It starts as a warm ache behind the breastbone, somewhere between dessert and bedtime. By the time you lie down it's climbing, a sour taste reaches the back of your throat, and you're propping yourself up on pillows, chewing an antacid and wondering why a nice dinner has turned into this again.
Heartburn comes with a simple story attached: too much acid, so knock it down. The tablets work for the night, and the burning comes back. One reason is hiding in the pills themselves. Another sits in the timing of an ordinary evening. And for some stomachs, the simple story runs exactly backwards.
What's happening when it burns
At the bottom of the food pipe sits a ring of muscle that works like a one-way valve. It opens to let food into the stomach and closes to keep the stomach's contents where they belong. Stomach acid is strong enough to dissolve metal, and the stomach survives it only because its lining is coated in thick mucus and replaces itself every few days. The food pipe has no such shield, which is why a few seconds of splash-back hurts.
Reflux happens when that valve relaxes at the wrong moment, or when pressure from below pushes stomach contents back up through it. A little reflux after a big meal is normal. When it happens often enough to cause symptoms, usually more than once a week, it's called reflux disease, and it affects roughly one adult in five in Western countries.
Sometimes the valve has help going wrong. In a hiatus hernia, part of the top of the stomach slides up through the gap in the diaphragm where the food pipe passes, and the valve loses the support that normally keeps it tight. It's common, more so with age and extra weight, and it's one reason reflux can hang on despite good habits.
Reflux without the burn
Reflux can arrive without any heartburn at all. Sometimes a fine mist of acid reaches the throat and voice box, and the signs look like something else entirely: a hoarse or tired voice, constant throat clearing, a cough that lingers for weeks, a feeling of a lump in the throat, or a sour taste on waking. Because there's no burning in the chest, it gets treated as a cold, an allergy or a dry throat for months. If those signs are worse in the mornings or after big evening meals, think of reflux.
Pressure from below
Much of what helps reflux comes down to three things: less pressure beneath the valve, fewer things that loosen it, and the right amount of acid in the stomach. Pressure is the easiest place to start. A full stomach pushes upwards, and so does anything that squeezes the belly from the outside. That's why reflux is so much worse after a large meal, in tight waistbands, when bending over, and in late pregnancy.
Weight around the middle works the same way, all day. When people in a large Norwegian population were followed for years, those who lost weight saw their reflux ease, and the more weight they lost, the more it eased, including among people who'd needed medicine for it. For anyone carrying extra weight around the waist, losing some of it is one of the most reliable fixes available.
Smaller meals do the same job without waiting for the scales. Four modest meals put far less pressure on the valve than two enormous ones.
Pregnancy brings both problems at once. Hormones relax the valve, and the growing baby presses up on the stomach, so heartburn in the later months is common. Smaller, more frequent meals, an early dinner and sleeping on the left side are the usual first steps; check any remedy with whoever looks after your pregnancy first.
When you eat matters as much as what
The timing of the last meal is one of the most overlooked causes of night-time reflux. People who ate dinner less than three hours before going to bed were several times more likely to have reflux disease than people who left four hours or more. Lying down on a full stomach lets gravity work against you, and the acid has an easy path upward.
Sleeping position helps too. Lying on your left side keeps the stomach below the food pipe, and people who were trained to sleep on their left had less acid in the food pipe overnight. Raising the head of the bed on blocks, so the whole body slopes, helps more than stacking pillows, which bends you at the middle and can squeeze the stomach. Sturdy lift just the head end of the bed and give that steady, even slope.
The first hour after eating counts. A gentle walk helps the stomach empty and keeps you upright, while hard exercise, heavy lifting or bending to the floor straight after a big meal pushes its contents up towards the valve.
Chewing after a meal does a quieter job: it makes you produce more saliva, which washes acid back down the food pipe. Skip mint, since peppermint can relax the valve, and skip gums sweetened with xylitol, which has been linked to stickier blood and a higher risk of heart attack and stroke. Mastic, a natural resin from a tree on the Greek island of Chios, has been chewed for thousands of years with nothing added, and in people with indigestion, three weeks of mastic eased stomach pain and heartburn. comes as the raw "tears".
The foods and habits that set it off
Some foods relax the valve or add to the acid: large meals, alcohol, chocolate, peppermint, coffee and other caffeinated drinks, fizzy drinks, and for some people citrus, tomato, onion and spicy food. The list is personal, and a food that sets one person off can leave another untouched. A week or two of notes on what you ate and when the burning started usually shows your own pattern faster than any list.
Smoking belongs on the list. Nicotine relaxes the valve, and when people in the same Norwegian group gave up smoking, their reflux improved, most clearly among those at a healthy weight.
Some everyday medicines play a part. Certain blood-pressure tablets, anti-inflammatory painkillers, some asthma and sleeping tablets, and HRT can relax the valve or irritate the food pipe. If your reflux started around the time you began something new, raise it the next time your medicines are reviewed.
The low-carb surprise
One finding about reflux points somewhere unexpected: the bread basket. When adults with reflux switched to a diet with almost no carbohydrate, the amount of acid reaching their food pipe fell and their symptoms improved within days. The groups were small, and the pattern matches what people eating keto or carnivore report: heartburn that had followed them for years fading within the first week or two.
The likely reasons are that fewer starchy, sugary foods mean less fermentation and gas in the gut, so less pressure pushing upwards, and that the weight lost on low-carb eating takes more pressure off the valve. Meals built on meat, fish and eggs also tend to be smaller and more filling.
Fat gets much of the blame for heartburn, yet when volunteers ate meals of the same size, one rich in fat and one low in it, their reflux was the same after both. The size of the meal made the difference. So the experiment is an easy one to run: cut the bread, pasta, sugar and snacks for two weeks and watch what happens at night.
Train the muscle around the valve
Around the valve sits a helper that rarely gets a mention. The diaphragm, the big breathing muscle under the lungs, wraps around the food pipe exactly where the valve sits, squeezing it shut from outside. Like any muscle, it can be trained. When adults with reflux practised slow belly breathing for four weeks, the time acid spent in their food pipe roughly halved, and those who kept it up were taking about a quarter as many acid tablets nine months later. Breathing slowly into the belly straight after a meal cut the number of reflux episodes in the hours that followed.
Belly breathing means letting each breath in fill the belly so it rises while the chest stays still, then letting the air out slowly. It costs nothing, and it fits into the quiet minutes after dinner.
The pill that makes it come back
Acid-blocking tablets, the kind taken daily for weeks or months, are effective at reducing acid and letting an inflamed food pipe heal. They also have a surprising side effect when you stop them. When healthy volunteers with no heartburn at all took them for two months and then stopped, nearly half developed heartburn or acid symptoms in the following weeks, compared with far fewer of those given a dummy pill. The stomach had adapted by building up its acid-making capacity, and it overshot when the tablets were withdrawn.
That rebound feels exactly like the old reflux coming back, which is why stopping often feels impossible and the tablets seem to be needed forever. The overshoot is temporary, though, and knowing the burning is the stomach readjusting makes it much easier to ride out. For anyone who wants to come off them, doing it gradually, with support from whoever prescribes them, makes it far more likely to work. Long-term use also comes with its own costs, including lower absorption of vitamin B12 and magnesium, something to weigh up after years on them.
When the problem is too little acid
Heartburn feels like too much acid, so the natural answer seems to be less. Yet people whose stomachs make almost no acid, because of a form of stomach inflammation that wears away the acid-making cells, still get heartburn and regurgitation. Acid-blocking tablets leave about two in three of them with no relief at all, since there's so little acid to block. For them, the logical move runs the other way: putting acid back.
I know this one first-hand. As a child I had stomach problems, and what cured them was adding stomach acid.
Stomach acid does far more than burn. It starts breaking down protein, frees B12 and minerals from food, and kills many of the bacteria swallowed with every meal. Low acid becomes more common with age, with years of acid blockers, and with a long-running infection by H. pylori, a common stomach bug.
A few clues point to low acid: heartburn that acid blockers never touched, a low B12 result on a blood test, or a past H. pylori infection. A quick breath or stool test checks for H. pylori, and clearing the infection is worth doing for its own sake, since the same bug is behind many stomach ulcers.
Putting acid back is an old idea. In the first half of the twentieth century, hydrochloric acid taken with meals was a common aid to digestion. Today it comes as betaine HCl, often paired with pepsin, the stomach's own protein-digesting enzyme, as in Thorne's capsules. Taken with food, it makes the stomach strongly acidic again within minutes and keeps it that way for about an hour. Its effect on heartburn is still untested, so treat it as an experiment you run on yourself.
Run it carefully. Skip it if you have a stomach ulcer or take anti-inflammatory painkillers or steroid tablets, which already strain the stomach lining. Stop at once if it causes a warm or burning feeling, a sign the lining is irritated and needs to heal first.
Gentle helpers
Ginger, chamomile tea and a lighter evening meal are safe, pleasant ways to calm an unsettled stomach, even though the evidence for them in reflux is modest. A cup of after dinner also helps mark the end of eating for the day. Liquorice-derived remedies are common too, but whole liquorice can raise blood pressure, so the deglycyrrhizinated kind, sold as DGL, is the safer form for anyone who uses it.
When heartburn needs checking
Heartburn has nothing to do with the heart. The name comes from where it's felt, right behind the breastbone, over the heart, and that shared spot is why the two get confused. Chest pain that spreads to the arm, jaw or back, or comes with breathlessness or sweating, needs emergency help straight away, since it can be the heart and not the stomach.
Get checked promptly if food feels as though it's sticking on the way down, if swallowing hurts, if you're losing weight without trying, vomiting, or bringing up blood or material that looks like coffee grounds, if your stools turn black, or if heartburn starts for the first time after your mid-fifties. Years of heartburn most weeks earn a check of their own, since long-running reflux can change the lining of the food pipe.
Settle it at the source
Heartburn returns when the valve keeps meeting the same pressures: big late dinners, starchy and sugary food, a tight waistband, the weight around the middle. The tablets can lock the cycle in, and for some, the fire started with a stomach running short of acid. Ease the pressure, give the stomach what it's missing, and the valve has a far easier job.
Start tonight with the simplest change: finish eating three hours before bed, and sleep on your left side. That alone can turn a night of pillows and antacids back into an ordinary night's sleep.
Wondering which foods are behind the gut trouble, beyond the burn? Foods That Upset Your Gut: What's Real and What's Personal — what's hard on every gut, what's personal to you, and why some feel better eating meat alone.
Lying awake long after the burning has settled? Chronic Insomnia: Why Trying Harder Keeps You Awake — why effort keeps you awake, and how to retrain the bed for sleep.
Know someone who keeps a packet of antacids on the bedside table? Send them this. The change that helps might be as simple as when dinner ends.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If you're pregnant, have a stomach ulcer or take any medicine, check every supplement with whoever prescribes your medicines before starting it.
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