According to the National Institute on Drug Abuse (NIDA), methadone is being successfully used to treat opioid, and especially heroin, addiction for more than 30 years. The drug is also widely prescribed to manage pain.

Now, here’s the irony of it all. NIDA acknowledges that there has also been an increase in the incidence of methadone-related adverse effects and overdose deaths in recent years. Fortunately, almost all of these are caused by misuse or abuse of the drug.

What are the long-term effects of methadone use?

Prolonged methadone use or abuse may lead to such effects as:

  • Tolerance to the drug
  • Physical dependence that causes withdrawal symptoms
  • Addiction that may stem from physical dependence
  • Respiratory problems
  • Cardiac problems
  • Impaired cognitive function
  • Menstrual problems in women

Knowing about the effects of methadone will help you be aware and more cautious.

The Short-Term Effects Of Methadone

Because methadone is a synthetic opiate, it mimics some of the effects of heroin by acting on the same receiving centers in the brain. However, it has a slow onset and acts over a longer period of time than heroin.

The short-term effects of methadone include:

  • Euphoria or “high” that opiate users typically crave for
  • Drowsiness
  • Insomnia
  • Weakness or fatigue
  • Dry mouth
  • Nausea and vomiting
  • Anxiety, restlessness, and nervousness
  • Intense sweating
  • Diarrhea
  • Constipation
  • Itchy skin
  • Loss of libido

The above-mentioned short-term side effects of methadone are bothersome but are usually not serious or life-threatening.

The Long-Term Effects Of Methadone

If taken as prescribed by a physician, methadone is safe. However, methadone treatment is usually prolonged, and the duration may vary from between a year to more than 20 years.

Prolonged use or abuse may produce one or more of the following side effects:

  • Tolerance that compels users to take more of the drug to experience the same degree of high
  • Physical dependence that causes withdrawal symptoms like stomach cramps, diarrhea, and bone and muscle pain
  • Addiction that may stem from physical dependence
  • Lung and respiratory problems
  • Cardiac problems
  • Neurological effects like decline in cognitive functionality
  • Menstrual problems in women

Continued use of methadone still keeps a user dependent on opioids.

But according to the Center for Substance Abuse Research at the University of Maryland, the long-term effects of methadone and especially its withdrawal symptoms are less harsh than those caused by heroin abuse. Besides, methadone has been proven to effectively reduce the incidence of heroin-overdose deaths, crime rates amongst heroin addicts, and spread of AIDS and other diseases caused due to using infected needles.

The Severe Side Effects Of Methadone

Misuse or abuse of methadone can trigger potentially fatal side effects very soon after taking the drug. These include:

  • Slow breathing
  • Long pauses between breaths
  • Breathlessness
  • Pounding heartbeat
  • Low blood pressure
  • Swelling of the eyes, face, mouth, throat, or tongue
  • Dizziness or feeling light-headed
  • Fainting
  • Prolonged QT interval, a cardiac complication that can cause irregular heartbeat, dizziness, fainting, or sudden death
  • Seizures
  • Hallucinations
  • Pinpoint pupils
  • Clammy or blue skin, bluish lips or fingernails

If left untreated, these side effects can send a person into a coma or worse, cause death.

Although some of these side effects are more commonly seen in the case of an overdose, the following groups of people are more prone to experiencing these effects:

  • Those who are not tolerant to the drug
  • Those who suffer from lung diseases like chronic obstructive pulmonary disease (COPD), emphysema, or chronic bronchitis
  • Those who suffer from cardiac conditions like irregular heartbeat
  • Those who are weak or malnourished
  • The elderly
  • Those who have taken the drug with other respiratory suppressants like alcohol, prescription or non-prescription medicines that contain alcohol, sedatives, sleeping pills, tranquilizers, muscle relaxants, or opioid-based pain medicine
  • Those who are suffering from mental illnesses and are on anti-anxiety or anti-depressant medication
  • Those who have taken it with other street drugs
  • Those who have a head injury or are suffering from any condition that increases the pressure in the brain

Other Effects Of Methadone On The Body And The Brain

A survey carried out amongst a cross-section of methadone clients discovered that they generally have poorer health than non-methadone users.

Can methadone use cause brain damage?

Yes, methadone can cause brain damage. Methadone mimics some of the effects of heroin by acting on the same receiving centers in the brain. The only difference is that its actions and onsets are slower than heroin. Symptoms may include confusion, disorientation, euphoria, depression and listlessness, and sleep disturbances.

Besides weakened respiratory and cardiac functions, methadone users may suffer from the following long-term medical conditions or disorders affecting various other major organs and systems of the body:

  • Whole Body: headaches, weakness, and water retention
  • Central Nervous System: confusion, disorientation, euphoria, depression and listlessness, sleep disturbances
  • Endocrinal System: hypogonadism or low testosterone level, a condition that impairs growth and development in males during puberty
  • Gastrointestinal System: abdominal pain, constipation, dry mouth
  • Metabolic System: low potassium or magnesium levels, weight gain
  • Blood: low platelet count that causes the blood to clot slowly after an injury, bruising, internal bleeding
  • Kidneys: urine retention, difficulty urinating
  • Reproductive System: reduced sexual drive, reduced sperm production, abnormal absence of menstruation in women
  • Skin: rashes, hives, severe itching that can lead to sores

Not all methadone users exhibit the adverse effects of the drugs to the same degree. According to a report published by the Washington University in St. Louis, people react differently to methadone depending on their genetic makeup. Physiological differences especially, impact the rate at which the drug is cleared from the body. So in some people, methadone may remain in their bodies while they take their next dose. Over time, this may cause a toxic buildup of the drug.

Methadone accumulation may cause the following effects:

  • Respiratory depression that manifests as slow breathing or difficulty breathing
  • Low levels of oxygen in the blood
  • Depression of the central nervous system

These symptoms of overdose manifest gradually, making methadone accumulation a potentially fatal side effect in some people.

In addition to the physical symptoms, a long-term methadone use can affect the brain and impair certain mental processes. Methadone acts on the nerves, cells, and neurotransmitters especially in the hippocampus and frontal region of the brain. The effects include:

  • Mood disturbances that range from euphoria to depression, especially when methadone reserves in the body run low
  • Delayed responses and reactions
  • Learning difficulties
  • Problems with memory

The Effects of Methadone on the Developing Fetal Brain and Babies Born to Mothers Taking Methadone

NIDA reports that there has been an increase in the number of pregnant women abusing heroin. Methadone is often administered to treat heroin addiction in pregnant women. But methadone can cross the placenta and get absorbed in the blood and tissues of the fetus.

Can Pregnant Women Take Methadone?

No, pregnant women should not take methadone. Methadone can harm a developing fetus, as it can cross the placenta and be absorbed in the blood and tissues of the fetus. Methadone disrupts the developmental process of the brain and its signal transmissions between cells.

Even therapeutic doses of methadone that do not harm the mother can adversely affect the developing fetal brain in the following ways:

  • Disrupt the normal pattern of signal transmission between brain cells
  • Disrupt the normal development of the brain and its processes

Babies born to mothers taking methadone can exhibit neonatal abstinence syndrome (NAS). They may show methadone withdrawal symptoms, which include:

  • Abnormal sleeping patterns or difficulty sleeping
  • Irritability
  • Hyperactivity
  • High-pitched crying that indicates distress
  • Vomiting
  • Diarrhea
  • High systolic blood pressure that suggests dysfunction of the autonomic nervous system
  • Inability to gain weight
  • Uncontrollable shaking of one or more parts of the body

Some of these effects can be life-threatening. The severity of the symptoms is directly proportional to the dose and duration of the methadone therapy.

The findings from a study at the University of Maine suggest that prenatal exposure to methadone is not always harmful to the baby if the therapy is well-managed. However, babies born to mothers whose doses were increased frequently during pregnancy exhibited the following adverse long-term effects:

  • Delays in standing up and walking
  • Problems in attention span
  • Problems with working memory
  • Difficulty learning languages and other skills
  • Problems controlling their behavior
  • Problems regulating emotions

These effects impact the performance of the children in school and their ability to relate to and interact with their peers.

A baby can exhibit the adverse effects of methadone if his mother starts to take methadone while breastfeeding. Methadone can pass into the body of the infant through breast milk. The signs that the drug is affecting the baby’s body are:

  • Unusual sleepiness
  • Difficulty breathing
  • Difficulty feeding
  • Limp body

The Substance Abuse and Mental Health Services Administration (SAMHSA) declares that methadone is safe if used appropriately. However, the SAMHSA has also issued advisory guidelines to help healthcare professionals administer methadone safely, and recognize the adverse effects and early warning signs of an overdose. The adverse effects of methadone warrant such precautions.