Understanding Melanosis Coli: Causes, Diagnosis, and Reversibility
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Melanosis coli is a harmless, noncancerous condition in which the lining of the colon looks dark brown or black. It is usually caused by using certain stimulant laxatives for too long, it causes no symptoms, and it reverses once you stop the laxatives[1].
Quick Answer: What is melanosis coli?
Melanosis coli is a benign condition that darkens the colon lining from a buildup of the pigment lipofuscin, most often after prolonged use of anthraquinone laxatives such as senna. It causes no symptoms, is usually found during a colonoscopy and does not raise the risk of serious disease. It typically reverses within six to twelve months of stopping them. [1]
What the research says
Melanosis coli is reversible, and general measures are preferred. A comprehensive review notes that most studies show a significant correlation between anthraquinone laxative use and melanosis coli, that the condition is reversible, and that changing living habits is the preferred treatment, with no medical or surgical treatment needed in the absence of serious malignancy (Yang et al., Gastroenterol Hepatol, 2020 [2]).
Anthraquinone laxatives have not been proven to cause colorectal cancer, but the question is still being studied. A meta-analysis of 5 observational studies (from 8 identified) found an odds ratio of 1.41 (95% CI 0.94–2.11) for colorectal cancer with anthraquinone laxative use, which was not statistically significant. The authors concluded that the use of these laxatives cannot be linked to colorectal cancer, but that the trend justifies further high-quality studies (Lombardi et al., Phytother Res, 2022 [3]).
Melanosis coli may not be a precancerous lesion. In a retrospective cohort of 2,150 patients with melanosis coli and 39,630 controls, adenoma detection was higher in melanosis coli (30.34% vs 23.92%), while serrated polyp detection was lower (0.93% vs 1.58%). The authors concluded that melanosis coli may not be considered a precancerous lesion (Wang et al., Int J Colorectal Dis, 2023 [4]).
What Is Melanosis Coli?
Melanosis coli is a benign (noncancerous) condition that makes the inner lining of the colon darker than usual. Normally the lining is pink, but in melanosis coli parts of it can look dark brown or black. The discoloration is not caused by disease or tissue death. It comes from a pigment in the colon wall called lipofuscin[1].
The condition is usually found by chance during an imaging procedure such as a colonoscopy or flexible sigmoidoscopy done for another reason. The sight of a darkened colon can be startling, but melanosis coli is not serious and does not interfere with how your colon works[1].
A normal colon lining (left) compared with the dark pigmentation of melanosis coli (right).
What causes melanosis coli, and what are the risk factors?
Melanosis coli usually occurs in people who use certain laxatives for too long. The laxatives involved are stimulant laxatives that contain anthraquinones, organic compounds found in some plants. They can relieve constipation, but they should not be taken for longer than two weeks. Used for longer, they can damage the cells lining the colon. Those cells then release lipofuscin, which builds up and gives the lining its dark color. Once the laxatives are stopped, the lining usually returns to normal within six to twelve months[1].
Anthraquinone source | Description |
Senna | A widely used herbal stimulant laxative. |
Aloe | Often used in health supplements and laxatives. |
Cascara sagrada | Derived from the bark of the buckthorn tree. |
Rhubarb | The root of certain rhubarb species is used for its laxative properties. |
Buckthorn | A plant source of several traditional laxative preparations. |
Frangula | Another plant source of anthraquinones used in laxatives. |
Plants such as aloe, senna, and rhubarb contain anthraquinones, which can cause melanosis coli with long-term laxative use.
Less commonly, people develop melanosis coli without using laxatives. Other possible causes include[1]:
Chronic diarrhea.
Inflammatory bowel disease (IBD).
Irritable bowel syndrome (IBS).
Vitamin E deficiency.
Nonsteroidal anti-inflammatory drugs (NSAIDs).
Anthralin, a cream used to treat psoriasis.
Foods high in unsaturated fatty acids, usually plant-based foods.
What are the symptoms of melanosis coli, and how is it diagnosed?
Melanosis coli does not cause symptoms. Most people only learn they have it because it shows up on an unrelated procedure, such as a colonoscopy or flexible sigmoidoscopy. During a colonoscopy, a gastroenterologist looks inside the colon for growths such as polyps or signs of colon cancer, and may notice the darker lining along the way[1].
No special test is needed beyond what the provider sees during the exam. Your provider may use the finding as a chance to talk about your laxative use and long-term ways to manage constipation[1].
How is melanosis coli treated, and is it reversible?
The most effective treatment is to stop taking laxatives that contain anthraquinones. Because the condition is reversible, the colon lining returns to its normal color once the triggering substance is removed. This typically takes six to twelve months[1][2].
To manage constipation without stimulant laxatives, providers often recommend[1]:
Increase fiber: eat more whole grains, fruits, and vegetables to help regulate bowel movements.
Stay hydrated: drink enough fluids to soften stool, and limit drinks that dehydrate, such as those with alcohol or caffeine.
Get active: exercise can stimulate the bowel.
Switch laxatives: if needed, a bulking laxative or stool softener may be a better option. Your provider can advise you.
Stopping the laxatives, adding fiber and fluids, and allowing time for the colon to heal.
Is Melanosis Coli Linked to Cancer?
No. Melanosis coli is not a sign of colon cancer, and it does not mean you are at higher risk of it. Some people worry because long-term use of anthraquinone laxatives has caused tumors in rats, but there is no evidence of a direct link between these laxatives and colon cancer in humans. Researchers continue to study their safety, and overusing any laxative, including stimulant laxatives, can carry health risks[1][3].
What is the bottom line on melanosis coli?
Melanosis coli looks alarming but is a harmless, reversible change rather than a health threat. It is usually a sign to take a different approach to constipation. If you are concerned about your digestive health or how much you rely on laxatives, talk to a healthcare professional, who can help you build a safe long-term plan[1].
Frequently Asked Questions
What exactly is melanosis coli?
Melanosis coli is a harmless, noncancerous condition that makes the inner lining of the colon look dark brown or black.
Is melanosis coli a sign of colon cancer?
No. It is not cancerous and does not increase your risk of colon cancer or other serious conditions.
What causes the dark color in the colon?
A pigment called lipofuscin builds up in the colon wall after the cells lining the colon are damaged by certain laxatives.
Which laxatives cause melanosis coli?
Stimulant laxatives that contain anthraquinones, such as senna, aloe, cascara sagrada, rhubarb, buckthorn, and frangula.
Does melanosis coli cause any symptoms?
No. It does not cause pain or digestive problems.
How is melanosis coli usually discovered?
Melanosis coli is usually found by chance during a colonoscopy or flexible sigmoidoscopy done for another reason.
Is the condition permanent?
No. It is reversible once you stop taking the laxatives that caused it.
How long does it take for the colon to return to normal?
It typically takes six to twelve months after you stop the laxatives.
Can I have melanosis coli without taking laxatives?
Yes, although it is less common. Other possible causes include chronic diarrhea, IBD, IBS, vitamin E deficiency, NSAIDs, and anthralin cream.
Should I be worried if I am diagnosed with melanosis coli?
No. It is benign and does not affect your colon or overall health. It is usually a sign that you may need a different approach to managing constipation.
Related Reading
Laxatives: Types, How They Work, Safe Use and When to Get Help explains laxative types, including the stimulant kinds linked to melanosis coli.
Colonoscopy: Purpose, Prep, Procedure, Results and Risks describes the exam where melanosis coli is usually found.
Constipation: Symptoms, Causes, Diagnosis and Treatment — What You Need to Know covers the causes of constipation and ways to treat it.
Colon Polyps: Complete Guide to Symptoms, Causes, and Treatment explains colon polyps, which can stand out against a darkened colon lining.
References
Cleveland Clinic. Melanosis Coli. Cleveland Clinic. August 27, 2024. https://my.clevelandclinic.org/health/diseases/melanosis-coli
Yang N, Ruan M, Jin S. Melanosis coli: a comprehensive review. Gastroenterol Hepatol. 2020;43(5):266-272. PMID 32094046. https://doi.org/10.1016/j.gastrohep.2020.01.002
Lombardi N, Crescioli G, Maggini V, et al. Anthraquinone laxatives use and colorectal cancer: a systematic review and meta-analysis of observational studies. Phytother Res. 2022;36(3):1093-1102. PMID 35040201. https://doi.org/10.1002/ptr.7373
Wang Y, Li L, Niu X, et al. Melanosis coli: a contrast effect or an oncogenic effect? A large-scale retrospective cohort study. Int J Colorectal Dis. 2023;38(1):63. PMID 36884096. https://doi.org/10.1007/s00384-023-04357-1
Medical disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. The clinical information in this guide reflects source material last reviewed in August 2024.
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