Take Gaviscon after every meal and once more at bedtime — up to 4 doses a day. Here is the pharmacist-recommended schedule:
Time
Take?
Why
After breakfast
✓
Blocks post-meal acid
After lunch
✓
Blocks post-meal acid
After dinner
✓
Dinner is usually heaviest — most acid
At bedtime
✓
Lying flat makes reflux easier
Before meals / empty stomach
✗
Raft forms poorly and empties fast
Why After Meals — Not Before
This is the most common misunderstanding — Gaviscon is not a before-meal stomach-coating medicine.
Its mechanism is the alginate raft: on contact with acid the medicine gels and floats on top of the food in your stomach, sealing the stomach–oesophagus junction.
Taken after a meal → food supports the raft in the right position for its full duration
Taken on an empty stomach → nothing to float on; the stomach empties the medicine quickly and the effect is much shorter
Standard dose for adults and children 12 and over:
Form
Dose
How to take
Best for
Liquid (150 ml bottle)
10–20 ml
Shake well, measure and take
Regular home use
Sachet
1–2 sachets
Knead, tear and take directly — no water needed
Travel and carry
Chewable tablets
2–4 tablets
Chew thoroughly before swallowing — never whole
Pocket carry
The liquid bottle most commonly sold in Thailand is Gaviscon Dual Action 150 ml — always check the expiry date and FDA registration number on the label.
How Fast It Works and How Long It Lasts
It starts within minutes — the raft forms as soon as it meets stomach acid, no absorption needed — and controls symptoms for about 4 hours, covering the post-meal window when reflux is most common.
Taken at bedtime, the raft blocks acid through the first hours of sleep, reducing midnight heartburn and morning regurgitation.
Missed a Dose or Took Too Much?
Missed dose
Just take it after your next meal — do not double up. Gaviscon is symptomatic relief, not a medicine that maintains blood levels.
Too much
Usually not dangerous — you may get bloating, belching or fullness. Drink water and observe. If anything unusual persists, such as repeated vomiting, contact a doctor or pharmacist.
Taking It With Other Medicines — How Long to Space
Leave about a 2-hour gap — Gaviscon's antacids change stomach acidity and can reduce absorption of some medicines. Common ones we see at the pharmacy:
Tetracycline and quinolone antibiotics (e.g. doxycycline, ciprofloxacin) — bind with calcium, sharply reducing absorption
Iron supplements — absorb poorly in low acid
Thyroid medicine (levothyroxine) — needs clear spacing
PPIs (e.g. omeprazole) can be used together — different mechanisms: the PPI reduces acid production long-term while Gaviscon handles breakthrough symptoms. Always tell your doctor or pharmacist what you take.
How Long Can You Use It — When to See a Doctor
Gaviscon is designed for occasional symptoms. Signs it is time to see a doctor:
No improvement within 7 days of use
You need it continuously for over 2 weeks to stay comfortable
Heartburn more than twice a week ongoing — meets GERD criteria and deserves proper diagnosis
Alarm symptoms: difficulty swallowing, unexplained weight loss, vomiting blood, black stools — see a doctor immediately
Generally usable — Gaviscon acts locally in the stomach without entering the bloodstream, making it a widely used option for pregnancy heartburn. Always consult your doctor before starting, especially with a high-risk pregnancy or sodium restriction.
Children
Children 12 and over can use the adult dose. Under 12, only on a doctor's or pharmacist's advice.
Frequently Asked Questions
After meals — the alginate raft needs food and acid in the stomach to form and float on. Before meals or on an empty stomach the effect is much shorter.
Yes for sudden symptoms, but the effect is shorter — when possible, follow the after-meals and bedtime schedule.
Knead the sachet to mix, tear and take directly — no water needed. 1–2 sachets per dose.
Yes — chew thoroughly before swallowing. The medicine must break down in the stomach to form the raft. Never swallow whole.
Up to 4 doses daily — after 3 meals and at bedtime. Do not exceed the label dose.
A small sip is fine, but avoid drinking a lot of water straight away — it dilutes the newly formed raft.
Avoid large amounts of milk with the dose — the combined calcium load can raise side-effect risk. Space them 1–2 hours apart.
Yes — different mechanisms: the PPI reduces acid production while Gaviscon handles breakthrough symptoms. Tell your doctor/pharmacist. More: Acid Reflux Medicines Explained
⚠️ Disclaimer
The information on this page is for general informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment from a qualified doctor or pharmacist. If you have any questions about your symptoms or medication, always consult a doctor or pharmacist first.
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