Rybelsus (semaglutide) is a GLP-1 receptor agonist licensed in the UK for managing type 2 diabetes mellitus. Whilst hair loss is not listed as a recognised side effect in the official Summary of Product Characteristics approved by the MHRA or EMA, some patients have reported experiencing hair thinning during treatment. When hair loss does occur, it is typically linked to indirect factors such as rapid weight loss, nutritional deficiencies, or underlying health conditions rather than a direct effect of the medication itself. This article examines the evidence surrounding Rybelsus and hair loss, explores potential contributing mechanisms, and provides guidance on when to seek medical advice.

Does Rybelsus Cause Hair Loss?

Hair loss is not listed as a recognised side effect in the official Summary of Product Characteristics (SmPC) for Rybelsus (semaglutide) as approved by the Medicines and Healthcare products Regulatory Agency (MHRA) or the European Medicines Agency (EMA). Clinical trials conducted during the drug's development did not identify alopecia or hair thinning as a direct adverse reaction to semaglutide when taken orally.

However, some patients taking Rybelsus have reported experiencing hair loss or thinning, leading to understandable concern. While isolated post-marketing reports exist, a causal link has not been established. When hair loss does occur in individuals using this medication, it is more likely related to indirect factors such as rapid weight loss, nutritional deficiencies, or underlying health conditions rather than a direct pharmacological effect of the drug itself.

Rybelsus is licensed for the management of type 2 diabetes mellitus and works by mimicking a naturally occurring hormone that regulates blood glucose levels. Whilst the medication is generally well-tolerated, any new or concerning symptoms—including changes to hair growth—should be discussed with your GP or diabetes specialist. They can help determine whether the hair loss is coincidental, related to lifestyle changes accompanying treatment, or requires further investigation.

This article provides an evidence-based overview of Rybelsus, its common side effects, potential indirect mechanisms that might contribute to hair changes, and guidance on when to seek medical advice.

Understanding Rybelsus and How It Works

Rybelsus contains the active ingredient semaglutide, which belongs to a class of medications known as glucagon-like peptide-1 (GLP-1) receptor agonists. It is the first GLP-1 agonist available in oral tablet form, offering an alternative to injectable formulations. Rybelsus is licensed in the UK for adults with type 2 diabetes to improve glycaemic control alongside diet and exercise.

Mechanism of action: Semaglutide works by mimicking the action of GLP-1, a hormone naturally released by the intestines in response to food intake. GLP-1 receptor agonists enhance insulin secretion from the pancreas in a glucose-dependent manner, meaning they stimulate insulin release only when blood glucose levels are elevated. This reduces the risk of hypoglycaemia (though this risk increases when used with insulin or sulfonylureas). Additionally, semaglutide suppresses glucagon secretion (a hormone that raises blood glucose), slows gastric emptying, and promotes satiety, which can lead to reduced calorie intake and weight loss.

The medication is initiated at 3 mg once daily for 30 days (for tolerability, not glycaemic control), then increased to 7 mg once daily; a further increase to 14 mg may be considered if needed. Rybelsus must be taken on an empty stomach with up to 120 ml of water, at least 30 minutes before eating, drinking, or taking other oral medicines. The tablet should be swallowed whole (not split, crushed or chewed). If a dose is missed, skip it and take the next dose the following day.

The delayed gastric emptying caused by Rybelsus can alter the absorption of some oral medicines, which may require monitoring when clinically relevant (e.g., levothyroxine).

Weight loss may occur during treatment with Rybelsus; the magnitude varies between individuals. It is important to note that Rybelsus is not licensed for weight management in the UK.

Common Side Effects of Rybelsus

Like all medications, Rybelsus can cause side effects, although not everyone will experience them. The most frequently reported adverse effects are gastrointestinal in nature and tend to be more pronounced during the initial weeks of treatment or following dose increases.

Very common side effects (affecting more than 1 in 10 people) include:

• Nausea – often the most troublesome symptom, particularly when starting treatment

• Diarrhoea – may be mild to moderate and usually improves over time

Common side effects (affecting up to 1 in 10 people) include:

• Vomiting

• Abdominal pain or discomfort

• Decreased appetite

• Dyspepsia (indigestion)

• Constipation

• Cholelithiasis (gallstones)

These gastrointestinal symptoms typically diminish as the body adjusts to the medication. Eating smaller, more frequent meals and avoiding high-fat foods may help manage these effects.

Significant gastrointestinal symptoms can lead to dehydration and potentially acute kidney injury. It's important to maintain adequate fluid intake and contact your healthcare provider if you're unable to keep fluids down.

Less common but important side effects include hypoglycaemia (particularly when used with insulin or sulfonylureas) and pancreatitis (inflammation of the pancreas). Patients should seek urgent medical attention if they experience severe, persistent abdominal pain that may radiate to the back, as this could indicate pancreatitis.

Diabetic retinopathy complications can occur, particularly in patients with pre-existing retinopathy, and appropriate monitoring is recommended.

Hypersensitivity reactions, including anaphylaxis and angioedema, have been reported but are uncommon.

Notably, hair loss is not listed among the recognised side effects in the Summary of Product Characteristics or patient information leaflets approved by UK regulatory authorities. Any hair changes reported by patients warrant individualised assessment to identify potential contributing factors.

If you experience any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or via the Yellow Card app.

Why Hair Loss May Occur During Rybelsus Treatment

Although hair loss is not a documented direct side effect of Rybelsus, several indirect mechanisms may explain why some patients experience hair thinning or shedding whilst taking this medication.

Rapid weight loss: Rybelsus can lead to weight reduction in many patients with type 2 diabetes. However, rapid or substantial weight loss—particularly when exceeding 0.5–1 kg per week—can trigger a condition called telogen effluvium. This is a form of temporary hair loss that occurs when a large number of hair follicles prematurely enter the resting (telogen) phase of the hair growth cycle. Hair shedding typically becomes noticeable 2–3 months after the triggering event and is usually reversible once weight stabilises.

Nutritional deficiencies: The appetite suppression and reduced calorie intake associated with Rybelsus may inadvertently lead to inadequate nutrition if dietary quality is not maintained. Deficiencies in protein, iron, zinc, and vitamins (particularly B vitamins and vitamin D) can all contribute to hair thinning. Patients experiencing significant weight loss should ensure they consume a balanced diet rich in essential nutrients. Any supplements, including biotin, should be discussed with a healthcare professional, as some can interfere with laboratory tests (e.g., thyroid and troponin assays).

Metabolic and hormonal changes: Substantial weight loss and improved glycaemic control can alter hormone levels, including thyroid hormones, sex hormones, and cortisol. These changes, whilst often beneficial overall, may temporarily affect hair growth cycles.

Underlying health conditions: Type 2 diabetes itself, along with commonly associated conditions such as thyroid disorders, polycystic ovary syndrome (PCOS), or iron deficiency anaemia, can cause hair loss independent of medication use.

Stress and lifestyle factors: Managing a chronic condition, adjusting to new medications, and implementing lifestyle changes can be stressful, and psychological stress is a recognised contributor to telogen effluvium.

It is important to emphasise that if hair loss occurs during Rybelsus treatment, it is most likely attributable to these indirect factors rather than a direct toxic effect of semaglutide on hair follicles.

When to Speak to Your GP About Hair Loss

If you notice increased hair shedding or thinning whilst taking Rybelsus, it is advisable to discuss this with your GP or diabetes specialist, particularly if the hair loss is significant, persistent, or causing distress.

You should arrange a routine appointment if:

• Hair loss is gradual and has been ongoing for several weeks

• You have lost a significant amount of weight rapidly (more than 0.5–1 kg per week)

• You are concerned about the adequacy of your diet or suspect nutritional deficiencies

• You have other symptoms such as fatigue, cold intolerance, or changes in skin or nails that might suggest thyroid dysfunction or anaemia

Seek more urgent advice if:

• Hair loss is sudden, severe, or occurs in patches (which may indicate alopecia areata or other dermatological conditions)

• You develop additional concerning symptoms such as unexplained bruising, severe fatigue, or signs of infection

• You experience other new or worsening side effects from Rybelsus, particularly severe gastrointestinal symptoms that may lead to dehydration

What your GP may do:

Your doctor will take a detailed history, including the timeline of hair loss relative to starting Rybelsus, the rate of weight loss, dietary habits, and any other symptoms. They may perform a physical examination and arrange blood tests to assess:

• Full blood count (to check for anaemia)

• Ferritin (iron stores)

• Thyroid function tests (TSH, free T4)

• Vitamin B12 and folate levels

• HbA1c (to assess diabetes control)

• Urea and electrolytes (if there have been significant gastrointestinal symptoms or concerns about dehydration)

Depending on findings, your GP may recommend dietary modifications, nutritional supplementation, or referral to a dietitian. Referral to dermatology may be considered if there is patchy hair loss, scarring, diagnostic uncertainty, or persistent/severe shedding despite correction of reversible causes. In most cases, hair loss related to weight loss or nutritional factors is temporary and reversible with appropriate management.

Do not stop taking Rybelsus without medical advice, as this could adversely affect your diabetes control. Open communication with your healthcare team ensures any concerns are addressed whilst maintaining optimal management of your condition.

Frequently Asked Questions