Losing weight without changing your diet or activity can happen for many reasons, including stress, thyroid conditions, digestive problems, medications and infections.
Cancer is another possible cause, so significant or continuing weight loss that you can’t explain deserves medical evaluation.
2. A Persistent or Worsening Cough
Most coughs aren’t caused by cancer. Infections, allergies, asthma, reflux and smoking are among the many more common explanations.
However, a cough that doesn’t go away or continues getting worse should be checked, particularly if it’s accompanied by shortness of breath, chest pain, unexplained weight loss or blood.
3. Persistent, Unusual Fatigue
Everyone gets tired, especially after poor sleep, illness or a stressful week.
What deserves more attention is severe or persistent fatigue that feels unusual for you and doesn’t have an obvious explanation, particularly when other symptoms are present.
4. A New Lump or Swelling
Lumps can result from cysts, infections, swollen lymph nodes and many benign conditions.
Still, a new or persistent lump shouldn’t be diagnosed by touch alone. If you notice unexplained swelling or a lump in areas such as the neck, underarm, abdomen or groin—or anywhere else on your body—have it evaluated.
5. Unusual Bleeding
Unexpected bleeding can include unusual vaginal bleeding or discharge, coughing up blood, or blood appearing in urine or stool.
There are many possible causes, but unexplained bleeding shouldn’t simply be assumed harmless.
6. Persistent Changes in Bowel Habits
Occasional constipation or diarrhea is common. A lasting change from your normal bowel pattern is different.
Persistent diarrhea, constipation, changes in stool, abdominal discomfort or the feeling that your bowel hasn’t emptied completely can have numerous causes, including colorectal conditions that require medical attention.
7. Blood in or on the Stool
Hemorrhoids and other gastrointestinal conditions can cause rectal bleeding, so seeing blood doesn’t automatically mean cancer.
But blood in or on the stool should still be discussed with a healthcare professional, especially when it recurs or accompanies other bowel changes.
8. Blood in the Urine
Urinary infections, kidney stones and other conditions can cause blood in the urine. It can also occur with bladder and other urinary-tract cancers.
The important point isn’t to guess which explanation applies. It’s to find out why the bleeding occurred.
9. Persistent Indigestion or Difficulty Swallowing
Occasional heartburn after a heavy meal is common. Persistent indigestion, repeated pain after eating or increasing difficulty swallowing deserves more attention.
If swallowing becomes difficult or digestive symptoms repeatedly return without a clear explanation, mention them to your doctor.
10. Persistent Abdominal Pain or Bloating
Temporary bloating is extremely common and usually isn’t a reason for alarm.
Persistent or worsening abdominal pain, swelling, pressure or unexplained bloating is different. Digestive, gynecological, urinary and numerous other conditions can cause these symptoms, so ongoing changes are better evaluated than self-diagnosed.
11. Unexplained Appetite Changes
Stress, illness and medications can temporarily affect appetite.
A sustained change without an obvious explanation—particularly when accompanied by weight loss, fatigue, nausea or other digestive symptoms—is worth discussing with a healthcare professional.
12. A Sore That Doesn’t Heal
Most minor wounds heal normally.
A sore that remains for an unusually long time, repeatedly crusts or bleeds, or continues changing should be examined. This is particularly important for persistent abnormalities on sun-exposed skin.
13. A New or Changing Mole
Moles naturally vary, and most aren’t cancerous.
Pay attention to a spot that’s new, changing or noticeably different from your other moles. Rather than trying to diagnose it by comparing it with internet photographs, have a concerning lesion professionally evaluated.
14. Other Persistent Skin Changes
Not every concerning skin change is a mole.
A growth that repeatedly bleeds, a persistent scaly area, a non-healing lesion or another unusual change may deserve evaluation. Yellowing of the skin or whites of the eyes also warrants medical attention because it can indicate several underlying conditions.
15. Persistent Hoarseness
A cold, heavy voice use or throat irritation can temporarily make your voice raspy.
Hoarseness or another unexplained voice change that doesn’t resolve should be checked rather than repeatedly dismissed.
16. Unexplained Fever or Night Sweats
Infections are a common cause of fever, and night sweats have many possible explanations.
But recurrent fever or significant night sweats without a known cause can sometimes signal an underlying medical condition that requires investigation.
17. Persistent Shortness of Breath
Being winded after strenuous exercise is one thing. Developing unexplained breathlessness during ordinary activity or experiencing shortness of breath that persists is another.
Sudden or severe difficulty breathing requires urgent medical attention rather than waiting to see whether it disappears.
18. New or Persistent Chest Pain
Chest pain can come from muscles, reflux, heart conditions, lung problems and numerous other causes.
Because some causes are medical emergencies, new or unexplained chest pain shouldn’t automatically be attributed to something minor. Severe or sudden chest pain—particularly with difficulty breathing, fainting, sweating or other concerning symptoms—requires urgent assessment.
19. Changes in the Breast
Changes worth noticing include a new lump or firm area, nipple changes or unusual discharge, dimpling or puckering of the skin, persistent redness or scaling, or another new change in the breast.
Many breast changes are benign, but a new or unexplained abnormality should be properly evaluated.
20. Unexplained Neurological Changes
New headaches, seizures, changes in vision or hearing, facial weakness and other neurological symptoms can have many different causes.
Some require immediate attention for reasons unrelated to cancer. Sudden facial drooping, weakness or numbness, difficulty speaking or sudden vision changes can be signs of a stroke and require emergency care.
Having One of These Symptoms Does Not Mean You Have Cancer
This is the most important point.
These symptoms occur in many conditions, and most are not specific to cancer. A cough might come from an infection. Fatigue might result from poor sleep. A lump might be a benign cyst. Blood in the urine could be caused by an infection or kidney stone.
That’s precisely why symptom lists shouldn’t be used to diagnose yourself.
Their purpose is to help you recognize when a change may deserve professional evaluation.
When Should You See a Doctor?
There isn’t one waiting period that applies to every symptom.
As a general principle, contact a healthcare professional when something is new, unexplained, persistent, worsening or significantly different from what’s normal for you. The original guidance notes that symptoms persisting for a couple of weeks are a reason to seek medical advice rather than continuing to wait indefinitely.
Some symptoms shouldn’t wait at all. Severe difficulty breathing, severe or sudden chest pain, significant coughing of blood, fainting or sudden neurological symptoms may require urgent or emergency care.
Screening and Symptoms Aren’t the Same Thing
Cancer screening is performed in people who may have no symptoms, with the goal of finding certain cancers or precancerous changes earlier.
A diagnostic evaluation is different: it investigates a symptom, physical finding or abnormal test result.
That means a person shouldn’t wait until symptoms appear before learning which routine screenings are appropriate for their age and risk factors. Likewise, a previous normal screening test isn’t a reason to ignore a new concerning symptom.
Keep Track of Persistent Changes
If something doesn’t seem urgent but continues happening, a simple symptom record can help.
Note when the problem started, how often it occurs, whether it’s becoming better or worse, what seems to trigger it and whether you’ve noticed other changes in weight, appetite, sleep or energy.
Specific information such as “I’ve had this four or five times a week for three weeks” is generally more useful during an appointment than simply saying you’ve felt unusual lately.
Don’t Wait for Something to Hurt
Serious illness doesn’t always cause pain early.
A painless lump, changing skin lesion, unusual bleeding or persistent voice change can still deserve medical attention.
The absence of pain doesn’t necessarily mean a symptom is harmless.
Awareness Without Fear
The goal isn’t to monitor every sensation or assume the worst whenever something changes.
It’s much simpler:
Pay attention to what’s normal for you. Notice meaningful changes. Keep up with appropriate health screenings. And when something remains unexplained or isn’t going away, ask a healthcare professional about it.
Most symptoms on lists like this will turn out to have explanations other than cancer.
But reassurance should come from understanding the cause—not from ignoring a persistent change.
A symptom is a signal, not a diagnosis.
Listening to that signal doesn’t mean panicking.
It means taking your health seriously.
Medical note: This article is for general educational purposes and isn’t a substitute for individualized medical advice. New, persistent, worsening or concerning symptoms should be discussed with a qualified healthcare professional. Sudden or severe symptoms may require urgent or emergency medical care.