Rybelsus and Sun Exposure: Safety Guidance for Diabetes Patients

Rybelsus (semaglutide) is an oral GLP-1 receptor agonist licensed in the UK for treating type 2 diabetes mellitus in adults. Whilst photosensitivity is not a recognised side effect of Rybelsus, patients with diabetes should maintain good sun safety practices year-round. This article examines the relationship between Rybelsus and sun exposure, explores why sun protection remains important for people with diabetes, and provides guidance on recognising side effects and knowing when to seek medical advice whilst taking this medication.

What Is Rybelsus and How Does It Work?

Rybelsus (semaglutide) is an oral medication licensed in the UK for the treatment of type 2 diabetes mellitus in adults. It belongs to a class of medicines called glucagon-like peptide-1 (GLP-1) receptor agonists, which work by mimicking the action of a naturally occurring hormone that helps regulate blood sugar levels.

The mechanism of action involves several complementary effects. Rybelsus stimulates insulin secretion from the pancreas when blood glucose levels are elevated, whilst simultaneously suppressing the release of glucagon, a hormone that raises blood sugar. Additionally, it slows gastric emptying, which helps reduce post-meal glucose spikes, and may promote a feeling of fullness that can support weight management efforts.

Rybelsus is typically prescribed when diet and exercise alone, or in combination with other diabetes medications such as metformin, have not achieved adequate glycaemic control. The medication is taken once daily on an empty stomach with no more than 120ml of water, at least 30 minutes before the first food, drink, or other oral medications of the day. The tablet must be swallowed whole and not split, crushed or chewed. This specific timing and administration is crucial for optimal absorption.

Treatment is initiated at 3mg once daily for 30 days, then increased to 7mg once daily. If additional glycaemic control is needed after at least 30 days on the 7mg dose, it may be increased to 14mg once daily. If a dose is missed, the patient should skip that dose and take the next dose the following day.

Rybelsus is not indicated for type 1 diabetes or for the treatment of diabetic ketoacidosis.

The National Institute for Health and Care Excellence (NICE) provides guidance on the use of GLP-1 receptor agonists, including semaglutide, as part of a comprehensive diabetes management strategy. Treatment should be initiated and monitored by healthcare professionals experienced in diabetes care, with regular review of glycaemic control and tolerability.

Sun Safety While Taking Rybelsus

Photosensitivity reactions are not listed in the Rybelsus Summary of Product Characteristics (SmPC) or Patient Information Leaflet (PIL). Current evidence from clinical trials and post-marketing surveillance has not identified sun exposure as a specific concern for patients taking this GLP-1 receptor agonist.

However, individuals with diabetes—regardless of their medication regimen—should maintain good sun safety practices for several important reasons. Diabetes can affect skin health in various ways, potentially making the skin more vulnerable to damage and slower to heal. Prolonged sun exposure can lead to dehydration, which may affect blood glucose control and increase the risk of diabetic complications.

General sun safety recommendations for all patients with diabetes include:

• Apply broad-spectrum sunscreen with SPF 30 or higher, reapplying every two hours and after swimming or sweating

• Wear protective clothing, including wide-brimmed hats and UV-protective sunglasses

• Seek shade during peak sun intensity hours (11am–3pm in the UK)

• Stay well-hydrated, as dehydration can affect blood glucose levels

• Monitor blood sugar more frequently during hot weather, as heat can influence glucose metabolism (and insulin absorption in those using insulin therapy)

If you notice any unusual skin changes, increased sensitivity, or unexpected reactions whilst taking Rybelsus, these should be discussed with your GP or diabetes specialist and reported through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk). Whilst not directly related to sun exposure, maintaining overall skin health is an important aspect of diabetes self-care.

Side Effects of Rybelsus to Monitor

Like all medications, Rybelsus can cause side effects, though not everyone experiences them. Understanding the most common and serious adverse effects helps patients recognise when medical attention may be needed.

Gastrointestinal side effects are the most frequently reported and typically occur during the initial weeks of treatment or following dose increases. These include:

• Nausea (very common, affecting more than 1 in 10 people)

• Vomiting and diarrhoea (common)

• Abdominal pain and decreased appetite (common)

• Constipation and indigestion (common)

These symptoms often improve as the body adjusts to the medication. Taking Rybelsus as directed—on an empty stomach with no more than 120ml of water—and eating smaller, more frequent meals may help minimise gastrointestinal discomfort. Severe or prolonged vomiting or diarrhoea can lead to dehydration and kidney problems; seek medical advice if these occur.

Hypoglycaemia (low blood sugar) can occur, particularly when Rybelsus is used in combination with other diabetes medications such as sulphonylureas or insulin. When starting Rybelsus, a reduction in the dose of these medications may be needed to reduce the risk of hypoglycaemia. Symptoms include trembling, sweating, confusion, palpitations, and hunger. Patients should be educated on recognising and treating hypoglycaemia promptly.

Serious but rare side effects require immediate medical attention:

• Pancreatitis: Severe, persistent abdominal pain that may radiate to the back, often accompanied by nausea and vomiting. If pancreatitis is suspected, stop taking Rybelsus and seek urgent medical attention.

• Diabetic retinopathy complications: Sudden changes in vision. Rapid improvement in blood glucose control may temporarily worsen diabetic retinopathy, particularly in patients with pre-existing retinopathy or on insulin therapy. Regular eye examinations are recommended.

• Severe allergic reactions: Difficulty breathing, swelling of the face or throat, severe rash

• Gallbladder problems: Cholelithiasis (gallstones) or cholecystitis (gallbladder inflammation) can occur, causing severe upper abdominal pain, fever, or yellowing of skin or eyes

Patients taking levothyroxine should be aware that Rybelsus may increase thyroid hormone exposure; thyroid function tests may need monitoring. Those on warfarin should consider more frequent INR monitoring when starting Rybelsus.

The Medicines and Healthcare products Regulatory Agency (MHRA) monitors the safety of all medications in the UK. Patients and healthcare professionals are encouraged to report suspected adverse reactions through the Yellow Card Scheme at yellowcard.mhra.gov.uk.

When to Seek Medical Advice

Knowing when to contact your healthcare provider is essential for safe and effective use of Rybelsus. Routine follow-up with your GP or diabetes specialist should occur regularly to monitor glycaemic control, assess tolerability, and adjust treatment as needed. NICE guidance recommends reviewing GLP-1 receptor agonist therapy at six months to evaluate effectiveness, with continuation criteria typically including a reduction in HbA1c and weight loss.

Contact your GP, diabetes nurse or NHS 111 if you experience:

• Persistent nausea, vomiting, or diarrhoea that interferes with eating, drinking, or taking medications

• Inability to keep fluids down, which could lead to dehydration and kidney problems

• Unexplained weight loss beyond what is expected with diabetes management

• Recurrent episodes of hypoglycaemia

• Any new or worsening symptoms that concern you

• Difficulty adhering to the medication schedule or uncertainty about proper administration

If you miss a dose of Rybelsus, skip that dose and take the next dose the following day. Do not take a double dose to make up for a missed dose.

Seek urgent medical attention (call 999 or go to A&E) if you develop:

• Severe abdominal pain that is persistent and does not resolve, particularly if accompanied by vomiting—this could indicate pancreatitis

• Signs of severe dehydration: extreme thirst, very dark urine, dizziness, confusion, or reduced urine output

• Symptoms of a severe allergic reaction: difficulty breathing, swelling of the face, lips, tongue, or throat, or severe skin reactions

• Sudden vision changes or loss of vision

• Symptoms of gallbladder disease: severe upper right abdominal pain, fever, jaundice (yellowing of skin or eyes)

Important information before and during treatment:

• Rybelsus should not be used during pregnancy or breastfeeding

• If planning pregnancy, discontinue Rybelsus at least 2 months before attempting conception

• Inform your healthcare provider about any history of pancreatitis, thyroid disease, or diabetic retinopathy

• If you take levothyroxine, your thyroid function may need monitoring

• If you take warfarin, more frequent INR monitoring may be needed when starting Rybelsus

• Report all other medications you are taking, including over-the-counter medicines and supplements

Maintaining open communication with your diabetes care team ensures that any concerns are addressed promptly and that your treatment remains optimally tailored to your individual needs.

Frequently Asked Questions