Learn about 20 possible warning signs that can sometimes occur with cancer, including unexplained weight loss, persistent fatigue, unusual bleeding, lumps, skin changes, and ongoing digestive symptoms.
Cancer can sometimes develop quietly, which is why paying attention to new or persistent changes in your body is important. However, there is no single symptom that proves someone has cancer. In fact, many symptoms associated with cancer are much more commonly caused by infections, inflammation, medications, hormonal changes, or other non-cancerous conditions.
The following signs are worth knowing—not because they mean you have cancer, but because persistent or unexplained changes deserve medical attention.
1. Unexplained Weight Loss
Losing weight without changing your diet or exercise routine can sometimes be a warning sign.
The American Cancer Society notes that unexplained weight loss of around 10 pounds (4.5 kg) or more can occur with some cancers.
There are many other possible causes, including thyroid problems, digestive disorders, stress, infections, and medication effects.
2. Persistent or Extreme Fatigue
Everyone gets tired, but cancer-related fatigue can be unusually persistent and may not improve adequately with rest.
Fatigue can also result from anemia, poor sleep, infections, nutritional deficiencies, stress, and many other conditions.
3. A New Lump or Swelling
A new lump anywhere on the body should be evaluated, especially if it persists or changes.
Lumps can occur for many harmless reasons, including infections and cysts, but some cancers can cause masses or enlarged lymph nodes.
4. Unexplained Bleeding
Bleeding that doesn’t have an obvious explanation deserves attention.
Examples include blood in the stool or urine, unusual vaginal bleeding, coughing up blood, or unexplained bruising.
5. Changes in Bowel Habits
A persistent change in bowel habits—such as diarrhea, constipation, or a noticeable change in stool appearance—can have many causes.
If the change continues or is accompanied by blood, abdominal pain, or unexplained weight loss, speak with a healthcare professional.
6. Blood in the Stool
Blood in the stool can result from conditions such as hemorrhoids, anal fissures, infections, or inflammatory bowel disease.
However, it can also occur with colorectal cancer, so unexplained or recurring blood should be medically evaluated.
7. Persistent Cough or Hoarseness
A cough that doesn’t go away or persistent hoarseness can have numerous causes, including allergies, reflux, asthma, infections, and smoking.
Occasionally, these symptoms can be associated with cancers affecting the respiratory system.
8. Difficulty Swallowing
Persistent difficulty swallowing—sometimes described as food feeling stuck—shouldn’t simply be ignored.
It can be caused by reflux, inflammation, neurological problems, or structural issues, but it can also occur with certain cancers.
9. Ongoing Indigestion or Heartburn
Frequent indigestion, heartburn, or abdominal discomfort is usually caused by something other than cancer.
Still, persistent symptoms—particularly when accompanied by difficulty swallowing, vomiting, bleeding, or unexplained weight loss—should be discussed with a doctor.
10. Persistent Abdominal Pain
Pain in the abdomen that is new, unexplained, persistent, or progressively worsening deserves evaluation.
Abdominal pain has an enormous range of possible causes, from digestive problems to infections and gallbladder conditions. Cancer is only one possibility.
11. Loss of Appetite
A noticeable and persistent reduction in appetite can occur with many illnesses.
Cancer can sometimes cause appetite changes, particularly when it affects the digestive system or alters the body’s metabolism.
12. Repeated Nausea or Vomiting
Occasional nausea is common and usually isn’t a sign of cancer.
But persistent nausea or vomiting—especially when combined with abdominal pain, difficulty eating, weight loss, or blood—should be evaluated.
13. A Skin Change That Doesn’t Heal
Pay attention to sores that don’t heal normally, unusual growths, or persistent changes in the skin.
A new mole or an existing mole that changes in size, shape, or color should also be checked.
14. Unusual Changes in a Mole
A changing mole isn’t automatically melanoma, but changes deserve attention.
Look for changes in size, shape, color, or other noticeable differences from how the mole previously appeared.
15. Unexplained Fever
Fever is commonly caused by infection, but unexplained or recurring fever can sometimes accompany cancer.
Persistent fever without an obvious cause should be discussed with a healthcare professional.
16. Night Sweats
Heavy night sweating can occur for many reasons, including infections, hormonal changes, medications, and environmental factors.
However, unexplained night sweats—particularly when combined with fever, fatigue, swollen lymph nodes, or unexplained weight loss—deserve medical evaluation.
17. Changes in Urination
Changes such as blood in the urine, pain during urination, or a persistent change in urinary frequency can have several causes.
Blood in the urine should be evaluated rather than assumed to be harmless.
18. Persistent Swollen Lymph Nodes
Lymph nodes often become enlarged during ordinary infections.
However, a lump or swollen lymph node that persists, grows, or occurs without an obvious infection should be checked by a healthcare professional.
19. Persistent Headaches or Neurological Changes
New or persistent headaches can have many causes and are usually not related to cancer.
But neurological changes such as persistent headaches accompanied by vision changes, seizures, weakness, balance problems, or other unusual symptoms require medical evaluation.
20. Jaundice or Yellowing of the Skin and Eyes
Yellowing of the skin or whites of the eyes is known as jaundice.
It can result from liver or gallbladder problems, infections, certain medications, and other conditions. It can also occur with some cancers, particularly when the liver or bile ducts are affected.
When Should You See a Doctor?
Don’t panic if you recognize one of these symptoms. Having one or even several of these symptoms does not mean you have cancer.
The National Cancer Institute emphasizes that cancer symptoms are often caused by other illnesses or problems. However, symptoms that persist for a couple of weeks, don’t improve, or become worse should be evaluated.
Your doctor may perform an examination and, depending on your symptoms and risk factors, recommend blood tests, imaging, screening, or other diagnostic tests.
Don’t Wait for Pain
An important misconception is that cancer must cause pain.
That’s not always true. Some cancers can produce few or no symptoms early on, which is one reason recommended screening tests are important for eligible people.
Final Takeaway
Your body can produce many signals when something isn’t right—but those signals aren’t a diagnosis.
Unexplained weight loss, persistent fatigue, new lumps, unusual bleeding, ongoing cough, bowel or urinary changes, skin changes, and persistent digestive symptoms are all worth paying attention to when they don’t resolve.
The goal isn’t to fear every unusual symptom. It’s to notice significant changes, avoid ignoring persistent problems, and get appropriate medical advice when needed.
Early evaluation can help identify the real cause—whether it’s cancer or something much more common and treatable.