When we talk about the causes of heartburn, we often focus on diet, smoking, hiatus hernias, and eating large meals. Common culprits like fatty foods, spicy foods, and caffeine are at the forefront of lifestyle changes. But is there a connection between dehydration and heartburn?

Sometimes, it feels like everywhere you go, you’re being told to drink more water. That’s not just a marketing ploy by bottled water companies. Around 50-75% of people are chronically dehydrated. Most people rely on caffeinated beverages, like tea or coffee, or worse, sugary drinks, as their main source of hydration.

The problem? This can exacerbate the signs of heartburn, triggering further dehydration. Coffee, for example, is a diuretic.

So, does dehydration cause heartburn? And what can you do about it?

The Connection Between Dehydration and Heartburn

In short, dehydration can cause heartburn.

Water is essential for life. Almost every single bodily process relies on water, including digestion. When we’re dehydrated, the body begins to slow down like an engine low on oil.

When you’re dehydrated:

• Your body produces less saliva, which normally helps neutralise stomach acid and wash it back down into the stomach.

• The mucus lining of your oesophagus and stomach can become thinner, making tissues more sensitive to acid.

• Low fluid intake can also slow digestion, increasing the chance of reflux as food and acid stay in the stomach longer.

So, dehydration doesn’t directly cause acid reflux. But it can make your existing reflux worse or tip you over the line into a reflux episode. Being well-hydrated can reverse these problems, letting your body repair itself and function at its optimum.

Why Dehydration Causes Heartburn?

Dehydration affects every system in your body. Your digestive system, in particular, relies on water at each stage of the process.

In your mouth, water is present in saliva. Saliva contains bicarbonate, which naturally neutralises stomach acid. The less you salivate, the lower your stomach pH becomes (the more acidic it gets). That also means there’s less protection for your oesophageal lining — so the burning sensation lasts longer.

In your stomach, the protective mucus starts to thin. This mucus is made up of special proteins and water. If there’s less water, it becomes thinner and less effective. That opens the door to acidic irritation, reflux, and heartburn.

Finally, there’s simply a dilution aspect. If you add water, it becomes less acidic. The same is true in your stomach. If your primary source of hydration is coffee or tea, these slightly acidic liquids can exacerbate rather than soothe the situation.

Does Water Help Heartburn?

Yes.

Drinking water during a heartburn episode will provide some relief from symptoms. It often isn’t enough to completely reverse the episode, but it can help.

Over the medium-to-long term, drinking plenty of water will reduce the prevalence of symptoms. It increases your saliva and mucus production, protecting your upper digestive system.

But we should talk about the kind of fluid you’re drinking. Often, if you rely on just water, your kidneys quickly filter it out. Consuming water with a meal or adding a little salt, sugar, and lemon juice can ensure your body holds onto the water – but don’t go overboard!

How Much Water Do You Need?

For most healthy adults, a good general target is about 2 to 2.5 litres of water per day — that’s roughly 8 to 10 glasses.

What people often misunderstand about this target is that most of your water intake comes from food. For example, foods like cucumber, watermelon, and leafy greens are water-rich. Moreover, lots of common dishes contain lots of water mixed with nutrients, helping to increase absorption.

Just drinking water alone — while important — usually isn’t sufficient for optimal hydration.

You might need to drink more water depending on:

• Body size and activity level. Bigger people require more water to stay hydrated as they have more cells. Active people who sweat more also need more water — up to 3 litres per day is not uncommon.

• Environment. If you live in a hot or dry climate, fluid loss increases.

• Diet. High-salt or high-protein diets require more water.

• Health conditions. If you’ve got a fever, diarrhoea, vomiting (or take certain diuretics), your water requirements are higher.

The best indicator of your hydration level is the colour of your urine. Pale yellow or clear indicates good hydration. Darker yellow means you need more fluids. Don’t drink all your water in one go though — it’s best to sip throughout the day.

Get Your Heartburn and Hydration Checked

If you’re struggling with frequent heartburn or indigestion, dehydration could be part of the problem — but it’s rarely the whole story.

The Functional Gut Clinic offers specialist testing to uncover the root cause of your reflux symptoms, from oesophageal pH monitoring to full digestive health assessments.

Find out what’s really driving your heartburn. Book your heartburn and reflux assessment today.