Ulcerative colitis is a long-term condition that causes inflammation and painful ulcers in the large intestine, affecting hundreds of thousands of people in the United States. While there is no cure, understanding the condition and working closely with healthcare providers can help people manage symptoms and live full, active lives.
What Is Ulcerative Colitis?
Ulcerative colitis is a type of inflammatory bowel disease, which refers to a group of lifelong conditions that cause swelling and inflammation in the intestines. The condition specifically affects the large intestine, also called the colon, and the rectum, which is the last part of the digestive tract where stool is stored before leaving the body. Unlike some other digestive diseases, ulcerative colitis causes inflammation only in the inner lining of the colon, creating open sores called ulcers that can bleed and produce pus.[1][2]
The disease typically starts in the rectum and spreads upward through the colon in a continuous pattern, meaning there are no healthy patches of tissue in between inflamed areas. This is different from Crohn’s disease, another form of inflammatory bowel disease, which can create scattered areas of inflammation throughout the digestive system. In ulcerative colitis, the inflammation is more superficial, confined to the mucosa and submucosa, which are the inner layers of the intestinal wall.[3]
Most people with ulcerative colitis experience what doctors call a relapsing and remitting course. This means they go through periods when symptoms flare up and cause significant discomfort, followed by periods of remission when symptoms disappear or become very mild. These remission periods can last for weeks, months, or even years. The unpredictable nature of these cycles can make daily life challenging, but with proper treatment and management, many people learn to control their symptoms and maintain long periods without active disease.[6]
How Common Is Ulcerative Colitis?
Ulcerative colitis is the most common form of inflammatory bowel disease worldwide. Research suggests that between 600,000 and 900,000 people in the United States are living with this condition. In some regions, particularly Northern Europe and North America, the numbers are even higher, with studies showing a prevalence of 156 to 291 cases per 100,000 people each year.[3][6]
The condition can develop at any age, but it most commonly appears in young adults. Most people receive their diagnosis between the ages of 15 and 30, though a second, smaller peak in diagnoses occurs in people over 60 years old. Both men and women are affected equally by ulcerative colitis, showing no significant gender preference in who develops the disease.[5]
There are notable patterns in who tends to develop ulcerative colitis. White people of European descent have the highest risk, especially those from Ashkenazi Jewish communities. Black people also show relatively high rates of the disease. Interestingly, people of Asian descent have historically had lower rates, though this is changing as the disease becomes more common in countries undergoing rapid westernization and lifestyle changes. In the United Kingdom, health organizations estimate that at least 1 in every 227 people has been diagnosed with ulcerative colitis, which amounts to approximately 296,000 individuals.[1][4]
What Causes Ulcerative Colitis?
The exact cause of ulcerative colitis remains unknown, which can be frustrating for people trying to understand why they developed the condition. However, researchers have identified several factors that appear to play important roles. The most widely accepted theory is that ulcerative colitis is an autoimmune condition, meaning the body’s immune system, which normally protects against harmful bacteria and viruses, mistakenly attacks healthy tissue in the colon.[4]
In a healthy person, the immune system recognizes harmless bacteria living naturally in the intestines and leaves them alone. But in someone with ulcerative colitis, the immune system appears to mistake these harmless bacteria for dangerous invaders. This triggers an inflammatory response, causing the body to attack the tissues of the colon itself. The result is the chronic inflammation and ulcers characteristic of the disease. However, scientists still don’t fully understand what causes this immune system malfunction in the first place.[1]
Most experts believe that ulcerative colitis develops from a combination of genetic and environmental factors working together. It’s not caused by a single gene or a single environmental trigger, but rather by multiple factors that interact in complex ways. Some researchers have also suggested that changes in the composition of gut bacteria, called the microbiota, and defects in the body’s ability to regulate immune responses in the intestinal lining might contribute to the development of the disease.[3]
Risk Factors
While anyone can develop ulcerative colitis, certain factors increase the likelihood of getting the disease. The most significant risk factor is having a family history of inflammatory bowel disease. If you have a first-degree relative, such as a parent, sibling, or child, with ulcerative colitis, you are four times more likely to develop the condition yourself. Overall, between 8% and 14% of people with ulcerative colitis have a family member with the disease, suggesting a strong genetic component.[3][6]
Ethnicity also plays a role in risk. Jewish populations have higher rates of ulcerative colitis compared to other ethnic groups. White people of European descent face elevated risk, as do Black individuals. Meanwhile, people from Asian backgrounds have traditionally had lower rates, though this is changing as these populations adopt more westernized lifestyles and diets.[1]
Age is another important factor, with most cases diagnosed in people between 15 and 30 years old. However, the disease can strike at any stage of life, and there is a second, smaller peak of new diagnoses in people over 60. Geographic location matters too, as inflammatory bowel disease is closely linked to westernized environments and lifestyles. The highest rates are found in Northern Europe and North America, suggesting that factors like diet, sanitation levels, and other aspects of modern life may influence disease development.[3]
Interestingly, there is some evidence suggesting that smoking may have a protective effect against ulcerative colitis, though researchers have not been able to confirm a direct relationship. This is unusual because smoking is harmful for most other health conditions, and it actually makes Crohn’s disease worse. Despite this potential association, no one recommends smoking as a prevention strategy due to its many other serious health risks.[3]
Symptoms of Ulcerative Colitis
The symptoms of ulcerative colitis can vary widely from person to person, depending on how much of the colon is affected and how severe the inflammation is. The main symptoms include recurring diarrhea, which may contain blood, mucus, or pus, along with stomach pain and an increased need to have bowel movements. These symptoms often develop gradually and may worsen over time if left untreated.[4]
One of the most distinctive and troublesome symptoms is an urgent, sudden need to empty the bowels. This urgency happens because the inflamed rectum cannot function properly. A healthy rectum is designed to stretch and store stool, as well as to sense what is inside and signal when it’s time to go to the bathroom. When the rectum is inflamed, it loses these abilities. It cannot stretch to hold stool, and it cannot properly sense what’s there. As a result, people with active ulcerative colitis may feel like they need to rush to the bathroom many times throughout the day, even though very little stool might come out each time.[14]
People with mild ulcerative colitis typically have four or fewer episodes of diarrhea daily. As the condition becomes more severe, the number of bowel movements increases, often to four or more times per day. The diarrhea frequently contains visible blood, and people may also notice mucus or pus in their stool. Severe abdominal cramping and pain often accompany these bowel movements, particularly in the lower abdomen.[5]
Beyond intestinal symptoms, many people experience systemic effects. Extreme tiredness, called fatigue, is very common and can be debilitating. Loss of appetite leads to weight loss in many cases. Some people develop a fever, particularly during severe flare-ups. A symptom called tenesmus, which is a constant feeling of pressure in the rectum and the sensation that you need to have a bowel movement even when your bowels are empty, can be especially uncomfortable.[4][5]
About 25% of people with ulcerative colitis eventually develop what doctors call extra-intestinal manifestations, meaning symptoms that affect body parts other than the colon. The most common of these is joint pain and swelling, which typically affects smaller joints on both sides of the body symmetrically. This joint pain usually gets better when the intestinal inflammation is treated. Other people may experience eye problems, such as red, burning, or itchy eyes. Skin issues can develop, including painful bumps, rashes, or ulcers. In rare cases, the liver may become inflamed.[5][9]
Complications
Ulcerative colitis can lead to serious complications, especially if inflammation is not controlled. The most severe complications can become life-threatening and require immediate medical attention. These include severe dehydration, which results from the colon’s reduced ability to absorb water combined with fluid loss during frequent trips to the bathroom. Severe bleeding from the rectum can occur when ulcers cause large amounts of blood to pass during bowel movements.[2]
A perforated or torn colon is another emergency complication. This happens when ulcers and chronic inflammation create a hole in the colon wall, allowing intestinal contents to leak into the abdominal cavity. An extremely rare but serious complication called toxic megacolon occurs when inflammation spreads to the deeper tissues of the intestines, causing such severe swelling that the colon stops working entirely. This form of the disease, known as fulminant ulcerative colitis, causes extremely severe symptoms and requires urgent hospital treatment.[2][5]
Long-term complications include an increased risk of developing bowel cancer. People who have had ulcerative colitis affecting a third or more of their colon for eight to ten years or longer face a higher risk of developing precancerous changes in the bowel lining. For this reason, doctors recommend regular bowel cancer screening through colonoscopy for people with long-standing disease. The frequency of screening depends on how long someone has had ulcerative colitis and how much of the colon is affected.[6][15]
Other complications can affect growth and development in children and young people with ulcerative colitis, including slower growth, lower weight gain than expected, short stature, and delayed puberty. Bone problems are common, with many people developing low bone mass, a condition called osteopenia, or more severe bone weakening called osteoporosis. This can happen both from the inflammation itself and as a side effect of steroid medications used to treat the disease. Different types of anemia, including iron-deficiency anemia and anemia of inflammation, are also common in people with ulcerative colitis.[6]
How the Body Changes in Ulcerative Colitis
Understanding what happens inside the body during ulcerative colitis helps explain why symptoms occur. The disease causes specific changes to the normal structure and function of the large intestine. In a healthy colon, the inner lining, called the mucosa, forms a protective barrier. This lining contains cells that absorb water and nutrients, produce protective mucus, and house immune cells that defend against harmful bacteria while tolerating beneficial ones.[2]
In ulcerative colitis, the immune system becomes overactive and attacks this inner lining. The inflammation that results is confined to the mucosa and the layer just beneath it, called the submucosa. Unlike Crohn’s disease, which can affect all layers of the intestinal wall, ulcerative colitis damage remains relatively superficial. However, this inflammation is continuous and diffuse, meaning it affects all the tissue in the involved area without leaving healthy patches in between.[3]
The inflammation causes the intestinal lining to become swollen, red, and fragile. Small ulcers develop, which are essentially open sores on the surface of the lining. These ulcers can bleed easily, which is why blood appears in the stool. The damaged lining also produces excess mucus and sometimes pus, which also pass in the stool. The inflammation makes the intestinal walls weaker over time, and in severe cases, this can lead to the walls wearing away completely.[1][2]
The disease typically begins in the rectum and spreads upward in a continuous fashion. Depending on how far the inflammation extends, doctors classify ulcerative colitis into different types. Ulcerative proctitis affects only the rectum. Proctosigmoiditis involves the rectum and the sigmoid colon, which is the lower, S-shaped part of the large intestine. Left-sided colitis affects the left side of the colon, while pancolitis involves inflammation throughout the entire colon. About 30% of adults have the entire colon affected when first diagnosed, while another 30% have only the rectum inflamed.[5][14]
The rectum’s dysfunction explains many symptoms. When the rectum is inflamed, it cannot stretch normally to store stool, cannot sense properly what’s inside, and cannot control its squeezing function effectively. This triple failure creates the urgent need to have bowel movements, the frequent trips to the bathroom with little result, and the feeling of incomplete evacuation that characterizes the disease. Because the inflamed tissue is so fragile and the ulcers bleed easily, even small amounts of stool passing through can cause bleeding and pain.[14]
Prevention
Because the exact cause of ulcerative colitis is unknown, there are no proven ways to prevent the disease from developing in the first place. Unlike some conditions where lifestyle changes or vaccinations can prevent disease, ulcerative colitis appears to result from a complex interaction of genetic predisposition and environmental factors that researchers don’t yet fully understand. However, for people already diagnosed with the condition, there are steps that can help prevent flare-ups and maintain remission.[3]
Managing stress may help reduce the frequency of symptom flare-ups. While stress does not cause ulcerative colitis, many people find that their symptoms worsen during stressful periods. Techniques for stress relief include regular exercise, which has been proven to reduce stress and improve mood. Relaxation techniques such as breathing exercises, meditation, and yoga can teach people to calm their body’s stress response. Maintaining good communication with family, friends, and healthcare providers helps prevent the isolation and frustration that can make stress worse.[15]
Dietary changes may help some people prevent flare-ups, although specific dietary triggers vary from person to person. Most doctors recommend that people with ulcerative colitis follow a healthy, balanced diet and drink plenty of fluids to avoid dehydration and ensure they get all necessary nutrients. Keeping a food diary can help identify which foods trigger symptoms and which ones are well tolerated. When a problematic food is identified through this careful tracking, it can be eliminated from the diet. However, it’s important not to eliminate entire food groups without talking to a healthcare provider, as this could lead to nutritional deficiencies.[15]
The most effective way to prevent complications of ulcerative colitis is to work closely with healthcare providers to keep the disease in remission using appropriate medications. Regular monitoring and adjusting treatment as needed helps prevent the serious complications that can develop from ongoing, uncontrolled inflammation. For people with long-standing disease, regular bowel cancer screening helps catch any precancerous changes early when they are easiest to treat.[6]
