By Paul Norio Morton, MD, FAAOS, FAAHKS
Board-certified orthopedic surgeon · Hip & knee specialist · Updated

Why constipation can happen after hip or knee replacement
Surgery changes several parts of your normal routine at once. Opioid pain medicines slow movement through the digestive tract. Anesthesia, nausea medicines, iron supplements, lower fluid intake, a smaller appetite, and less walking can add to the effect. Travel between islands or a long ride home may also disrupt meals, hydration, and bathroom habits.
Constipation does not mean only going fewer times. Hard or dry stool, straining, painful bowel movements, or feeling that stool has not passed completely also count. The National Institute of Diabetes and Digestive and Kidney Diseases lists narcotic pain medicines, dehydration, low activity, and diet changes among common causes. Review the NIDDK symptom and cause guide.
Make a bowel plan before surgery
Tell the surgical team what is normal for you and whether you have chronic constipation, irritable bowel syndrome, prior bowel obstruction, kidney or heart disease, fluid restrictions, or previous problems with laxatives. Bring a complete list of prescription medicines, over-the-counter products, vitamins, iron, calcium, and supplements. Several of these can affect bowel function or change which treatment is safest.
Your written discharge instructions should be the starting point. The JRH medication guide after joint replacement explains how the pain-control plan fits together. Do not stop a prescribed medicine, including an opioid, blood thinner, or iron supplement, without guidance. Instead, ask whether the dose or bowel regimen should be adjusted.
Start prevention on the first recovery day
Follow the bowel medicines in your discharge plan from the time instructed rather than waiting until several uncomfortable days have passed. Keep a simple record of bowel movements and the products you take. This is especially useful when a family member is helping with medications.
Drink regularly if you have not been placed on a fluid restriction. Water, broth, and other nonalcoholic fluids may help keep stool softer. Patients with heart failure, kidney disease, dialysis, or a prescribed fluid limit should follow their clinician's target rather than increasing fluids on their own. Limit alcohol during recovery, particularly while taking pain medicine.
Food and movement help, but pacing matters
As appetite returns, choose foods that provide fiber and fluid, such as oatmeal, beans, lentils, vegetables, pears, berries, prunes, or whole grains. Add fiber gradually. A sudden large increase can cause gas and bloating, and fiber without enough fluid may be unhelpful. If you have severe abdominal pain, vomiting, marked swelling, or cannot pass gas, do not try to fix the problem with more fiber. Seek medical guidance.
Short, frequent walks support circulation, joint recovery, and normal bowel activity. Follow your assistive-device and weight-bearing instructions. The knee replacement recovery timeline describes how walking and activity usually progress. Hip replacement patients should use the same principle of safe, frequent movement while following their own precautions.
Understand the main types of constipation medicine
Postoperative bowel plans often use one or more over-the-counter medicines, but the right product depends on your health, current medicines, and symptoms. Osmotic laxatives draw water into the bowel. Stimulant laxatives encourage bowel contractions. Stool softeners change stool consistency. Fiber supplements add bulk and require adequate fluid.
Do not assume that more products will work better. Combining medicines can cause cramping, diarrhea, dehydration, or electrolyte problems. Magnesium-containing laxatives may be unsafe for some people with kidney disease. Rectal products and enemas are not appropriate for every patient. Use the exact plan from your surgical or medical team, follow product directions, and ask a pharmacist or clinician before adding another agent.
Opioids deserve special attention
The American Association of Hip and Knee Surgeons notes that constipation is a common opioid side effect after hip or knee surgery. Take an opioid only as prescribed and use the lowest amount that makes recovery activities manageable. Do not abruptly change a long-term opioid regimen without the prescribing clinician.
For opioid-induced constipation, the American Gastroenterological Association recommends traditional laxatives as first-line treatment. Prescription medicines that specifically block opioid effects in the bowel may be considered when appropriate treatment has not worked, but they require a clinician's assessment. Read the AGA guideline summary.
When to contact the surgical or medical team
Call for guidance if bowel function is not responding to the written plan, symptoms are worsening, you are unsure which medicines can be combined, or constipation is preventing you from eating, drinking, walking, sleeping, or taking necessary medication. Contact the team sooner if you have a history of bowel obstruction, abdominal surgery, severe chronic constipation, kidney disease, or a fluid restriction.
Be ready to report your last bowel movement, whether you can pass gas, abdominal pain or swelling, nausea or vomiting, fluid intake, current opioid use, and every bowel product already taken. That information helps the clinician decide whether to change the plan or examine you.
Warning signs that need urgent evaluation
Constipation with constant or severe abdominal pain, repeated vomiting, a swollen or increasingly distended abdomen, fever, blood in the stool, rectal bleeding, or inability to pass gas should not be managed as routine postoperative constipation. NIDDK advises prompt medical evaluation for these symptoms. Sudden cramping with an inability to pass stool or gas can be a sign of intestinal obstruction.
A complete bowel obstruction is a medical emergency. Call 911 or seek emergency care for severe or rapidly worsening symptoms, fainting, confusion, trouble breathing, chest pain, or signs of shock. Do not drive yourself. See the MedlinePlus obstruction warning signs.
A simple recovery checklist
- Know your usual bowel pattern and record the last bowel movement.
- Follow the discharge bowel plan from the time instructed.
- Drink to your recommended fluid target and add fiber gradually.
- Walk short distances frequently within your joint-recovery restrictions.
- Take opioids only as prescribed and do not change essential medicines on your own.
- Ask before combining laxatives or using magnesium, rectal products, or enemas.
- Escalate early when the plan is not working, and treat obstruction warning signs as urgent.
Planning care in Hawaii
Patients in Honolulu, elsewhere on Oahu, Kona, Hilo, and across Hawaii should put bowel supplies, appropriate fluids, and easy high-fiber foods on the recovery checklist before surgery. Neighbor-island patients should also know whom to call after hours and where to seek urgent evaluation locally if travel to Oahu is not practical.
If you are preparing for hip or knee replacement and want a recovery plan that accounts for your medicines, medical conditions, and travel needs, schedule an orthopedic consultation with Joint Replacement Hawaii. Bring your current medication and supplement list and describe any prior constipation or bowel problems.
Sources and further reading
- American Association of Hip and Knee Surgeons: How to Relieve Pain After Hip Surgery
- American Association of Hip and Knee Surgeons: How to Relieve Pain After Knee Surgery
- NIDDK: Treatment for Constipation
- NIDDK: Symptoms and Causes of Constipation
- American Gastroenterological Association Institute Guideline on Opioid-Induced Constipation
- Randomized trial of bowel management before major joint arthroplasty
Medically reviewed by Paul Norio Morton, MD, FAAOS, FAAHKS. Last reviewed: . This article is for education only and isn’t a substitute for an exam and personalized advice — schedule a consultation to discuss your situation.
