Opiate Side Effects

General information about the drug

Physicians commonly prescribe opiates to treat moderate to severe pain because this group of drugs provides pain relief with relatively few side effects. Many opiates are derived directly from the poppy plant, which naturally produces analgesic substances such as codeine and morphine. Pharmacologists also produce synthetic and semi-synthetic opiates that act similarly to natural opiates.

Opiates, like all medicine, can cause side effects. Many people experience no, or very minor, side effects from opiates. Most side effects are not serious and disappear after taking the medication as prescribed by a physician. Some side effects are serious and require medical attention.

Abuse, Dependence and Addiction

Abuse, physical dependence or addictions are some of the possible side effects from taking opiates, especially if an individual uses opiates non-medically, which means to take a drug to get high or to treat an illness for which it was not prescribed. Snorting or injecting opiates intravenously increases the risk for dependence, addiction, side effects and infectious diseases caused by sharing needles.

The U.S. Drug Enforcement Agency, or DEA, classifies substances according to the potential for abuse. The DEA has classified many opiates as Schedule II narcotics, which means they carry a high potential for abuse and mental or physical dependence. Heroin is a Schedule I narcotic, which means it poses the most risk for abuse and dependence as compared to all other drugs, and that it offers no medicinal value.

To be physically dependent on opiates means the person will suffer unpleasant, flu-like withdrawal symptoms after the level of the drug drops in his system. This sudden decrease in opiate levels may be because either he has not taken enough opiates or he has taken a drug, such as naloxone, that reduces the amount of this drug in his system quickly.

Withdrawal symptoms include:

  • Abdominal Cramps
  • Agitation
  • Anxiety
  • Blurred Vision
  • Insomnia
  • Restlessness
  • Sweating
  • Tremor
  • Vomiting

Medical professionals use the term "opiates" or opioids to describe a large family of drugs that includes morphine, codeine, oxycodone, heroin, methadone and more. Pharmacologists frequently produce polydrugs that contain varying amounts of opiates mixed with other analgesics such as aspirin or acetaminophen. Opiates may cause certain side effects, and so can these other additives. Physicians and pharmacists are always glad to review possible side effects associated with opiates and other analgesics.

Side effects associated with opiate use usually decrease in intensity or stop altogether with continued use at proper doses. The most serious side effect is respiratory problem that may lead to stopped breathing, circulatory depression, dangerously low blood pressure and shock. Physicians should expect side effects and treat patients accordingly.

Respiratory depression, a common and potentially fatal side effect, is a condition where the lungs do not adequately exchange oxygen and carbon dioxide. Respiratory depression is characterized by slow or shallow breathing.

Overdose is a serious, potentially fatal side effect of opiate use. While overdose does not typically occur while taking opiates as prescribed, certain medical conditions may prevent an individual's body from excreting excess medication, leading to toxic levels of opiates in the body.

If you suspect that you or someone you know has taken an overdose of opiates, whether through prescribed or illicit use, contact your local emergency room or poison control center by calling 1-800-222-1222. Symptoms of overdose include:

  • Cold, Clammy or Blue Skin
  • Death
  • Excessive Sleepiness
  • Large or Small Pupils
  • Loss of Consciousness
  • Seizure
  • Slow, Shallow or Stopped Breathing
  • Slowed or Stopped Heartbeat

Emergency department doctors administer medications such as naloxone to reduce opiates to safe levels. Nurses monitor the patient for complications and administer emergency, life-saving care as necessary.

Common Side Effects

Continue taking prescription opiates but contact the prescribing physician if the following side effects become intolerable or if they do not go away on their own:

  • Blurred Vision
  • Constipation
  • Dry mouth
  • Feeling Anxious, Dizzy or Drowsy
  • Headache
  • Mild Nausea, Vomiting, Upset Stomach
  • Mood Changes
  • Ringing in the Ears

Serious Side Effects

Some side effects are serious or life threatening, requiring the immediate attention of a medical professional. Stop taking opiates immediately and contact a doctor if you experience serious side effects, including:

  • Shallow Breathing
  • Slow Heartbeat
  • Feeling Lightheaded or Fainting
  • Confusion, Fear, Unusual Thoughts or Behavior
  • Seizures
  • Problems with Urination
  • Nausea, Stomach Pain, Loss of Appetite
  • Itching
  • Dark Urine, Clay-Colored Stools
  • Jaundice or Yellowing of the Skin or Eyes

Gender, race and increasing age influence the development of opiate side effects. Older individuals and patients with kidney problems may suffer from an accumulation of opiates in their system, increasing the risk for adverse effects and overdose. Nausea and vomiting is more common in women and blacks than men or whites.

Opiate Induced Hyperalgesia

Using opiates over a long period of time can lead to a paradoxical increase in pain. This is due to a phenomenon called hyperalgesia, which causes a heightened sensitivity to pain. Why this happens isn't clearly understood. Recognizing it can be tricky for doctors, and even trickier for patients. They may think their condition is worsening or that their medication isn't working adequately.

The risk is that doctors and patients may think that the dosage of opiates needs to be increased. This can lead to serious problems including dependence and addiction. Opiates, which include codeine and morphine, are often used as part of a pain management program. Opioids are semi-synthetic and are synthesized from opiates. They include oxycodone and hydrocodone.

Opiate Risks Are Real And Can Be Life Threatening

These narcotic medications have the ability to be habit forming and are subject to abuse. Long-term use and escalation of dosages can lead to problems with opiate dependence and opiate addiction.

Hyperalgesia can occur when an increased use of opiates leads to a reduced tolerance for pain. A person can become quickly tolerant to opiates and opioids, which may also lead them to increase their dosage. Some may even take more medication than what's prescribed. Both of these scenarios are dangerous and can result in addiction, overdose or death.

What You Can Do If You Suspect You've Developed Hyperalgesia

A reduction in the pain threshold is serious and often difficult to recognize. Many people spend a great deal of time seeking medical help for a perceived worsening of symptoms or the perceived development of a new ailment.

The best thing you can do if you experience an increase in pain while taking opiates is to talk to your doctor. It's possible to adjust the dosage or switch medications. Some people describe the pain from hyperalgesia as being different from the pain they are being treated for. Some compare it to widespread sensitivity or to symptoms of opiate withdrawal. Others say that hyperalgesia can cause a relatively minor injury (from a cut for example) to hurt a lot worse than it would for someone who doesn't have this condition.

There has been much debate within the medical community as to whether hyperalgesia really occurs among those who take prescription painkillers. Some patients also doubt it's real. An increased level of pain can be confusing for people who are on medications designed to combat pain. A doctor can help you sort through these issues and changes can be made to offer relief.

By body system


Respiratory depression is a common and potentially fatal adverse reaction associated with all opiates. Respiratory depression is a condition where the lungs do not adequately exchange oxygen and carbon dioxide. Symptoms of respiratory depression include slow, shallow or stopped breathing. The individual may also show signs of cyanosis, or a bluish color around the eyes, lips and fingertips.

Respiratory depression is a serious condition requiring immediate medical care. Emergency department doctors and nurses will administer 1mg to 2mg of naloxone every five minutes as necessary to reduce the amount of opiates in the system. Physicians will also monitor the patient's vital signs and blood gasses and administer oxygen as necessary to help the patient breath. Life-saving measures will be taken as necessary, as respiratory depression is potentially fatal.


About 25 percent of opiate consumers experience nausea, and opiates commonly cause constipation. Rarely, patients have had trouble swallowing oxycodone pills, requiring surgery to correct the problem. Patients with unresolved gastrointestinal problems are at greater risk for digestive issues relating to opiate use.

Opiate Gastrointestinal Effects

People who take opiates for a prolonged period will likely experience secondary side effects, some which can be very unpleasant. Opiates are often used in medicine to control pain, but they are also indicated for cough and diarrhea suppression and to treat opiate addiction.

Side effects are inherent with many prescription drugs, but long-term opiate use can cause damage to different areas of the body. Gastrointestinal damage from opiates can develop for those who take these drugs for long periods of time and for those people who take opiates in high dosages. People who take these drugs recreationally or in an abusive manner are also at risk.

Long-term opiate use can create problems such as dependence, addiction, stomach inflammation, ulcers, abdominal bloating, chronic constipation that can progress and liver damage.

How Opiates Work to Disrupt the Gastrointestinal System

The way opiates affect the gastrointestinal system is complex. It is thought that peristaltic movements are diminished by the drugs. Peristalsis is the contraction and relaxation of smooth muscles responsible for moving food through the digestive tract.

These movements are responsible for moving food through the intestine. With regular opiate use, feces can become dehydrated. This makes the stool hard and can prevent the natural flow of waste. Hard stools can block the bowels and this can lead to compaction. In severe cases, bowels can rupture, leading to sepsis or death.

The constipating effects of opiates are well known. Their ability to slow movement in the intestinal tract is the reason that opiates are used in the treatment of diarrhea. Patients with chronic constipation may be advised by doctors to take a stool softener or laxative. Other advice often includes eating a high fiber diet, drinking plenty of water and exercising to stimulate intestinal movement.

Opiates are also known to cause dyspepsia, which is dysfunction of the digestion cycle. This indigestion can lead to bloating, belching, gas, burning sensations and "sour stomach." If you are experiencing any of these secondary effects while on opiate therapy, check with your doctor to find out what you can do.

Central Nervous System

Opiates cause sedation in 20 to 60 percent of consumers, usually worse with the first doses or dose increases. Opiates also cause decreased cognitive function, which means opiates make it hard to think straight, especially in patients with some sort of cognitive deficiency to begin with. These effects usually subside.


Taking large doses of opiates or using these drugs for a long time may result in physical dependence, which means the individual will suffer withdrawal symptoms if the opiates drop below a certain level in his system.


Taking large doses of opiates or using them for a long time increases the risk for addiction. Addiction is a disease of the central nervous system that results in certain behaviors, such as craving and drug seeking. The disease of addiction changes the way a person thinks, feels and behaves.

Some opiates, such as oxycodone, may cause hallucinations or paranoia. It may also result in psychosis, which is a loss of contact with reality.


Opiates rarely cause itching. Physicians may prescribe 25mg to 50mg of diphenhydramine to alleviate this adverse reaction.


Opiate use may result in increased liver enzymes, typically an indicator of liver disease.


Opiate use may cause a dangerous form of irregular heartbeat, known as a QTc prolongation. This class of drugs may also stimulate the production of histamines, which causes itchy, watery eyes.