What Causes Hard Stool?
What is hard stool?
Having a bowel movement should be relatively easy. However, in some people with constipation symptoms, stool becomes hard and pebble-like, making it more difficult and possibly painful to pass.
As waste products from digestion move through your gut, nutrients are extracted and absorbed and your intestines also gradually absorb water. Eventually this process produces stool in your large intestine (colon). In some people with constipation, the waste moves more slowly through the intestines, and your colon may absorb more water than usual. This can cause hard stools.
Hard stool can almost always be treated through changes in diet, over-the-counter stool softeners, or in some cases, prescription medications. It is important to distinguish between hard stool (hard consistency) and difficulty with passing stool (known as dyssynergic defecation) because these conditions are treated very differently.
1. Chronic constipation
A hard-to-pass stool does not mean your stool is hard. It is important to distinguish between having difficulty passing stool and having stool that is physically hardened. Sometimes these conditions can overlap, but individually they are treated differently. —Dr. Adam Pont
- Fewer than three bowel movements per week for several months
- Hard, dry stools
Chronic constipation is when you have fewer than three bowel movements a week for several months. When constipation is caused by waste products moving slower than normal through your gut (called slow-transit constipation), your body may absorb more water from the stool. This can produce harder stools.
Occasionally, not eating enough fiber can cause symptoms. In rare cases, dehydration may lead to constipation and hard stools, but this isn’t common in otherwise healthy people.
Initial treatment of constipation may include increasing fiber intake to 20g to 30g per day and staying hydrated. (Be sure to drink water when you are thirsty). Over-the-counter laxatives, such as psyllium (Metamucil), docusate (Colace), or polyethylene glycol (Miralax) may also help.
If these are not effective, your doctor may refer you to a specialist in digestive diseases (gastroenterologist) who may prescribe additional medications.
2. Irritable bowel syndrome
- Abdominal pain more than one day a week, usually associated with defecation
- Less frequent bowel movements (less than three times a week)
- Hard and pebble-like stools
Irritable bowel syndrome is a chronic disorder of the gut, mainly the large intestines. There are subtypes based on whether constipation or diarrhea are the main stool symptom. Irritable bowel syndrome with predominant constipation (IBS-C) is the type most likely to cause hard stools.
The cause of IBS-C isn’t yet known, but it’s thought to involve miscommunication between the gut and the brain. Prior intestinal infections, inflammation, or genetics may also play a role. In general, IBS is more common in women and people under the age of 50. It is more likely to occur in people with mood disorders (particularly anxiety and depression) or chronic pain syndromes, such as fibromyalgia syndrome or chronic fatigue syndrome.
IBS-C symptoms can usually be managed through lifestyle modification and medications. Your doctor may recommend avoiding certain food or drinks, increasing fiber intake, and getting regular exercise. It’s also helpful to manage stress, since stressors can sometimes make symptoms worse.
Your doctor may also recommend over-the-counter laxatives, or prescribe anti-spasmodics, certain antidepressants, or prescription laxatives.
Other possible causes
Several other conditions may also cause hard stool, though these are either rare or hard stool is not usually the defining symptom. They include certain metabolic and neurological diseases, certain medications (such as opioid pain medication), and cancer.
When to call the doctor
One way to easily describe your stools to your doctor is with the help of the Bristol Stool Scale, which classifies stool into 7 categories based on stool shape and consistency. Level 1 (separate hard lumps—like little pebbles) or level 2 stools (lumps stuck together in a sausage shape) are those generally associated with constipation symptoms. —Dr. Pont
You should always tell your primary care physician (at your usual check-ups) if you have changes in your stool frequency or consistency. However, if you have new persistent hard or pebble-like stools despite increasing your fiber intake and taking over-the-counter laxatives, you should schedule an appointment within 2 weeks.
Should I go to the ER for hard stool?
Isolated hard stool almost never requires emergency care. However, if your stool becomes so hard that you go at least 4 days without being able to have a bowel movement, you should go to the ER. You may be at risk for a fecal impaction (a blockage in your bowel).
Some people may see improvement in hard stools by increasing water intake. However, the vast majority of people with an intact thirst mechanism and without clinically significant dehydration (i.e. lightheaded, low urine output, mental status changes) won’t notice any effect from drinking more liquid—other than peeing more. —Dr. Pont
- Increase fiber consumption gradually through diet or fiber supplements.
- Drink more water.
- Try over-the-counter laxatives, such as docusate (Colace) or psyllium (Metamucil).
Other treatment options
For IBS-C, your doctor may prescribe any of the following medications:
- Anti-spasmodics (for abdominal pain and cramps): dicyclomine (Bentyl), hyoscyamine (Levsin, Levbid, Anaspaz), and peppermint oil (Colpermin, available over the counter)
- Antidepressants, such as amitriptyline. These can take up to several weeks to work.
For IBS-C (and occasionally for non-IBS constipation), your doctor may prescribe one of the following:
- Linaclotide (Linzess)
- Lubiprostone (Amitiza), though only used for female patients.
- Plecanatide (Trulance)
FAQs about hard stools
Here are some frequently asked questions about hard stools.
Does dehydration or not eating enough fiber cause constipation?
A lack of fluids in the body, or dehydration, does not usually cause constipation. Although drinking extra water may help soften stool.
Not eating enough fiber doesn’t usually cause constipation either. In some people with constipation and hard stools, increasing fiber intake or taking supplements may improve your symptoms. However, sometimes (and particularly if fiber intake is already adequate) adding fiber can actually worsen symptoms.
The best sources of fibers are fresh vegetables, fresh or dried fruits, and whole wheat and brown rice.
Can hard stools lead to hemorrhoids?
Maybe. Constipation is a possible risk factor for hemorrhoids, or enlarged rectal veins. Hemorrhoids can be painful and may bleed during a bowel movement. This blood often appears as either streaks on the stool, or blood on the toilet tissue after wiping. If you consistently see blood in your stool, you should see a doctor immediately for further evaluation.
What can I do for constipation when pregnant?
Ways to improve constipation during pregnancy include consuming plenty of fluids, eating a high-fiber diet, and maintaining a moderate amount of exercise. Talk to your doctor about taking laxatives approved for use during pregnancy if your constipation doesn’t improve.
Dr. Pont is currently a fellow in Gastroenterology at New York Presbyterian Hospital/Columbia, where he also completed his residency in Internal Medicine. Dr. Pont received his medical degree and PhD at the New York University School of Medicine. He earned his BS in Biological Systems Engineering at the University of Nebraska-Lincoln.