I'm A Doctor – Here's When To Worry About Blood In Your Stool

<span class="copyright">Antonio Hugo Photo via Getty Images</span>
Antonio Hugo Photo via Getty Images

Noticing streaks of red on your loo roll can be a troubling sight.

And while the NHS says “a small amount of one-off bleeding from the bottom is not usually a serious problem,” bleeding when you pass a stool can sometimes be a sign of more serious health issues.

In a recent TikTok, Dr Karan Rajan was asked: “How do you tell the difference between bleeding from colon cancer versus haemorrhoids?”

Though you should see your GP if you notice any changes you’re worried about, the doctor shared some signs that might suggest where your blood is coming from.

How can I tell haemorrhoid bleeding vs. something more serious?

“Blood from colon cancer is often dark red,” the doctor began.

That’s because it comes from higher up in your digestive system, so may have had a longer time to sit in your bowels ― the older it gets, the darker it becomes.

It may even be “black and tarry” due to this, Dr Rajan explained.

Meanwhile bleeding from something lower down your digestive tract, like haemorrhoids or an anal fissure, tends to be lighter red as it comes from veins near the anus.

Then, there’s the placement of the blood to consider. Blood from colon cancer is more likely to be mixed into the stool than that from a haemorrhoid, “giving the stool a darker or streaked appearance”.

But blood from haemorrhoids “usually appears on the toilet paper after wiping, on the surface of the stool, or even as drops in the toilet bowl, rather than being mixed into the stool ― think of it as a pizza topping rather than being baked into the dough”.

Colon cancer often comes with other symptoms, the doctor added, like diarrhoea, constipation, unintended weight loss, abdominal pain, and fatigue.

Haemorrhoids ― or piles ― typically only cause symptoms around the anus such as itching, rectal pain, and maybe some lumps.

What if I don’t think my bleeding is from colon cancer?

That’s no reason not to get it checked out.

“If you notice persistent rectal bleeding, regardless of the form it takes or the colour, you should get it checked out to rule out the worst-case scenario,” Dr Rajan concluded.

The NHS says you should see your doctor if the issue persists for more than three weeks, regardless of what the blood looks like.

You should also visit your GP if your poo has been softer or thinner than usual, if you have a pain in your abdomen, if you’re unusually tired or if your child noticed blood in their poo.

Call 999 or go to A&E if the bleeding is nonstop or there’s so much blood that “the toilet water turns red or you see large blood clots”.

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