What are the most common signs of an unhealthy gut?

The most common signs are bloating and excess gas, irregular bowel habits (constipation or diarrhea), persistent fatigue, new food intolerances, mood changes such as anxiety or low mood, skin problems, and frequent infections. These reflect the gut's roles in digestion, immunity, and the gut–brain axis.

Can an unhealthy gut cause tiredness?

Yes. Poor gut health can impair nutrient absorption and drive low-grade inflammation, both of which can contribute to fatigue. The gut also influences sleep and mood through the gut–brain axis, which can compound tiredness.

When should I see a doctor about gut symptoms?

See a clinician promptly if you have blood in your stool, unexplained weight loss, persistent pain, a sudden change in bowel habits lasting more than a couple of weeks, or symptoms that interfere with daily life. These warrant professional evaluation rather than self-management.

GUT HEALTH

7 Signs of an Unhealthy Gut (and What They Mean)

By The Scora Science Team · June 26, 2026

TL;DR

Common signs of an unhealthy gut include bloating and gas, irregular bathroom habits, fatigue, food intolerances, unexplained mood changes, skin issues, and frequent illness. One sign alone is rarely cause for concern; a persistent cluster is worth investigating with a clinician.

Your gut does far more than digest food. It trains your immune system, helps regulate your mood through the gut–brain axis, and hosts trillions of microbes that keep the whole system in balance. So when something is off in your gut, the signals often show up in surprising places.

Here are seven of the most common signs — and what the science suggests they mean.

1. Bloating and gas

Occasional gas is normal. But frequent, uncomfortable bloating can signal an imbalance in how your microbes are fermenting food, or how efficiently your gut is moving.

2. Irregular bathroom habits

Constipation, diarrhea, or swinging between the two can reflect changes in gut motility and microbial balance. Consistency and frequency are genuinely useful health signals.

3. Constant fatigue

If you’re sleeping enough but still exhausted, your gut may be involved — through impaired nutrient absorption or low-grade inflammation.

4. New food intolerances

Foods you used to tolerate suddenly causing trouble can point to changes in your gut lining or microbiome.

5. Mood changes

Because most of your serotonin is made in the gut, an imbalanced microbiome can show up as anxiety, low mood, or brain fog. This is the gut–brain axis at work.

6. Skin issues

Inflammation that starts in the gut can surface on the skin — flare-ups of acne, eczema, or redness sometimes track with gut health.

7. Frequent illness

Around 70% of your immune system lives in and around your gut. A struggling gut can mean a weaker defense and slower recovery.

What to do next

One sign on its own is rarely cause for alarm. A persistent cluster is your body asking for attention. The basics help most people: more plant diversity and fiber, fermented foods, better sleep, stress management, and movement. (See our complete guide to gut health.)

And if you have warning signs — blood in stool, unexplained weight loss, persistent pain, or a sudden lasting change in habits — see a clinician. This article is educational, not medical advice.