A stomach ulcer doesn’t always begin with unbearable pain. In some people, the first symptoms can be mild, intermittent, or easily mistaken for indigestion.

A peptic ulcer is an open sore that develops in the lining of the stomach or the first part of the small intestine. Two common causes are Helicobacter pylori (H. pylori) infection and frequent use of certain pain relievers known as NSAIDs, such as ibuprofen and naproxen.

Here are seven symptoms worth knowing.

1. Burning or gnawing pain in the upper abdomen

This is one of the classic symptoms.

The discomfort is usually felt between the breastbone and belly button and may feel like burning, aching or gnawing.

For some people, the pain becomes more noticeable when the stomach is empty or during the night. Eating may temporarily improve symptoms in some cases, while making them worse in others.

2. Feeling unusually full after eating

You may notice that you become full much sooner than you used to.

This can be easy to dismiss, particularly if there isn’t severe pain accompanying it. Persistent early fullness, however, is something worth discussing with a healthcare professional.

3. Frequent bloating

Occasional bloating is extremely common and usually isn’t a sign of an ulcer.

But when persistent bloating occurs together with upper abdominal discomfort, nausea or other digestive symptoms, it’s worth paying closer attention.

4. Nausea

An ulcer can sometimes cause nausea or an unsettled feeling in the stomach.

Some people experience it in the morning or when they haven’t eaten for several hours.

Vomiting can also occur, although persistent vomiting requires medical evaluation.

5. Frequent belching or indigestion

Repeated belching, indigestion and upper abdominal discomfort can accompany an ulcer.

The problem is that these symptoms are also associated with many other digestive conditions, including acid reflux. Symptoms alone can’t confirm that an ulcer is present.

6. Loss of appetite or unexplained weight loss

If eating repeatedly causes discomfort, some people begin eating less without consciously intending to.

Over time, this can contribute to unintentional weight loss.

Unexplained weight loss should always be taken seriously because many conditions—not only ulcers—can cause it.

7. Dark stools or vomiting blood

This is different from the other symptoms on this list because it can indicate a bleeding ulcer and requires urgent medical attention.

Bleeding higher in the digestive tract can cause stool to become black, sticky or tar-like.

Vomited blood may appear bright red or sometimes resemble coffee grounds.

If this happens, seek urgent medical care rather than waiting to see whether the problem disappears.

What actually causes stomach ulcers?

There’s a persistent myth that ulcers are primarily caused by stress or spicy foods.

Those things may aggravate symptoms in some people, but they aren’t the main causes of most peptic ulcers.

Two major causes are H. pylori infection and regular use of NSAID pain relievers.

Smoking can also interfere with healing and increase the risk of complications.

How are ulcers diagnosed?

A doctor may recommend testing for H. pylori, which can involve a breath test, stool test or other testing.

Depending on the symptoms, age and risk factors, an upper endoscopy may sometimes be recommended. This allows a doctor to directly examine the stomach and upper digestive tract.

Treatment depends on the cause. H. pylori infections are generally treated with a combination of medications, while ulcers associated with NSAIDs may require changes to those medications and treatment to reduce stomach acid.

When should you get medical help?

Persistent or recurring stomach pain deserves medical evaluation, especially when accompanied by vomiting, loss of appetite or unexplained weight loss.

Seek urgent medical attention for vomiting blood, black tarry stools, fainting or dizziness associated with possible bleeding, or sudden severe abdominal pain.

The bottom line

Stomach ulcers don’t always announce themselves with extreme pain.

Sometimes the first clues are relatively ordinary digestive complaints—burning discomfort, nausea, early fullness or recurring indigestion.

These symptoms don’t automatically mean you have an ulcer, but persistent or worsening symptoms shouldn’t simply be ignored.

Recognizing the warning signs is useful. Getting the correct diagnosis is what really matters.