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Disponible en español: Síntomas del cáncer: a qué prestar atención

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Beginner 6 min readSource checked

Symptoms of Cancer: What to Watch For

A plain-language overview of common symptoms that cancer may cause and when to see a doctor, based on National Cancer Institute resources.

NCI source

NCI last reviewed source: 2019-05-16

An older woman in headscarf holds her throat, looking at the camera
An older woman in headscarf holds her throat, looking at the camera

Key fact

Cancer can cause many symptoms, but these are most often caused by illness, injury, benign tumors, or other problems.

The short answer

Cancer can cause many symptoms, but these symptoms are most often caused by other problems, such as illness, injury, or benign tumors. If you have symptoms that do not get better after a few weeks, see a doctor so problems can be found and treated early. Cancer often does not cause pain.

  • Cancer can cause many symptoms, but these are most often caused by illness, injury, benign tumors, or other problems.

  • If symptoms do not get better after a few weeks, see a doctor so problems can be diagnosed and treated early.

  • Cancer often does not cause pain, so do not wait to feel pain before seeing a doctor.

  • Symptoms can affect many parts of the body, including the breast, bladder, bowel, skin, and mouth.

Choose how you want to understand this

The full explanation.

The simple version

Cancer can cause many symptoms. But these symptoms are most often caused by something else — illness, injury, a benign tumor, or another problem.

See your doctor if a symptom does not get better after a few weeks. Early care means problems get diagnosed and treated as early as possible. Cancer often does not cause pain. Do not wait to feel pain before seeing a doctor.

Most symptoms are not cancer. But a symptom that sticks around for a few weeks is worth checking with a doctor.

When to get help sooner

The usual advice — see someone after a couple of weeks — is for symptoms that stay stable and mild.

  • Call 911 or go to an emergency department now if you have sudden face drooping, one-sided weakness, slurred speech, confusion, or sudden vision or balance loss.
  • Call 911 or go to an emergency department now if breathing is severely difficult, or chest pressure spreads to your arm, back, neck, or jaw.
  • Call 911 or go to an emergency department now if bleeding will not stop, you cough up more than a few teaspoons of blood, or the toilet water turns red.
  • Call 911 or go to an emergency department now if a seizure lasts more than 5 minutes or is your first-ever seizure.
  • Call your care team now, whatever the time, if you are on chemotherapy and your temperature reaches 100.4°F (38°C) or higher, even once. The CDC calls that a medical emergency (CDC). If you cannot reach them right away, go to an emergency department and tell them you are on chemotherapy.
  • Call your care team the same day if you see blood where it does not belong, yellowing skin or eyes, or new back pain with leg weakness.

Everything else can follow the ordinary route: see your doctor within a couple of weeks.

Don't wait for pain

Cancer often does not cause pain. It can be tempting to wait until something hurts before seeing a doctor. That is a mistake. If a symptom lasts a couple of weeks, see a doctor rather than waiting for pain.

Seeing a doctor early gives any problem — cancer or something else — the best chance of being found and treated early.

Symptoms cancer may cause

The symptoms below are ones cancer may cause. Remember: these are most often caused by conditions other than cancer.

Breast changes:

  • A lump or firm feeling in your breast or under your arm.
  • Nipple changes or discharge.
  • Skin that is itchy, red, scaly, dimpled, or puckered.

Bladder changes:

  • Trouble urinating.
  • Pain when urinating.
  • Blood in the urine.

Bleeding or bruising for no known reason.

Bowel changes:

  • Blood in the stools.
  • Changes in bowel habits.

Cough or hoarseness that does not go away.

Eating problems:

  • Pain after eating, such as heartburn or indigestion that doesn't go away.
  • Trouble swallowing.
  • Belly pain.
  • Nausea and vomiting.
  • Appetite changes.

Fatigue that is severe and lasts.

Fever or night sweats for no known reason.

Mouth changes:

  • A white or red patch on the tongue or in your mouth.
  • Bleeding, pain, or numbness in the lip or mouth.

Neurological problems:

  • Headaches.
  • Seizures.
  • Vision changes.
  • Hearing changes.
  • Drooping of the face.

Skin changes:

  • A flesh-colored lump that bleeds or turns scaly.
  • A new mole, or a change in an existing mole.
  • A sore that does not heal.
  • Jaundice, which is yellowing of the skin and whites of the eyes.

Swelling or lumps anywhere, such as in the neck, underarm, stomach, or groin.

Weight gain or weight loss for no known reason.

Specific symptom questions

Some people come to this page with one exact question rather than a whole symptom list. These guides go deeper on patterns like shortness of breath, breast pain, nipple discharge, bloating, jaundice, and loss of appetite.

Newer guides cover more specific searches, including persistent cough, coughing up blood, trouble swallowing, postmenopausal bleeding, bleeding after sex, breast lump, testicular lump, changing mole, night sweats, bone pain, neck lump, a sore that won't heal, seizures, vision changes, unexplained bruising, frequent urination, feeling full quickly, and white patches in the mouth.

Learning about a specific cancer

The list above covers general symptoms. Each type of cancer can have its own symptoms. The National Cancer Institute provides PDQ cancer treatment summaries for adult and childhood cancers. Each summary includes detailed information about symptoms caused by that specific type of cancer.

The best next step for any symptom that lasts is to see a doctor. Early answers help, whatever the cause turns out to be.

Words to know

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An illustration: dNA helix transforming into a cluster of cancer cells

Common questions

What are common symptoms of cancer?

Cancer may cause many symptoms. Some examples include breast changes such as a lump, bladder changes such as trouble or pain when urinating, unexplained bleeding or bruising, bowel changes, a lasting cough or hoarseness, eating problems, severe and lasting fatigue, fever or night sweats for no known reason, mouth changes, neurological problems, skin changes, swelling or lumps, and unexplained weight gain or loss.

Do these symptoms mean I have cancer?

Not usually. Cancer can cause many symptoms, but these symptoms are most often caused by illness, injury, benign tumors, or other problems. Still, if you have symptoms that do not get better after a few weeks, it is important to see a doctor so problems can be diagnosed and treated as early as possible.

When should I see a doctor about symptoms?

See your doctor if you have symptoms that do not get better after a few weeks. Cancer often does not cause pain, so do not wait to feel pain before seeing a doctor. Seeing a doctor early helps problems get diagnosed and treated as early as possible.

Does cancer always cause pain?

No. Often, cancer does not cause pain. That is why the National Cancer Institute advises not to wait to feel pain before seeing a doctor. If you have symptoms that last for a couple of weeks, it is important to see a doctor.

What skin changes can be a symptom of cancer?

Skin changes that cancer may cause include a flesh-colored lump that bleeds or turns scaly, a new mole or a change in an existing mole, a sore that does not heal, and jaundice (yellowing of the skin and whites of the eyes). A doctor can evaluate any of these changes.

Where can I find symptoms for a specific type of cancer?

To learn about symptoms for a specific cancer, the National Cancer Institute provides PDQ cancer treatment summaries for adult and childhood cancers. Each summary includes detailed information about symptoms caused by that specific type of cancer.

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Knowledge Check

0 of 4 answered

  1. Q1.According to this article, what most often causes the symptoms that cancer can cause?
  2. Q2.According to this article, why should a person not wait to feel pain before seeing a doctor?
  3. Q3.According to this article, when should you see a doctor about symptoms?
  4. Q4.According to this article, which of the following is listed as a skin change that cancer may cause?

This self-assessment checks understanding of educational content only. It is not medical advice.

Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.

Sources last checked: 2026-08-13 what this meansLast updated: 2026-08-18Next planned review: 2027-08-03

How this page was created

Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.

Editorial status — Source checked. This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.

General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team for your situation.

Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.

Our editorial processHow we use AIReport an error

How this page was created

Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.

Editorial status: Source checked This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.

Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.

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Symptoms of Cancer: What to Watch For

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