery Eyes
  • Weakness
  • Yawning

Doctors diagnose a person as being addicted to meperidine if the patient uses drugs compulsively and for non-medical purposes, and if the person uses meperidine despite being aware of the harm it may cause.

Allergic Reaction

Anyone can have an allergic reaction to meperidine or any other medication. An allergic reaction is a serious medical emergency that requires prompt care. Stop taking meperidine and seek medical assistance right away if you think you are suffering an allergic reaction. Take your bottle of meperidine and all your medications with you to help the emergency department doctor understand which medication caused the reactions.

Symptoms of an allergic reaction include:

  • Rash
  • Hives
  • Itching
  • Difficulty Breathing
  • Tightness in the Chest
  • Swelling of the Mouth, Face, Lips or Tongue

Non-Serious Side Effects

Continue taking meperidine but contact the prescribing physician if your non-serious side effects become unbearable or if they do not disappear. Non-serious side effects vary slightly between meperidine preparations.

Meperidine, meperidine syrup and meperidine tablets may cause:

  • Constipation
  • Dizziness
  • Drowsiness
  • Flushing
  • Light-Headedness
  • Loss of Appetite
  • Nausea
  • Sweating
  • Vomiting

Taking meperidine with promethazine may not cause flushing but may result in dry mouth.

Serious Side Effects

Some adverse reactions are serious, requiring immediate medical attention. Immediately contact a doctor if you experience serious side effects.

Meperidine, meperidine syrup and meperidine tablets are associated with serious side effects such as:

  • Chest Pain
  • Confusion
  • Difficulty Urinating
  • Fainting
  • Fast, Slow or Irregular Heartbeat
  • Hallucinations
  • Mental or Mood Changes
  • Nausea or Vomiting
  • Numbness of an Arm or Leg
  • Seizure
  • Severe or Persistent Constipation or Stomach Pain
  • Severe or Persistent Dizziness or Light-Headedness
  • Severe or Persistent Drowsiness
  • Shaking
  • Slowed, Shallow or Difficult Breathing
  • Sudden Severe Headache
  • Uncontrolled Muscle Movements
  • Vision Changes

Meperidine with Promethazine is not associated with confusion, hallucinations or constipation but consumers are at increased risk for experiencing fever, chills, or persistent sore throat, rigid muscles and yellowing of the skin or eyes.


Overdose is a serious consequence of taking too much meperidine. If you think that you or someone you know has taken too much meperidine, seek emergency assistance immediately. Contact your local poison control center at 1-800-222-1222 or go to the nearest emergency room.

While at the hospital, you can expect emergency, life-saving treatments including activated charcoal, artificial respiration, fluids, laxatives, medicine to lower meperidine levels in the blood, medicine to reverse the effect of the meperidine or a tube through inserted the mouth into the stomach to wash out the stomach.

Overdose symptoms include:

  • Cold, Clammy Skin
  • Coma
  • Confusion
  • Extreme Drowsiness
  • Fainting
  • Muscle Weakness
  • Pinpoint Pupils
  • Shallow Breathing
  • Slow Heart Rate

By body system

Nervous system

Meperidine relieves pain and causes euphoria by acting directly on the brain and nervous system. As the result of this action, meperidine use results in certain adverse reactions affecting the nervous system.

The most serious is respiratory depression. Meperidine, like other opioids, affects the breathing center in the brain, sometimes causing the brain to "forget" how to breathe. Doctors may treat respiratory depression with naloxone, a medication that reduces opioids to safe levels.

Meperidine, as with other opioids, causes euphoria but it also causes its emotional opposite, dysphoria. More side effects include sleepiness, sedation and sweating. Other nervous system side effects include agitation, hallucinations, disorientation, mood changes and visual disturbances. Meperidine consumers may also experience weakness, headache, shakiness, muscle twitches or even seizures.


Meperidine may cause psychiatric side effects in some consumers. Psychiatric side effects include:

  • Fearfulness
  • Agitation
  • Paranoia
  • Hyper-vigilance
  • Auditory and Visual Hallucinations.


Meperidine, like other opioids, attaches to opioid receptors in the central nervous system and gastrointestinal tract. Because of this, opioids such as meperidine often cause side effects affecting the digestive tract including dry mouth and constipation. Constipation is less common with meperidine than with some other opioids.

Meperidine may cause a spasm in one of the ducts between the gall bladder and liver. Using meperidine may actually worsen biliary colic, or pain in the liver, gall bladder or ducts between them.

Other gastrointestinal side effects associated with meperidine include heartburn, nausea and vomiting.


Some consumers may be hypersensitive to meperidine. Hypersensitivity may lead to shock or anaphylaxis, which is a severe form of allergic reaction. Anaphylaxis usually occurs within moments of exposure but may happen as long as a half an hour or longer after taking meperidine. Seek help immediately if you think you or someone you know is suffering anaphylaxis.

Symptoms of anaphylaxis include hives along with itching, flushed or pale skin. You may feel a sensation of warmth. You may also feel like you have a lump in your throat, or that your throat is closing or your tongue is swelling up. This can lead to wheezing and trouble breathing. You may have a weak and rapid pulse, nausea, vomiting, dizziness or fainting. You might have a feeling of impending doom.


Anyone taking meperidine or other opioids for a long time may develop physical dependence or addiction to this drug. A physically dependent person will suffer withdrawal symptoms when the level of meperidine drops in his system. Doctors call this process detoxification, but it is also known as opioid abstinence syndrome or going through withdrawal.


Some people with a history of asthma have suffered bronchospasm after taking meperidine. There are case reports of bronchospasm occurring in patients with a history of asthma after receiving meperidine. Patients with underlying heart and lung diseases may also experience side effects after taking meperidine. Because of this and possible respiratory depression, meperidine should be used with caution in patients with serious breathing problems.


Patients who are under anesthesia, who are dehydrated, and who are receiving other medications may experience very low blood pressure after taking meperidine. Otherwise, low blood pressure is rarely associated with meperidine use.

Some meperidine consumers suffer phlebitis, which is inflammation in a vein, usually in the leg. Flushing or redness of the face, fast heartbeat, slow heartbeat, pounding heartbeat and dizziness is also associated with meperidine.


Meperidine may cause genitourinary side effects, including urinary retention.


Meperidine may cause dermatologic side effects including rash, itching and sweating. Other dramatic skin rashes, wheal and flare over the vein with. Intravenous injection of meperidine may cause dramatic skin rashes known as wheal and flare over the vein.


Meperidine may cause musculoskeletal side effects including muscle rigidity.