Hemorrhoids can absolutely cause a positive fecal immunochemical test (FIT), and research confirms they are one of the more common reasons for a false-positive result. In one large study, people with hemorrhoids were roughly two and a half times more likely to get a false-positive FIT than those without them. But the relationship is not as straightforward as “hemorrhoids equal unreliable test,” and whether your hemorrhoids actually interfere depends largely on whether they are actively bleeding at the time you collect your sample.
What the FIT Is Actually Detecting
A FIT test works by detecting human hemoglobin in a stool sample. Unlike the older guaiac-based stool tests, which could react to blood from food sources like red meat, FIT uses antibodies that are specific to human blood. This makes it more accurate overall but also means it will pick up blood from any source inside your gastrointestinal tract, not just blood shed by a polyp or tumor. If your hemorrhoids are bleeding enough to leave hemoglobin in the stool, the test has no way to distinguish that blood from blood that might be coming from something more concerning further up in the colon.
The Research Linking Hemorrhoids to False Positives
A study published in the Yonsei Medical Journal examined over 3,500 people who had positive FIT results and then underwent colonoscopy. Among participants found to have hemorrhoids, about 25% had false-positive results, compared with roughly 10% of those without hemorrhoids. Even when researchers isolated people whose only abnormality was hemorrhoids and nothing else, the false-positive rate was still about 15%, compared with just over 3% in people who had no findings at all on colonoscopy.1PubMed Central. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results? – Section: RESULTS After adjusting for other factors like age and sex, hemorrhoids remained an independent predictor of false-positive FIT results, with the odds roughly tripled compared to people without them.2PubMed Central. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results? – Section: Discussion
A more recent study looking broadly at factors behind false-positive FIT results found a similar pattern. Alongside older age, smoking, alcohol use, and higher body mass index, the presence of hemorrhoids was significantly associated with increased odds of a false positive.3PubMed Central. Factors associated with false fecal immunochemical test results in colorectal cancer screening – Section: RESULTS So the connection is well established across multiple research groups.
When Hemorrhoids Don’t Seem to Matter
Here is where it gets interesting and why the answer isn’t simply “hemorrhoids ruin the test.” A large clinical study published in Mayo Clinic Proceedings compared FIT performance in people with and without hemorrhoids and found no statistically significant difference in either sensitivity or specificity. The test correctly identified cancer at about the same rate regardless of hemorrhoid status, and the false-positive rate was nearly identical: around 95% specificity in both groups.4Mayo Clinic Proceedings: Innovations, Quality & Outcomes. Influence of Hemorrhoids on Fecal Immunochemical Test and Multitarget Stool DNA Test Performance – Section: Results
The critical detail is that the hemorrhoids in this study were described as asymptomatic, meaning they were present but not actively causing problems like bleeding. The researchers concluded that in the absence of overt gastrointestinal bleeding, FIT remains a viable screening option regardless of whether someone has hemorrhoids.5PubMed Central. Stool-Based Colorectal Cancer Screening Test Performance Characteristics in Those With and Without Hemorrhoids
So the two sets of findings aren’t really contradictory. Hemorrhoids that bleed can introduce hemoglobin into the stool and trigger a positive FIT. Hemorrhoids that are sitting there quietly, not bleeding, don’t generate enough free blood to move the needle. The test is not reacting to the hemorrhoid itself; it is reacting to the blood the hemorrhoid produces.
Why Bleeding Matters More Than the Hemorrhoid Itself
Hemorrhoids bleed intermittently. You might notice bright red blood on toilet paper one week and nothing the next. This on-again, off-again pattern means that the same person with the same hemorrhoids could test positive on one FIT and negative on another, depending entirely on whether the hemorrhoids happened to be bleeding around the time the stool sample was collected. The FIT is essentially a snapshot of what was happening in your gut during a very narrow window.
This intermittency has practical implications. If you know you have hemorrhoids and they are currently flaring up with visible bleeding, your FIT is more likely to come back positive for reasons unrelated to cancer. That doesn’t mean the result is meaningless, but it does mean the test may be picking up hemorrhoidal blood rather than blood from a polyp or tumor. Conversely, if your hemorrhoids have been calm for weeks, the FIT is less likely to be confounded by them.
Some clinicians suggest collecting the stool sample during a period when hemorrhoids are not actively symptomatic, though formal guidelines on this vary. The practical challenge is that many people have hemorrhoids without knowing it, since internal hemorrhoids often bleed without causing pain or other noticeable symptoms. You can’t always time around something you don’t realize is happening.
Other Reasons a FIT Can Come Back Positive Without Cancer
Hemorrhoids are far from the only non-cancer cause of a positive FIT. Because the test picks up any human blood in the stool, anything that causes bleeding in the gastrointestinal tract can set it off.
- Diverticula: Small pouches in the colon wall that can bleed, and they were identified alongside hemorrhoids as a significant contributor to false-positive FIT results.3PubMed Central. Factors associated with false fecal immunochemical test results in colorectal cancer screening – Section: RESULTS
- Non-cancerous polyps: Benign polyps can bleed, and while finding them is actually useful because some have the potential to become cancer later, they are not cancer at the time of the test.
- Inflammatory conditions: Conditions like ulcerative colitis or Crohn’s disease cause chronic inflammation and bleeding in the gut, which will show up on a FIT.
- Anal fissures: Small tears in the lining of the anus bleed in a way that is very similar to hemorrhoidal bleeding and can easily contaminate a stool sample.
- Upper GI bleeding: Although FIT is most sensitive to blood from the lower gastrointestinal tract, significant bleeding from the stomach or upper intestines can sometimes produce a positive result.
Lifestyle and demographic factors also play a role. The same research that linked hemorrhoids to false positives found that older age, smoking (current or former), alcohol consumption, and higher BMI all independently increased the odds of a false-positive FIT.3PubMed Central. Factors associated with false fecal immunochemical test results in colorectal cancer screening – Section: RESULTS Interestingly, regular exercise and male sex were associated with lower odds of a false positive in that analysis. Some of these factors likely operate through their effects on gut health and bleeding risk rather than through any direct interaction with the test chemistry.
Why You Should Still Follow Up on a Positive Result
Knowing that hemorrhoids can trigger a false positive might tempt you to dismiss a positive FIT, especially if you already know you have hemorrhoids. This is genuinely dangerous reasoning. The whole point of the FIT screening program is to catch colorectal cancer and precancerous polyps early, when treatment is most effective. A positive FIT, regardless of the suspected cause, is a prompt to undergo colonoscopy so a doctor can look directly at the colon and rule out or confirm anything serious.
Hemorrhoids and colorectal cancer can coexist. Having hemorrhoids does not protect you from also having a polyp or tumor. In the Yonsei Medical Journal study, many participants had hemorrhoids alongside other clinically significant findings on colonoscopy.1PubMed Central. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results? – Section: RESULTS If those individuals had attributed their positive FIT entirely to hemorrhoids and skipped the follow-up, the other findings would have gone undetected.
Doctors are well aware that hemorrhoids confound FIT results. A colonoscopy after a positive FIT is not the doctor failing to consider hemorrhoids as a possibility. It is standard practice precisely because the FIT cannot distinguish between sources of bleeding, so a visual inspection of the entire colon is the only way to be confident about what is going on.
The Emotional Side of a False Positive
Getting a letter saying your cancer screening test came back positive is stressful, even if you suspect hemorrhoids are behind it. Research into the psychological consequences of false-positive colorectal cancer screening found that people experienced significant anxiety, discomfort, and changes in how they perceived their own health. Some participants reported ongoing worry even after colonoscopy cleared them, and the experience led some to use more healthcare services afterward as they sought reassurance.6PubMed Central. Psychosocial consequences of receiving false-positive colorectal cancer screening results: a qualitative study – Section: Abstract
For people who go through this cycle repeatedly because their hemorrhoids trigger a positive FIT every screening round, the toll can compound. Some start questioning whether they want to participate in screening at all, which defeats the purpose of the program. If you find yourself in this pattern, it is worth having a frank conversation with your doctor about whether a different screening approach, like scheduling a colonoscopy directly at the recommended intervals rather than using FIT as a gateway, might make more sense for you.
Should People with Hemorrhoids Use a Different Screening Method
This is a question that doesn’t have a single consensus answer, and it depends partly on how symptomatic the hemorrhoids are. For people with quiet, non-bleeding hemorrhoids, the evidence suggests FIT works just as well as it does for anyone else, with no meaningful difference in accuracy.4Mayo Clinic Proceedings: Innovations, Quality & Outcomes. Influence of Hemorrhoids on Fecal Immunochemical Test and Multitarget Stool DNA Test Performance – Section: Results There’s no particular reason for those individuals to avoid FIT or switch to colonoscopy.
For people with frequently bleeding hemorrhoids, the calculus shifts. If hemorrhoidal bleeding causes repeated false-positive FIT results, each one triggers a colonoscopy, which carries its own small risks (perforation, sedation reactions) and costs. After the first or second time a colonoscopy comes back clean except for hemorrhoids, your doctor may recommend moving to direct colonoscopy every ten years as the primary screening strategy instead. Multitarget stool DNA tests are another option, and the Mayo Clinic Proceedings study found that these tests also showed no significant difference in performance based on hemorrhoid status.5PubMed Central. Stool-Based Colorectal Cancer Screening Test Performance Characteristics in Those With and Without Hemorrhoids However, those tests analyze DNA markers in addition to blood, so they operate partly independently of the hemorrhoid issue.
Cutoff Thresholds and Why They Vary
FIT tests are not simply positive or negative in a binary sense at the laboratory level. They measure the concentration of hemoglobin in the stool sample, and the threshold for calling a result “positive” is set by the lab or the screening program. Different countries, and sometimes different labs within the same country, use different cutoff values. A lower cutoff catches more cancers and precancerous polyps but also flags more false positives, including more cases caused by hemorrhoidal bleeding. A higher cutoff misses a few more real cancers but produces fewer false alarms.
Research has examined how hemorrhoids affect FIT results at different cutoff levels.7Gastrointestinal Endoscopy. Hemorrhoids detected at colonoscopy: An infrequent cause of false-positive fecal immunochemical test results – Section: Results Generally, as the cutoff goes up, the influence of hemorrhoids on false-positive rates diminishes because the amount of blood hemorrhoids typically contribute is relatively small. A tumor or large polyp tends to bleed more consistently and at higher volumes than a hemorrhoid. But raising the cutoff is a population-level decision with tradeoffs that go well beyond the hemorrhoid question, so it isn’t something you as an individual can request.
What this means in practice is that some screening programs may have a higher false-positive rate from hemorrhoids than others simply due to the threshold they’ve chosen. If you participate in a program with a lower cutoff value, the test is more sensitive overall but also more likely to be set off by hemorrhoidal blood.
Treating the Hemorrhoids Themselves
If hemorrhoids are causing repeated false-positive FIT results and unnecessary colonoscopies, addressing the hemorrhoids directly can be a practical solution. Mild hemorrhoids often improve with dietary changes (more fiber, more water), topical treatments, and avoiding straining during bowel movements. More persistent hemorrhoids can be treated with procedures like rubber band ligation, sclerotherapy, or in severe cases, surgical removal. Resolving the bleeding source doesn’t just improve your quality of life; it also removes the main confounder from future FIT screening.
That said, treating hemorrhoids purely to improve FIT accuracy is a decision to weigh against the severity of the hemorrhoids themselves. If your hemorrhoids are mild and only occasionally symptomatic, it might make more sense to switch screening strategies rather than pursue a procedure you wouldn’t otherwise need. Your doctor can help sort through this, ideally before the next screening round rather than after another positive result.
Medications That Can Contribute to Bleeding
Blood-thinning medications, including aspirin, warfarin, and newer anticoagulants, can increase bleeding from hemorrhoids and from other GI sources. If you take one of these medications and also have hemorrhoids, both factors can independently increase the chance of a positive FIT. Some screening guidelines suggest that you do not need to stop blood thinners before taking a FIT, since the test is meant to be done as part of your normal daily routine. But it is worth being aware that the combination of hemorrhoids and blood thinners is especially likely to produce a positive result.
Nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen can also contribute by causing small amounts of GI bleeding, particularly in the stomach and upper intestine. Long-term or high-dose use of these medications is another risk factor for a positive FIT that has nothing to do with cancer. If you have hemorrhoids and regularly take NSAIDs, you’ve got two separate reasons why a FIT might come back positive unrelated to a tumor.
The Bigger Risk of Dismissing a Positive FIT
One theme worth returning to for emphasis: the real danger with hemorrhoids and FIT isn’t the false positive itself. It’s the temptation to wave off the result. Studies on colorectal cancer screening consistently show that incomplete follow-up after a positive FIT is one of the biggest gaps in the screening chain. People who receive a positive result but never get a colonoscopy lose the entire benefit of having been screened in the first place. Hemorrhoids give people a plausible-sounding reason to skip follow-up, and that reasoning, while understandable, can have serious consequences. Colorectal cancer caught early has a very different prognosis than colorectal cancer caught late, and the colonoscopy triggered by a positive FIT is a crucial step that often catches polyps before they ever become cancer at all.