Methadone is a medication primarily used for managing severe, chronic pain and for treating opioid use disorder. It works by altering the way the brain and nervous system respond to pain. Despite its effectiveness, constipation is a very common and expected side effect for individuals taking methadone. This side effect can significantly impact a person’s comfort and quality of life.
How Methadone Affects the Bowel
Methadone, an opioid, causes constipation by interacting with opioid receptors in the gastrointestinal tract. When methadone binds to these mu-opioid receptors, it slows muscle contractions and movements in the stomach and intestines. This decreased intestinal motility means stool moves through the digestive system much slower.
This slowed transit time allows the colon to absorb more water from the stool. Increased water absorption leads to harder, drier, and smaller stools that are more difficult to pass. Opioids can also increase the tone of the anal sphincter, further complicating defecation. These combined effects contribute to the constipation experienced by individuals on methadone.
Managing Methadone-Induced Constipation
Managing methadone-induced constipation involves dietary and lifestyle adjustments. Increasing dietary fiber intake is recommended, aiming for 25 to 30 grams per day from fruits, vegetables, and whole grains. Adequate fluid intake, 8 to 10 glasses daily, helps keep stool soft and hydrated, making it easier to pass. Regular physical activity can stimulate bowel activity.
Over-the-counter remedies are used if lifestyle changes are insufficient. Stool softeners, such as docusate, increase water and fat in stool, making it softer. Stimulant laxatives, like senna or bisacodyl, increase intestinal contractions to move stool. Osmotic laxatives, such as polyethylene glycol (PEG) or magnesium hydroxide, draw water into intestines to soften stool and promote movements. Laxatives are recommended to start concurrently with opioid therapy to prevent constipation.
For cases not responding to these measures, prescription medications for opioid-induced constipation (OIC) are available. These include peripherally acting mu-opioid receptor antagonists (PAMORAs) like methylnaltrexone, naloxegol, and naldemedine. These medications block opioid effects in the gut without affecting pain relief, as they do not cross the blood-brain barrier. Lubiprostone is another option, increasing fluid secretion in the gastrointestinal tract. These prescription options should be discussed with a healthcare provider.
When to Seek Medical Help
Contact a healthcare provider if constipation becomes severe or is accompanied by other concerning symptoms. Seek medical attention if you experience severe abdominal pain, persistent bloating, or an inability to pass gas or stool. These symptoms could indicate a more serious condition, such as a bowel obstruction.
Other signs warranting medical consultation include vomiting, blood in the stool, or if constipation worsens despite consistent management efforts with diet, lifestyle changes, and over-the-counter remedies. Early discussion with a healthcare provider can prevent complications and ensure timely intervention.