Constipation in Parkinson’s Disease: Causes, Warning Signs and What Helps

Written and reviewed by Dr. Akbar Zaib, PhD in Neurosciences
Neuroscientist • Parkinson’s Researcher
Last updated: August 2026

---

Constipation in Parkinson’s disease is common, but it is often overlooked. It can cause bloating, discomfort and straining, and may even make Parkinson’s medication work less predictably.

Several practical changes to diet, fluid intake, movement and toilet habits may provide relief. However, constipation can have different causes, and some people may also need treatment or professional assessment. Here are five practical approaches that may help — and the warning signs you should not ignore.

---

---

Constipation is one of the most common non-movement symptoms of Parkinson’s disease. It may develop years before noticeable movement symptoms, and it can continue or become more troublesome as Parkinson’s disease progresses.

The problem is not always caused simply by eating too little fibre. Parkinson’s disease can affect the autonomic nerves that control the digestive tract, slowing the movement of stool through the colon. Reduced physical activity, inadequate fluid intake, difficulty coordinating the muscles used during a bowel movement, and certain medications may also contribute.

Constipation can cause abdominal discomfort, bloating, straining and a feeling that the bowel has not emptied completely. It may also interfere with how consistently oral Parkinson’s medication is absorbed. For this reason, persistent constipation should be discussed with a healthcare professional rather than accepted as an unavoidable part of Parkinson’s disease.

This article explains why constipation occurs, how to recognise it and which practical, evidence-based approaches may help. It also identifies warning signs that require prompt medical attention.

What does constipation mean?

Constipation does not simply mean going several days without a bowel movement. It can also involve:

• Fewer than three spontaneous bowel movements per week
• Hard, dry or lumpy stools
• Frequent straining
• Feeling that the bowel has not emptied completely
• Feeling that stool is blocked or difficult to pass
• Needing considerable time—or physical assistance—to empty the bowel

A person may therefore have constipation even when passing stool regularly. In Parkinson’s disease, the pattern can differ: some people experience slow movement of stool through the colon, while others have difficulty relaxing and coordinating the pelvic-floor muscles needed for evacuation. Some experience both.

Keeping a simple record of bowel frequency, stool consistency and straining can help a healthcare professional identify the likely problem and recommend appropriate treatment.

Why does constipation occur in Parkinson’s disease?

Constipation in Parkinson’s disease usually results from several factors acting together.

1. Slower movement through the colon

Parkinson’s disease can affect the autonomic and enteric nervous systems, which help control the digestive tract. As a result, contractions that move stool through the colon may become slower, allowing more water to be absorbed and making the stool harder.

2. Difficulty emptying the bowel

Some people have trouble coordinating or relaxing the pelvic-floor and anal muscles during a bowel movement. This can cause prolonged straining, incomplete emptying or a sensation of blockage—even when the stool is not particularly hard.

3. Reduced movement

Walking and other physical activity help stimulate normal bowel function. Slowness, stiffness, fatigue or balance difficulties can reduce activity and contribute to constipation.

4. Diet and fluid intake

Too little fibre or fluid can make stool more difficult to pass. Swallowing problems, reduced appetite, urinary concerns or difficulty preparing meals may also affect eating and drinking habits.

5. Medications and other health conditions

Anticholinergic medicines, some antidepressants, opioid painkillers, iron supplements and certain other drugs can worsen constipation. Parkinson’s medications should not automatically be blamed or stopped, however. A doctor or pharmacist should review the complete medication list and consider other possible causes, such as thyroid disorders or diabetes.

---

---

Why constipation should not be ignored

Persistent constipation can affect much more than bowel comfort. It may lead to:

• Abdominal pain, bloating and loss of appetite
• Painful straining or haemorrhoids
• Reduced sleep, activity and quality of life
• Faecal impaction, particularly in older or less mobile people
• Urinary symptoms caused by pressure from a stool-filled bowel

Digestive problems may also make the response to oral Parkinson’s medication less predictable. However, constipation is not necessarily the only cause of medication fluctuations; delayed stomach emptying, meal composition and disease progression can also contribute.

Treating constipation early is generally easier than managing severe stool retention or impaction. A noticeable change in bowel habits should therefore be discussed with a healthcare professional, especially when it persists despite basic dietary and lifestyle measures.

If your doses sometimes take longer to work, see our guide to Parkinson’s medication timing and delayed absorption.

Practical steps that may help

The best approach depends on whether the main problem is hard stool, slow bowel movement or difficulty emptying the bowel. However, the following measures are often a useful starting point.

1. Increase fibre gradually

Fibre helps retain water and add bulk to stool. Good sources include vegetables, fruit, beans, lentils, oats and whole grains. Increase it gradually, because a sudden large increase may worsen bloating—particularly if fluid intake is inadequate or bowel movement is very slow.

2. Drink enough fluid

Adequate fluid helps prevent stool from becoming hard. Water is generally the best choice. However, people with swallowing difficulties or medical conditions requiring fluid restriction should ask their healthcare team how much is appropriate.

3. Keep moving

Regular walking and other suitable physical activities may support bowel movement. Even brief periods of movement throughout the day can be useful when longer exercise sessions are difficult.

4. Establish a regular routine

Try sitting on the toilet at approximately the same time each day, preferably after breakfast or another meal, when the bowel’s natural activity is often stronger. Allow enough time, but avoid prolonged or forceful straining.

5. Improve toilet position

Placing the feet on a small, stable footstool can raise the knees above the hips and create a more favourable position for passing stool. Lean forward slightly, keep the abdomen relaxed and breathe normally rather than holding your breath.

These measures may take time to work. If constipation persists, becomes painful or repeatedly causes incomplete emptying, further assessment and treatment may be necessary.

When lifestyle changes are not enough

If diet, fluids, movement and routine do not provide enough relief, a healthcare professional may recommend additional treatment.

Review current medications

A doctor or pharmacist can identify medicines that may be contributing to constipation. Do not stop or change Parkinson’s medication without medical advice; the dose, timing or an accompanying medicine may instead need adjustment.

For a broader explanation of changing medication response, read what to do when Parkinson’s medication is not working as well.

Laxatives

Osmotic laxatives draw water into the bowel and soften the stool. Polyethylene glycol — also called macrogol — has shown benefit in a small randomized controlled trial involving people with Parkinson’s disease. Other laxatives may be appropriate depending on the symptoms, but frequent or prolonged use should be discussed with a healthcare professional.

Probiotics

Clinical trials in people with Parkinson’s disease suggest that certain probiotic or fermented-milk preparations may modestly improve bowel-movement frequency. However, probiotic products differ considerably, so results from one formulation cannot be applied to every supplement.

Pelvic-floor treatment

When stool reaches the rectum but remains difficult to pass, simply adding more fibre may not solve the problem. Assessment by a gastroenterologist or pelvic-floor specialist may identify a coordination disorder. Pelvic-floor therapy or biofeedback may then be more appropriate.

Persistent symptoms should be evaluated according to the type of constipation rather than treated through repeated trial and error.
problem.

When to seek medical advice

Contact a healthcare professional if constipation is persistent, worsening or repeatedly interferes with daily life. Medical assessment is particularly important if you experience:

• Blood in the stool or rectal bleeding
• Unexplained weight loss
• Persistent or severe abdominal pain
• Vomiting or a swollen abdomen
• Fever
• A sudden, unexplained change in bowel habits
• Very thin stools that continue over time
• Inability to pass stool or gas
• Leakage of liquid stool, which can sometimes occur around an impaction
• Constipation that does not improve with appropriate self-care

Severe abdominal pain, vomiting, marked swelling, or inability to pass stool or gas may indicate an obstruction or faecal impaction and requires urgent medical attention.

New bowel symptoms should not automatically be attributed to Parkinson’s disease. A clinician may need to rule out medication effects, metabolic conditions, colorectal disease or another underlying cause.

 A simple bowel-tracking checklist

Before speaking with your healthcare professional, record the following for one or two weeks:

• Date and time of each bowel movement
• Stool consistency—hard, formed, soft or watery
• Whether you had to strain
• Any feeling of blockage or incomplete emptying
• Abdominal pain, bloating or nausea
• Daily fluid and approximate fibre intake
• Physical activity
• Laxatives or supplements taken
• Recent medication changes
• Any relationship between constipation and Parkinson’s medication response

This short record can help distinguish infrequent bowel movements from an emptying difficulty and make the medical discussion more focused. The Bristol Stool Chart may also provide a consistent way to describe stool appearance.

Key takeaways

Constipation in Parkinson’s disease is common, but it should not be regarded as something that simply has to be endured. Parkinson’s disease may slow movement through the colon, interfere with the muscles required for emptying the bowel, and make contributing factors such as reduced activity or medication effects more important.

Gradually increasing fibre, drinking an appropriate amount of fluid, staying active, establishing a toilet routine and improving toilet position may help. When these measures are insufficient, treatment should be selected according to the type of constipation rather than through repeated trial and error.

Most importantly, persistent constipation, incomplete emptying or a significant change in bowel habits should be discussed with a healthcare professional. Seek urgent help for severe pain, vomiting, marked abdominal swelling, or inability to pass stool or gas.

---

Disclaimer: The information shared here should not be taken as medical advice. The opinions presented here are not intended to treat any health conditions. For your specific medical problem, consult with your health care provider.