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Rennie Orange Flavour - 48 Tablets

Rennie Orange Flavour - 48 Tablets

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  • ✔️ Neutralises excess stomach acid fast for heartburn relief
  • ✔️ Dual antacid formula: calcium carbonate and magnesium carbonate
  • ✔️ Orange-flavoured chewable tablets — no water needed
  • ✔️ Suitable for adults and children aged 12 and over
  • ✔️ 48-tablet pack offers great value for regular sufferers

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Are Rennie Antacid Tablets Right for Your Heartburn?

 

That familiar burning feeling creeping up your chest after a meal — most of us know it all too well. Rennie antacid tablets have been a trusted household name in the UK for decades, offering fast-acting relief from heartburn, indigestion, and acid reflux. This orange-flavoured pack of 48 tablets is a convenient, great-value option for anyone who wants reliable symptom relief without needing a prescription. At just £2.99, it's one of the most accessible antacid options available. If you're looking for more digestive health products, browse our full indigestion collection at Cured Pharmacy.

Heartburn is extremely common in the UK. The NHS estimates that around one in five people experience it regularly. It occurs when stomach acid travels back up into the oesophagus, causing that characteristic burning discomfort. Rennie Orange Flavour tablets are designed to tackle this at the source — quickly and without fuss.

 

How Do Rennie Orange Flavour Tablets Work?

 

Rennie works through a straightforward chemical process. Each tablet contains two active antacid ingredients that neutralise excess stomach acid on contact. There's no waiting around — the action begins as soon as you chew the tablet.

  • Calcium carbonate (680 mg per tablet): Reacts directly with hydrochloric acid in the stomach to form calcium chloride, water, and carbon dioxide, raising the stomach's pH.
  • Heavy magnesium carbonate (80 mg per tablet): Works alongside calcium carbonate to provide a balanced antacid effect, helping to prevent the rebound acidity that can sometimes occur with calcium-only antacids.
  • Chewable format: Chewing the tablet increases the surface area of the active ingredients, allowing them to mix with stomach contents more rapidly than a swallowed tablet would.
  • Orange flavour: Makes the tablets more palatable, which can be particularly helpful if you need to take them regularly after meals.

 

Who Should Use Rennie Orange Flavour Tablets?

 

These tablets are suitable for a wide range of adults and older children. They're particularly useful for people who experience occasional heartburn or indigestion triggered by food, drink, or lifestyle factors. That said, they're not appropriate for everyone.

Rennie Orange Flavour tablets are generally suitable for:

  • Adults and children aged 12 and over experiencing occasional heartburn or acid indigestion
  • Pregnant women suffering from pregnancy-related heartburn (always check with your midwife or GP first)
  • People who prefer a chewable, flavoured tablet over liquid antacid preparations
  • Those who need a portable, discreet option to carry in a bag or keep at their desk

They are not suitable for children under 12, or for people with hypercalcaemia (high blood calcium levels) or hypophosphataemia (low phosphate levels). Always read the label carefully before use.

 

How Do Rennie Tablets Compare to Other Antacid Options?

 

Feature Rennie Orange Flavour 48 Tablets Gaviscon Advance Liquid
Mechanism Neutralises stomach acid (antacid) Forms a raft on stomach contents (alginate + antacid)
Format Chewable tablet Liquid suspension
Portability Highly portable — tablet pack Less portable — liquid bottle
Suitable for pregnancy Generally yes (seek advice) Generally yes (seek advice)

 

Is Rennie Orange Flavour Suitable for Long-Term Use?

 

Rennie antacid tablets are intended for short-term, symptomatic relief. If you find yourself reaching for them every day, or if your symptoms persist beyond seven days, it's important to speak to your GP. Persistent heartburn can sometimes be a sign of gastro-oesophageal reflux disease (GORD) or, in rare cases, something that needs further investigation. The NHS advises that anyone with frequent or severe symptoms should seek medical advice rather than relying on over-the-counter antacids long-term.

It's also worth knowing that calcium carbonate — one of the active ingredients — can contribute to elevated calcium levels if taken in very large amounts over a prolonged period. This is another reason to stick to the recommended dose and duration. If you're managing a related digestive condition such as IBS, you might also find our IBS and cramps collection helpful for additional support options.

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.

Rennie Orange Flavour 48 Tablets specifications
Treatment category Heartburn & Indigestion / Antacids
Mechanism of action Neutralises excess gastric acid via calcium carbonate and magnesium carbonate
Effective for Heartburn, acid indigestion, dyspepsia, acid reflux symptoms
Suitable for Adults and children aged 12 and over
Active ingredient Calcium carbonate 680 mg, Heavy magnesium carbonate 80 mg (per tablet)
Pack size 48 tablets
UK classification General Sale List (GSL)
Drug class Antacid
Preparation Chewable tablet
Route of administration Oral

Specifications of Rennie Orange Flavour 48 Tablets

 

What Is Rennie Orange Flavour and What Is It Used For?

 

Rennie Orange Flavour 48 Tablets is an over-the-counter antacid medicine used to relieve the symptoms of heartburn, acid indigestion, and dyspepsia (upset stomach). It contains two active antacid ingredients — calcium carbonate and heavy magnesium carbonate — which work together to neutralise excess stomach acid. The tablets are chewable and orange-flavoured, making them easy and pleasant to take. They are classified as a General Sale List (GSL) medicine in the UK, meaning you can buy them without a prescription from pharmacies and supermarkets.

Heartburn occurs when acid from the stomach rises into the oesophagus, causing a burning sensation in the chest or throat. Indigestion (dyspepsia) can cause bloating, discomfort, or a feeling of fullness after eating. Rennie antacid tablets are designed to provide symptomatic relief from both of these common conditions.

 

What Do You Need to Know Before Using Rennie Orange Flavour?

 

Before taking these tablets, it's important to check whether they are appropriate for you. Do not take Rennie Orange Flavour if any of the following apply:

  • You are allergic to calcium carbonate, heavy magnesium carbonate, or any other ingredient in the tablets
  • You have hypercalcaemia (high levels of calcium in your blood)
  • You have hypophosphataemia (low levels of phosphate in your blood)
  • You have severe kidney disease or kidney failure
  • You are under 12 years of age
  • You have been told by a doctor to follow a low-calcium diet

Speak to your pharmacist or GP before taking Rennie if you have kidney problems, are pregnant or breastfeeding, or are taking other medicines regularly.

Drug interactions — take at least 2 hours apart from:

  • Tetracycline antibiotics (e.g. doxycycline) — antacids can reduce their absorption
  • Bisphosphonates (e.g. alendronic acid) — used for osteoporosis
  • Thyroid medicines (e.g. levothyroxine)
  • Some antifungal medicines (e.g. ketoconazole)
  • Iron supplements — absorption may be reduced

 

How Should You Use Rennie Orange Flavour Tablets?

 

Always use this medicine exactly as described in the patient information leaflet or as directed by your pharmacist. Do not exceed the stated dose.

  1. Chew or suck 2 tablets when symptoms occur — do not swallow them whole.
  2. Take after meals and at bedtime, or whenever heartburn or indigestion symptoms arise.
  3. Allow the tablet to dissolve fully in your mouth before swallowing.
  4. If symptoms persist after taking the tablets, do not take additional doses beyond the maximum daily limit.
  5. Do not take more than 16 tablets in any 24-hour period.
  6. Do not use for more than 7 consecutive days without consulting a doctor.
Indication Age Group Dose Frequency
Heartburn / Indigestion Adults & children 12+ 2 tablets After meals & at bedtime; max 16 tablets/24 hrs
Not recommended Under 12 years

 

What Are the Possible Side Effects of Rennie Orange Flavour?

 

Like all medicines, Rennie Orange Flavour can cause side effects, although not everyone experiences them. Most people tolerate these tablets well when taken at the recommended dose for a short period.

Common side effects (may affect up to 1 in 10 people):

  • Constipation — more likely with calcium carbonate-containing antacids
  • Diarrhoea — more likely with magnesium-containing antacids
  • Flatulence (wind) — due to carbon dioxide produced during the neutralisation reaction

Less common side effects (may affect up to 1 in 100 people):

  • Nausea or stomach discomfort
  • Hypercalcaemia (raised blood calcium) — particularly with prolonged high-dose use; symptoms include thirst, frequent urination, muscle weakness, or confusion
  • Milk-alkali syndrome — a rare condition associated with excessive calcium carbonate intake alongside dairy products

If you experience any signs of a serious allergic reaction — such as swelling of the face, lips, or throat, difficulty breathing, or a severe skin rash — stop taking the tablets immediately and seek urgent medical attention. You can also find additional support for related digestive symptoms in our sickness and nausea collection.

 

How Should You Store Rennie Orange Flavour Tablets?

 

Correct storage helps maintain the quality and effectiveness of the tablets throughout their shelf life.

  • Store below 25°C in a dry place — avoid bathrooms or areas with high humidity
  • Keep the tablets in their original packaging to protect from moisture
  • Keep out of the sight and reach of children
  • Do not use after the expiry date printed on the pack
  • Do not dispose of medicines via wastewater or household waste — return unused tablets to your pharmacy

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 Rennie Orange Flavour tablets online in the UK?

You can buy Rennie Orange Flavour 48 Tablets online from Cured Pharmacy, a UK GPhC-registered online pharmacy, for just £2.99. No prescription is required as these are a General Sale List (GSL) medicine. Simply add them to your basket and choose your preferred delivery option for fast, discreet dispatch.

How do Rennie antacid tablets work in the body?

Rennie tablets contain calcium carbonate and heavy magnesium carbonate, which chemically neutralise excess hydrochloric acid in the stomach. This raises the pH of the stomach contents, reducing the burning sensation in the oesophagus and chest. The chewable format means the active ingredients get to work quickly — usually within minutes of taking the tablet.

How do I use Rennie Orange Flavour tablets step by step?

Chew or suck 2 tablets when your symptoms occur — do not swallow them whole. Take them after meals and at bedtime, or whenever heartburn or indigestion strikes. Do not exceed 16 tablets in any 24-hour period, and do not use for more than 7 consecutive days without speaking to a doctor or pharmacist.

What is the correct dose of Rennie for adults?

The recommended dose for adults and children aged 12 and over is 2 tablets per dose, chewed or sucked. You can take them after meals and at bedtime, or as needed when symptoms arise. The maximum dose is 16 tablets in 24 hours — never exceed this amount.

When is the best time to take Rennie tablets?

Rennie tablets work best when taken after meals and at bedtime, as these are the times when stomach acid production tends to peak and reflux is most likely to occur. You can also take them as soon as symptoms appear at any other time of day. Taking them on an empty stomach is less effective as there is less acid to neutralise.

Can I take Rennie tablets during pregnancy?

Rennie is generally considered suitable for occasional use during pregnancy to relieve heartburn, which is very common — particularly in the second and third trimesters. However, you should always speak to your midwife, GP, or pharmacist before taking any medicine while pregnant, to make sure it is appropriate for your individual circumstances.

Are Rennie tablets safe to take while breastfeeding?

Rennie is generally considered low risk during breastfeeding, as the active ingredients are poorly absorbed into the bloodstream and are unlikely to pass into breast milk in significant amounts. That said, it is always sensible to check with your pharmacist or GP before taking any medicine while breastfeeding, just to be sure.

What are the side effects of Rennie antacid tablets?

Most people tolerate Rennie well at the recommended dose. The most commonly reported side effects include constipation, diarrhoea, and flatulence. Prolonged or excessive use can, in rare cases, lead to raised blood calcium levels (hypercalcaemia), so it is important to stick to the recommended dose and duration.

Can Rennie tablets interact with other medicines?

Yes — Rennie can interfere with the absorption of certain medicines, including tetracycline antibiotics, bisphosphonates (used for osteoporosis), levothyroxine (thyroid medicine), some antifungals, and iron supplements. To avoid this, leave at least 2 hours between taking Rennie and any of these medicines. Always tell your pharmacist about all medicines you are taking.

Who should not take Rennie Orange Flavour tablets?

Rennie Orange Flavour is not suitable for children under 12, people with hypercalcaemia (high blood calcium), hypophosphataemia (low blood phosphate), or severe kidney disease. It should also be avoided by anyone following a medically prescribed low-calcium diet. If you are unsure whether Rennie is right for you, speak to your pharmacist before taking it.

How long can you take Rennie tablets for?

Rennie is intended for short-term use only — no more than 7 consecutive days. If your heartburn or indigestion symptoms persist beyond this, keep returning, or are getting worse, you should see your GP. Persistent symptoms may indicate an underlying condition such as gastro-oesophageal reflux disease (GORD) that requires a different approach to treatment.

What happens if I take too many Rennie tablets?

Taking more than the recommended dose of Rennie can lead to side effects including nausea, vomiting, and in more serious cases, raised blood calcium levels (hypercalcaemia). If you think you or someone else has taken too many tablets, contact NHS 111 or go to your nearest A&E department immediately. Always keep medicines out of reach of children.

What are the alternatives to Rennie antacid tablets?

There are several other antacid options available if Rennie is not suitable for you, including Gaviscon (which uses an alginate raft mechanism), Tums (calcium carbonate only), and Maalox (aluminium and magnesium hydroxide). For more persistent symptoms, a GP may recommend a proton pump inhibitor (PPI) such as omeprazole. You can also explore our full indigestion range for other options.

Can children take Rennie Orange Flavour tablets?

Rennie Orange Flavour tablets are not recommended for children under 12 years of age. For children aged 12 and over, the adult dose applies — 2 tablets chewed or sucked as needed, up to a maximum of 16 tablets in 24 hours. If your child is under 12 and experiencing digestive symptoms, speak to your GP or pharmacist for age-appropriate advice. You may also find our baby and toddler collection useful for younger children's health needs.

What is the latest research on antacid tablets like Rennie?

Calcium carbonate and magnesium carbonate antacids have a well-established safety and efficacy profile supported by decades of clinical use. Current NHS guidance continues to recommend antacids as a first-line option for mild, occasional heartburn and indigestion. For more frequent or severe symptoms, clinical guidelines suggest stepping up to H2 receptor antagonists or proton pump inhibitors under medical supervision.

How Should You Use Rennie Orange Flavour Tablets?

Rennie Orange Flavour tablets are designed to be chewed or sucked — never swallowed whole. Chewing the tablet allows the active ingredients to mix with saliva and reach the stomach quickly, where they can begin neutralising acid straight away. Follow these steps each time you take a dose:

Do not crush the tablets and mix them into food or drink — this is not the intended method of administration and may affect how well they work.

What Is the Correct Dose of Rennie Orange Flavour?

The correct dose depends on your age. Always follow the dosage instructions on the pack or as directed by your pharmacist. Never exceed the maximum daily dose, as doing so increases the risk of side effects including raised blood calcium levels.

If a single dose does not fully relieve your symptoms, do not take extra tablets beyond the recommended amount. Instead, speak to your pharmacist for further advice.

When Is the Best Time to Use Rennie Orange Flavour?

Rennie tablets are most effective when taken after meals and at bedtime. Stomach acid production tends to increase after eating and when you lie down, which is why these are the times when heartburn and indigestion are most likely to flare up. Taking the tablets at these moments means the antacid ingredients are present in the stomach when they are needed most. You can also take them at any other time of day as soon as symptoms appear — there is no need to wait.

How Long Can You Use Rennie Orange Flavour For?

Rennie Orange Flavour tablets are intended for short-term, symptomatic relief only. You should not use them for more than 7 consecutive days without consulting a doctor or pharmacist. If your symptoms keep returning, are getting worse, or are accompanied by other symptoms such as difficulty swallowing, unexplained weight loss, or persistent vomiting, you should seek medical advice promptly. These could be signs of a more serious underlying condition that requires proper investigation and treatment beyond an over-the-counter antacid.

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

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What Are the Most Common Side Effects of Rennie Orange Flavour?

Most people who take Rennie Orange Flavour tablets at the recommended dose for a short period do not experience significant side effects. However, as with any medicine, some people may notice unwanted effects. The most commonly reported ones are related to the digestive system.

  • Constipation — calcium carbonate can slow bowel movements in some people
  • Diarrhoea — magnesium carbonate has a mild laxative effect in some individuals
  • Flatulence (wind) — a natural by-product of the acid-neutralisation reaction in the stomach

What Are the Less Common Side Effects of Rennie Orange Flavour?

Less common side effects are more likely to occur if you take Rennie in higher doses than recommended or for longer than advised. If you notice any of the following, stop taking the tablets and speak to your pharmacist or GP.

  • Nausea or stomach discomfort
  • Hypercalcaemia (raised blood calcium) — symptoms include increased thirst, frequent urination, muscle weakness, confusion, or fatigue
  • Milk-alkali syndrome — a rare condition caused by excessive calcium carbonate intake alongside high dairy consumption; symptoms include nausea, vomiting, and confusion
  • Rebound acid hypersecretion — the stomach may temporarily produce more acid after stopping antacids, particularly with prolonged use

What Are the Serious Side Effects of Rennie Orange Flavour?

Serious side effects from Rennie are rare when the tablets are used correctly and for short periods. However, you should seek urgent medical attention if you experience any signs of a serious allergic reaction (anaphylaxis), which can include swelling of the face, lips, tongue, or throat, difficulty breathing, a rapid heartbeat, or a severe skin rash. These reactions are very uncommon but require immediate medical care.

Prolonged, high-dose use of calcium-containing antacids has been associated with hypercalcaemia and, in rare cases, kidney stones. This is why sticking to the recommended dose and duration is so important.

What Should You Do If You Experience Side Effects?

If you notice any side effects that concern you, stop taking Rennie and speak to your pharmacist or GP as soon as possible. For mild digestive side effects such as constipation or wind, these usually resolve on their own once you stop taking the tablets. If you suspect you have taken too much, contact NHS 111 immediately or go to your nearest A&E department. You can also report suspected side effects directly to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.

Can Rennie Orange Flavour Interact With Other Medicines?

Yes — Rennie can affect how certain other medicines are absorbed by the body. The calcium and magnesium in the tablets can bind to some medicines in the gut, reducing the amount that enters your bloodstream. To avoid this, always leave at least 2 hours between taking Rennie and any of the following:

  • Tetracycline antibiotics (e.g. doxycycline, tetracycline)
  • Bisphosphonates (e.g. alendronic acid, risedronate) — used for osteoporosis
  • Levothyroxine — used for an underactive thyroid
  • Ketoconazole and other azole antifungals
  • Iron supplements
  • Some HIV medicines

Always tell your pharmacist about all medicines, supplements, and herbal remedies you are taking before starting Rennie.

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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