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Acidex Original Sugar Free Oral Suspension Aniseed- 500ml

Acidex Original Sugar Free Oral Suspension Aniseed- 500ml

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  • ✔️ Relieves heartburn and acid reflux symptoms after meals
  • ✔️ Forms a protective raft to prevent stomach acid rising
  • ✔️ Sugar-free formula suitable for those managing sugar intake
  • ✔️ Aniseed-flavoured liquid for easy, pleasant administration
  • ✔️ 500ml bottle provides extended supply for ongoing relief

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What Is Acidex Oral Suspension and How Does It Help Heartburn?

 

Heartburn and acid reflux are incredibly common — and if you've ever felt that burning sensation creeping up your chest after a meal, you'll know just how uncomfortable it can be. Acidex oral suspension is an alginate-based antacid liquid designed to provide fast, effective relief from heartburn, acid reflux, and indigestion. Available in a pleasant aniseed flavour and completely sugar free, this 500ml bottle is a practical choice for adults who need reliable, everyday symptom management. You can browse our full range of indigestion treatments if you'd like to compare your options.

Acidex Original Sugar Free Oral Suspension contains three active ingredients: sodium alginate, sodium bicarbonate, and calcium carbonate. Together, these work to neutralise stomach acid and create a physical barrier that stops acid from rising into the oesophagus. It's classified as a general sale medicine in the UK, meaning you can purchase it without a prescription.

 

How Does Acidex Oral Suspension Work in the Stomach?

 

The mechanism behind Acidex is elegantly straightforward. Rather than simply suppressing acid production (as proton pump inhibitors do), it works by forming a protective raft on top of stomach contents. Here's how that process unfolds:

  • Sodium alginate reacts with stomach acid to form a thick, viscous gel.
  • Sodium bicarbonate generates carbon dioxide, which causes the gel to float — creating a "raft" on the surface of stomach contents.
  • Calcium carbonate reinforces the raft and also contributes to acid neutralisation.
  • The raft physically prevents acidic stomach contents from refluxing back up into the oesophagus.

This raft-forming action means Acidex targets the root cause of reflux symptoms rather than just masking discomfort. It's particularly useful after meals, when acid production is at its highest and reflux is most likely to occur.

 

Who Is Acidex Oral Suspension Suitable For?

 

Acidex is suitable for most adults and children aged 12 and over who experience occasional or frequent heartburn, acid reflux, or indigestion. Because it's sugar free, it's also a sensible option for people managing their sugar intake. That said, it does contain sodium, so those on a sodium-restricted diet should check with their pharmacist first.

It may be particularly appropriate for:

  • Adults experiencing heartburn after meals or at night.
  • People who prefer a liquid antacid over tablets or capsules.
  • Those who want a sugar-free formulation.
  • Individuals who find proton pump inhibitors unsuitable or prefer an alginate-based approach.

 

How Does Acidex Compare to Other Antacid Suspensions?

 

Feature Acidex Original Sugar Free Suspension Gaviscon Advance Liquid
Active ingredients Sodium alginate, sodium bicarbonate, calcium carbonate Sodium alginate, potassium bicarbonate
Sugar free Yes Yes (some variants)
Flavour Aniseed Peppermint or aniseed
Pack size 500ml 150ml or 300ml
Price (approx.) £6.99 Higher per ml cost

 

Is Acidex Oral Suspension Suitable for Long-Term Use and How Should It Be Stored?

 

Acidex oral suspension is intended for short-term relief of reflux and heartburn symptoms. If you find yourself relying on it daily for more than two weeks, it's worth speaking to your GP — persistent symptoms can sometimes indicate an underlying condition that warrants further investigation. The NHS advises that ongoing acid reflux should be assessed by a healthcare professional to rule out conditions such as gastro-oesophageal reflux disease (GORD).

Store the bottle below 25°C and keep it out of direct sunlight. Do not freeze. Always keep medicines out of the reach and sight of children. Once opened, check the product label for any specific in-use storage guidance. If you're also managing related digestive concerns, our IBS and cramps collection may have additional products worth exploring.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

Acidex Original Sugar Free Oral Suspension Aniseed 500ml specifications
Treatment category Antacid / Alginate reflux suppressant
Mechanism of action Forms a raft on stomach contents to prevent acid reflux; neutralises excess stomach acid
Effective for Heartburn, acid reflux, indigestion
Suitable for Adults and children aged 12 and over
Active ingredients Sodium alginate 250mg/5ml, Sodium bicarbonate 133.5mg/5ml, Calcium carbonate 80mg/5ml
Pack size 500ml
UK classification General Sale List (GSL)
Drug class Alginate antacid
Preparation Oral suspension
Route of administration Oral

Specifications of Acidex Original Sugar Free Oral Suspension Aniseed 500ml

 

What Is Acidex Original Sugar Free Oral Suspension and What Is It Used For?

 

Acidex Original Sugar Free Oral Suspension is an over-the-counter alginate antacid used to relieve the symptoms of heartburn, acid reflux, and indigestion. It works by forming a protective gel raft on top of stomach contents, preventing acidic fluid from rising into the oesophagus. The aniseed-flavoured liquid is sugar free, making it suitable for people who need to limit their sugar intake. It is available without a prescription and is classified as a General Sale List (GSL) medicine in the UK.

Acid reflux occurs when stomach acid travels back up into the oesophagus, causing a burning sensation in the chest or throat. The NHS notes that this is a very common condition, often triggered by certain foods, lying down after eating, or being overweight. Acidex oral suspension addresses these symptoms directly, offering relief that typically begins within minutes of taking a dose.

 

What Do You Need to Know Before Using Acidex Oral Suspension?

 

Before using Acidex, it's important to check whether it's appropriate for you. Do not use this product if any of the following apply:

  • You are allergic to any of the active or excipient ingredients.
  • You have been advised to follow a low-sodium diet (each 10ml dose contains a significant amount of sodium).
  • You have severely impaired kidney function, unless advised by a doctor.
  • The patient is a child under 12 years of age, unless directed by a healthcare professional.
  • You have phenylketonuria — check the full ingredients list for any relevant excipients.

You should also be aware of potential interactions with other medicines:

  • Acidex may reduce the absorption of certain medicines, including some antibiotics, thyroid medicines, and bisphosphonates.
  • Leave a gap of at least 2 hours between taking Acidex and any other oral medication.
  • Always inform your pharmacist or GP of all medicines you are currently taking, including herbal remedies and supplements.

 

How Should You Use Acidex Oral Suspension?

 

Always use Acidex exactly as described in the patient information leaflet or as directed by your pharmacist. Shake the bottle well before each use to ensure the suspension is evenly mixed.

  1. Shake the bottle thoroughly before opening.
  2. Measure the correct dose using the measuring cup or spoon provided.
  3. Take the dose after meals and at bedtime.
  4. Swallow the suspension directly — do not dilute with water.
  5. Replace the cap securely after use and store as directed.
Indication Age Group Dose Frequency
Heartburn / acid reflux Adults and children 12+ 10–20ml After meals and at bedtime (up to 4 times daily)
Indigestion Adults and children 12+ 10–20ml After meals and at bedtime (up to 4 times daily)
Children under 12 Under 12 years Not recommended Seek medical advice

If you are unsure about the correct dose, speak to your pharmacist before use. You might also find it helpful to explore our sickness and nausea range if you experience associated digestive symptoms alongside your reflux.

 

What Are the Possible Side Effects of Acidex Oral Suspension?

 

Like all medicines, Acidex can cause side effects, although not everyone experiences them. Most people tolerate it well. If you do notice any unusual symptoms, stop using the product and consult your pharmacist or GP.

Common side effects:

  • Bloating or a feeling of fullness
  • Flatulence (wind)
  • Mild nausea

Less common side effects:

  • Constipation or diarrhoea
  • Hypersensitivity reactions (rash, itching) — rare
  • Oedema (fluid retention) in patients with sodium sensitivity — seek medical advice promptly

If you experience any signs of a serious allergic reaction — such as swelling of the face, lips, or throat, difficulty breathing, or a severe rash — stop use immediately and seek emergency medical attention.

 

How Should You Store Acidex Oral Suspension?

 

Correct storage helps maintain the product's effectiveness and safety throughout its shelf life. Follow these guidelines:

  • Store below 25°C in a cool, dry place.
  • Do not freeze the suspension.
  • Keep away from direct sunlight and heat sources.
  • Keep the bottle tightly closed when not in use.
  • Keep out of the reach and sight of children at all times.
  • Do not use after the expiry date printed on the label.
  • Do not dispose of medicines via wastewater or household waste — return unused medicine to your pharmacist for safe disposal.

If you're managing multiple digestive health concerns, our constipation collection offers a range of products that may complement your digestive health routine.

Written and reviewed by our qualified team

Your safety and success are our highest priorities. Our medical team rigorously evaluates every product and piece of advice we provide, ensuring you receive only the most effective, science-backed solutions available.

Frequently Asked Questions

Where can I buy Acidex oral suspension online in the UK?

You can buy Acidex Original Sugar Free Oral Suspension Aniseed 500ml directly from Cured Pharmacy, a GPhC-registered UK online pharmacy, for just £6.99. It's available without a prescription as an over-the-counter medicine. Simply add it to your basket and it will be dispatched to your door.

How does Acidex oral suspension work in the body?

Acidex works through a raft-forming mechanism: sodium alginate reacts with stomach acid to create a thick gel that floats on top of stomach contents, physically preventing acid from refluxing into the oesophagus. Sodium bicarbonate and calcium carbonate also help neutralise excess stomach acid. This dual action provides both a physical barrier and chemical neutralisation of acid.

How do I use Acidex oral suspension step by step?

Shake the bottle well before each use, then measure 10–20ml using the measuring cup provided. Take the dose after meals and at bedtime — swallow it directly without diluting. Replace the cap tightly after use and store the bottle below 25°C.

What is the correct dose of Acidex for adults?

The recommended adult dose is 10–20ml taken after meals and at bedtime, up to four times daily. You should not exceed this without speaking to a pharmacist or GP. If symptoms persist beyond two weeks, seek medical advice.

What is the best time to take Acidex oral suspension?

Acidex is most effective when taken after meals and at bedtime, as this is when acid production is highest and reflux is most likely to occur. Taking it at bedtime is particularly helpful if you experience night-time heartburn or wake with a sour taste in your mouth. Consistency with timing helps maximise the raft-forming effect.

Is Acidex oral suspension safe to take during pregnancy?

Heartburn is very common during pregnancy, and alginate-based antacids are sometimes recommended by healthcare professionals in this context. However, you should always speak to your midwife, GP, or pharmacist before taking any medicine during pregnancy, as individual circumstances vary. They can advise on the safest and most appropriate option for you.

What are the side effects of Acidex oral suspension?

Most people tolerate Acidex well, but some may experience bloating, flatulence, or mild nausea. Less commonly, constipation or diarrhoea may occur. If you notice any signs of an allergic reaction — such as swelling, rash, or difficulty breathing — stop use immediately and seek medical attention.

How do I manage side effects of Acidex oral suspension?

Mild side effects such as bloating or wind usually resolve on their own and don't require treatment. If you find the suspension causes digestive discomfort, try taking a smaller dose initially and building up gradually. Always speak to your pharmacist if side effects are persistent or troublesome.

Can I take Acidex with other medicines?

Acidex may reduce the absorption of certain medicines, including some antibiotics, thyroid medications, and bisphosphonates, if taken at the same time. It's recommended to leave a gap of at least 2 hours between Acidex and any other oral medication. Always tell your pharmacist about everything you're currently taking, including vitamins and supplements — you can browse our vitamins and supplements range for reference.

Who is eligible to use Acidex oral suspension?

Acidex is suitable for adults and children aged 12 and over who experience heartburn, acid reflux, or indigestion. It is not recommended for children under 12 without medical supervision. People on sodium-restricted diets or with severely impaired kidney function should consult a healthcare professional before use.

What happens if I miss a dose of Acidex?

If you forget to take a dose, simply take it as soon as you remember — unless it's nearly time for your next dose, in which case skip the missed one. Do not take a double dose to make up for a missed one. Acidex is taken as needed for symptom relief, so missing an occasional dose is unlikely to cause problems.

How long can you use Acidex oral suspension for?

Acidex is intended for short-term relief of heartburn and reflux symptoms. If you find you need to use it every day for more than two weeks, you should speak to your GP, as persistent symptoms may indicate an underlying condition such as GORD that requires further assessment. Long-term self-medication without medical review is not advisable.

What are the alternatives to Acidex oral suspension?

Common alternatives include other alginate-based suspensions such as Gaviscon Advance, or antacid tablets containing calcium carbonate or magnesium trisilicate. For more persistent symptoms, a GP may recommend a proton pump inhibitor (PPI) such as omeprazole. You can explore our full indigestion range to compare available options.

Is Acidex oral suspension sugar free?

Yes — Acidex Original Sugar Free Oral Suspension is specifically formulated without sugar, making it a suitable choice for people who need to manage their sugar intake, including those with diabetes. Always check the full ingredients list if you have specific dietary requirements or allergies. If you monitor your blood glucose, our diabetes monitoring collection may also be of interest.

What are the latest studies on alginate antacids like Acidex?

Alginate-based antacids have been studied extensively and are well-established in clinical practice for the management of gastro-oesophageal reflux. Research consistently supports their raft-forming mechanism as an effective approach to reducing acid reflux episodes. The BNF and NHS both recognise alginate preparations as a first-line option for symptomatic relief of heartburn and reflux.

How Should You Use Acidex Original Sugar Free Oral Suspension?

Using Acidex correctly ensures you get the most effective relief from heartburn and acid reflux. Always shake the bottle thoroughly before each use, as the suspension can settle between doses. Follow these steps each time you take a dose:

Do not use more than the recommended amount. If you are unsure about how to use this product, ask your pharmacist for guidance before starting.

What Is the Correct Dose of Acidex Oral Suspension?

The dose varies depending on age. Children under 12 should not use this product unless directed by a healthcare professional. Always refer to the patient information leaflet supplied with the product for full dosage guidance.

If you are unsure which dose is right for you, speak to your pharmacist before use. Never exceed the stated dose.

When Is the Best Time to Use Acidex Oral Suspension?

Acidex is most effective when taken after meals and at bedtime. This timing is important because acid production peaks after eating, and lying down at night can make reflux worse. Taking a dose at bedtime is particularly helpful if you experience night-time heartburn or wake with a sour taste in your mouth.

Try to take each dose consistently at the same times each day to maintain symptom control. If you experience breakthrough symptoms between doses, speak to your pharmacist rather than taking an extra dose without guidance.

How Long Can You Use Acidex Oral Suspension For?

Acidex is designed for short-term relief of heartburn, acid reflux, and indigestion. Most people use it for a few days to a couple of weeks to manage occasional or temporary symptoms. If you find that you need to use it every day for longer than two weeks, this is a sign that you should speak to your GP.

Persistent or worsening symptoms may indicate an underlying condition such as gastro-oesophageal reflux disease (GORD), which may require a different treatment approach. Your GP can assess your symptoms and recommend the most appropriate next steps, which may include lifestyle changes or prescription medication.

Do not exceed the recommended dose. If in doubt, speak to your pharmacist.

What Are the Most Common Side Effects of Acidex Oral Suspension?

Acidex is generally well tolerated by most people when used as directed. However, as with any medicine, some individuals may experience side effects. The most commonly reported ones are mild and tend to resolve on their own without any specific treatment.

  • Bloating or a feeling of fullness in the stomach
  • Flatulence (wind)
  • Mild nausea

These effects are largely related to the carbon dioxide produced when sodium bicarbonate reacts with stomach acid. If you find bloating particularly uncomfortable, try starting with a lower dose and increasing gradually.

What Are the Less Common Side Effects of Acidex Oral Suspension?

Less commonly, some people may experience digestive changes or other reactions. These are not expected in most users but are worth being aware of before you start treatment.

  • Constipation
  • Diarrhoea
  • Mild stomach discomfort
  • Skin rash or itching (hypersensitivity reaction — rare)

If you notice any of these less common effects and they persist or worsen, stop using the product and speak to your pharmacist or GP for advice.

What Are the Serious Side Effects of Acidex Oral Suspension?

Serious side effects from Acidex are rare, but you should be aware of them. Because the product contains sodium, people who are sensitive to sodium or who are on a sodium-restricted diet may experience fluid retention (oedema) — particularly with prolonged use or high doses. This can manifest as swelling in the ankles, feet, or hands.

In very rare cases, a severe allergic reaction (anaphylaxis) may occur. Signs include swelling of the face, lips, tongue, or throat, difficulty breathing, a rapid heartbeat, or a sudden drop in blood pressure. If you experience any of these symptoms, stop use immediately and call 999 or go to your nearest A&E department.

What Should You Do If You Experience Side Effects of Acidex?

For mild side effects such as bloating or wind, no specific action is usually needed — these typically resolve on their own. Reducing your dose slightly may also help. If side effects are persistent, troublesome, or unexpected, stop using Acidex and consult your pharmacist or GP before continuing.

You can also report suspected side effects directly to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. This helps the MHRA monitor the safety of medicines available in the UK and is open to both patients and healthcare professionals.

Can Acidex Oral Suspension Interact With Other Medicines?

Yes — Acidex can affect how other medicines are absorbed by the body. Because it alters the pH of the stomach and forms a physical gel layer, it may reduce the absorption of medicines taken at the same time. This includes some antibiotics (such as tetracyclines), thyroid medicines (such as levothyroxine), bisphosphonates, and certain antifungal medicines.

To minimise the risk of interactions, always leave a gap of at least 2 hours between taking Acidex and any other oral medication. Tell your pharmacist or GP about all medicines, vitamins, and herbal supplements you are currently taking before starting Acidex.

If you are concerned about any side effects, contact your pharmacist or GP immediately.

Patient Information Leaflet

Important - Before taking any medication, it is always important to read the Patient Information Leaflet (PIL)

Written and reviewed by our qualified team

GPhC Number: 2233073
Tarun Kumar

Reviewed by:

Tarun Kumar

Superintendent/ Clinical Lead

📖 Find out more about our team of medical content authors and how we ensure the accuracy of our content with our content guidelines.

Content last updated: 31 Mar 2025

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