Rybelsus (semaglutide) is an oral medication for type 2 diabetes that works by mimicking a natural gut hormone. Whilst not officially listed in product information, some patients report experiencing sulfur burps—belching with a distinctive rotten egg odour—after starting this treatment. This symptom may relate to how Rybelsus slows gastric emptying, potentially allowing increased hydrogen sulfide gas production during digestion. Understanding the connection between Rybelsus and digestive side effects, including sulfur burps, helps patients manage symptoms effectively whilst maintaining diabetes control. This article examines the evidence, mechanisms, and practical management strategies for this uncommon but troublesome side effect.

What Are Sulfur Burps and Why Do They Occur?

Sulfur burps are characterised by an unpleasant odour resembling rotten eggs when belching. This distinctive smell results from hydrogen sulfide gas produced during the digestive process. Whilst occasional burping is entirely normal and helps release swallowed air from the stomach, sulfur burps indicate specific digestive activity involving sulfur-containing compounds.

The production of hydrogen sulfide typically occurs when certain foods are broken down by bacteria in the gastrointestinal tract, predominantly in the intestines. Foods high in sulfur include red meat, poultry, eggs, dairy products, cruciferous vegetables (such as broccoli, cabbage, and Brussels sprouts), and foods containing sulphites. Individual sensitivity to these foods varies considerably.

Several factors may contribute to sulfur burps beyond dietary choices. These include:

• Gastrointestinal infections caused by bacteria such as Helicobacter pylori or parasites like Giardia lamblia

• Small intestinal bacterial overgrowth (SIBO), where excessive bacteria colonise the small intestine

• Delayed gastric emptying (gastroparesis), allowing food to remain in the digestive system longer

• Certain medications that affect digestive function or alter gut motility

• Food intolerances, particularly lactose intolerance or fructose malabsorption

Whilst sulfur burps are generally harmless, you should contact your GP or NHS 111 if you experience persistent or severe episodes, especially when accompanied by concerning symptoms such as severe or worsening abdominal pain, persistent vomiting, unintentional weight loss, black or bloody stools, fever, or signs of dehydration. Understanding the underlying cause is essential for appropriate management, particularly when sulfur burps emerge after starting new medications.

Does Rybelsus Cause Sulfur Burps?

Rybelsus (semaglutide) is an oral glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for the treatment of type 2 diabetes mellitus. Sulfur burps are not explicitly listed as an adverse reaction in the Summary of Product Characteristics (SmPC). However, there is a plausible connection between Rybelsus and this symptom based on the drug's mechanism of action and known gastrointestinal side effects.

According to the SmPC, the most frequently reported adverse effects of Rybelsus include:

• Nausea (frequency varies by dose, commonly reported)

• Diarrhoea

• Vomiting

• Abdominal pain

• Decreased appetite

• Constipation

• Dyspepsia (indigestion)

These gastrointestinal symptoms are typically most pronounced during treatment initiation and dose escalation, often diminishing over time as the body adjusts to the medication. The occurrence of sulfur burps in patients taking Rybelsus may relate to the drug's effect on gastric emptying rather than a direct chemical interaction, though this is based on observational reports rather than clinical trial data.

Patient reports suggest that some individuals taking GLP-1 receptor agonists, including Rybelsus, do experience sulfur burps. However, there is no official epidemiological data quantifying this specific symptom.

If you develop persistent sulfur burps after starting Rybelsus, particularly if accompanied by severe nausea, vomiting, or abdominal pain, contact your GP or diabetes specialist nurse. Importantly, if you experience severe, persistent abdominal pain (which may radiate to your back) with or without vomiting, stop taking Rybelsus and seek urgent medical attention, as this could indicate pancreatitis. Similarly, seek prompt medical advice for right upper abdominal pain, fever or jaundice (possible gallbladder disease), or signs of dehydration if experiencing vomiting or diarrhoea.

Do not discontinue Rybelsus without medical guidance, as this may affect your diabetes control. Patients can report suspected side effects via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

How to Manage Sulfur Burps While Taking Rybelsus

Managing sulfur burps whilst continuing Rybelsus treatment involves a combination of dietary modifications, lifestyle adjustments, and, when necessary, symptomatic relief measures. These strategies aim to reduce hydrogen sulfide production and improve overall digestive comfort without compromising diabetes management.

Dietary modifications form the cornerstone of management:

• Reduce sulfur-rich foods temporarily, including red meat, eggs, dairy products, garlic, onions, and cruciferous vegetables

• Eat smaller, more frequent meals rather than large portions, which can overwhelm digestive capacity

• Chew food thoroughly and eat slowly to reduce swallowed air and aid digestion

• Avoid carbonated beverages, which introduce additional gas into the digestive system

• Limit high-fat foods, as these delay gastric emptying further

• Stay well-hydrated with water throughout the day

Lifestyle adjustments can also prove beneficial. Taking Rybelsus correctly—on an empty stomach with no more than 120 mL of water, waiting at least 30 minutes before eating, drinking, or taking any other oral medicines—optimises absorption and may reduce gastrointestinal side effects. Gentle physical activity, such as a short walk after meals, can promote gastric emptying and reduce gas accumulation.

Some patients find relief with over-the-counter remedies, though these should be discussed with a healthcare professional:

• Simeticone-based anti-foaming products may help disperse gas bubbles (discuss with a pharmacist to avoid interactions)

• Ginger may soothe digestive discomfort (use with caution if taking anticoagulants)

• Peppermint tea may help some people but can worsen reflux in others

• Probiotics might help rebalance gut bacteria, though evidence is limited

If you experience vomiting or diarrhoea, maintain adequate fluid intake to prevent dehydration. If you cannot keep fluids down or symptoms persist, contact your healthcare provider promptly.

If sulfur burps persist despite these measures, or if they significantly impact quality of life, consult your prescriber. Dose adjustment, temporary dose reduction, or additional investigations (such as testing for H. pylori infection or SIBO) may be appropriate. Your healthcare team can provide personalised advice whilst ensuring your diabetes remains well-controlled.

Why Rybelsus May Lead to Digestive Side Effects

Understanding why Rybelsus causes digestive side effects requires knowledge of its pharmacological mechanism. Semaglutide, the active ingredient in Rybelsus, mimics the action of naturally occurring GLP-1, a hormone released by the intestine in response to food intake. This mechanism, whilst highly effective for glycaemic control, directly impacts gastrointestinal function.

GLP-1 receptor agonists exert several effects on the digestive system:

• Delayed gastric emptying: Semaglutide slows the rate at which food moves from the stomach into the small intestine. This prolongs the feeling of fullness (satiety) and helps control post-meal blood glucose levels. However, when food remains in the digestive tract longer, this may contribute to increased gas production, potentially including hydrogen sulfide.

• Altered gut motility: Changes in intestinal movement patterns can affect how efficiently food and gas transit through the digestive tract.

• Central nervous system effects: GLP-1 receptors in the brain influence appetite and nausea perception, contributing to the commonly reported nausea.

• Impact on concomitant medications: The delayed gastric emptying may affect the absorption of other oral medicines taken around the same time.

The dose-dependent nature of these effects explains why gastrointestinal symptoms are most prominent during treatment initiation and dose escalation. According to the Rybelsus SmPC, the recommended dosing is to start with 3 mg once daily for 30 days, then increase to 7 mg once daily. After at least 30 days on the 7 mg dose, it can be increased to 14 mg once daily if additional glycaemic control is needed.

Most patients experience improvement in gastrointestinal symptoms within 4–8 weeks as physiological adaptation occurs. The benefits of Rybelsus for diabetes management, as demonstrated in clinical trials, generally outweigh temporary digestive discomfort for most patients. Rybelsus has demonstrated cardiovascular safety in clinical trials, though it's worth noting that cardiovascular risk reduction is an established benefit for some injectable GLP-1 receptor agonists rather than an approved claim for oral semaglutide specifically.

Individualised assessment by your healthcare team ensures that treatment remains appropriate and tolerable for your specific circumstances.

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