Semaglutide

What is semaglutide?

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist. GLP-1 is a hormone released by the gut after eating. Semaglutide-containing products have distinct authorised indications, formulations and dosing instructions.

This page explains the effects on appetite, glucose and digestion. It does not establish semaglutide as a treatment for digestive disorders.

Effects on digestion and metabolism

• Gastric emptying: semaglutide delays stomach emptying, particularly in the early post-meal phase. This can influence absorption of other oral medicines.
• Appetite: it reduces hunger and energy intake and increases satiety.
• Glucose: it increases insulin secretion and reduces glucagon in a glucose-dependent manner. This does not eliminate hypoglycaemia, especially with insulin or sulphonylureas.
• Digestive adverse effects: nausea, diarrhoea and constipation can occur. Claims that it treats diarrhoeal urgency, repairs the gut barrier or reduces intestinal inflammation are not established indications.

Who is it for?

The product matters:

For Ozempic, use alone is indicated when metformin is inappropriate because of intolerance or contraindications; it can also be added to other diabetes medicines.

For adult injectable Wegovy, the initial BMI criteria are ≥30, or ≥27 to <30 with at least one weight-related comorbidity. Its separate adolescent indication starts at 12 years with obesity and weight above 60 kg; adult criteria and higher adult doses must not be transferred to adolescents.

Rybelsus is an oral semaglutide product for type 2 diabetes. The current Wegovy information also contains an oral formulation. Oral and injectable instructions are different: this article does not supply an oral dosing or switching regimen. Product authorisation does not prove availability in Spain.

Dosage: Ozempic injection example

This table applies only to Ozempic; it is not a universal semaglutide schedule.

The 0.25 mg dose is not maintenance. Escalation requires the prescriber’s direction. Inject into the abdomen, thigh or upper arm, with or without food. A missed Ozempic dose can be taken within 5 days; later, skip it and resume the usual day. Changing the weekly day requires more than 72 hours between doses.

Wegovy injection has a different escalation schedule to 2.4 mg weekly. Selected adults with an initial BMI ≥30 may increase to 7.2 mg weekly after at least 4 weeks at 2.4 mg; this is not an Ozempic or adolescent dose. Do not interchange pens or change a regimen yourself.

Side effects

Frequency depends on the product and population. For Ozempic, nausea and diarrhoea are very common (at least 1 in 10); vomiting, constipation, abdominal pain, bloating, indigestion and reflux are common (at least 1 in 100 but fewer than 1 in 10). Wegovy’s frequency table differs; do not transfer this classification to every semaglutide formulation.

Other reported effects include headache, fatigue and injection-site reactions. Hypoglycaemia is particularly relevant with insulin or sulphonylureas.

Symptoms requiring medical attention

• Severe, persistent abdominal pain, sometimes spreading to the back: stop semaglutide and seek urgent care for possible pancreatitis. If confirmed, do not restart. Previous pancreatitis requires caution, not an automatic EU contraindication.
• Sudden loss of vision: obtain urgent eye assessment. Treatment must stop if non-arteritic anterior ischaemic optic neuropathy (NAION) is confirmed.
• Breathing difficulty or facial/throat swelling: seek emergency care for possible severe allergy.
• Pain with fever or jaundice: seek assessment for gallbladder disease.
• Severe constipation with pain, bloating or vomiting: obtain urgent assessment for possible intestinal obstruction.
• Persistent vomiting or diarrhoea: seek advice, particularly if unable to drink, because dehydration can worsen kidney function.

Important safety information

The EU contraindication for Ozempic and injectable Wegovy is hypersensitivity to semaglutide or an excipient. US thyroid-tumour contraindications must not be recast as the EU list. Share all personal and family medical history.

Do not use during pregnancy or breastfeeding. Stop at least 2 months before planned pregnancy, with a clinical plan for diabetes treatment where relevant. Notify the prescriber if pregnancy occurs.

Tell the doctor about pancreatitis, gallbladder disease, retinopathy, gastroparesis, kidney or liver disease and eating disorders. Use of semaglutide is not recommended in patients with severe gastroparesis. Retinopathy needs monitoring, particularly with insulin and rapid glucose improvement. Uncontrolled or potentially unstable retinopathy is a reason not to use Ozempic 2 mg or Wegovy under their respective warnings.

Renal and hepatic restrictions are product-specific: Ozempic does not require renal dose adjustment, but end-stage experience is limited and severe hepatic impairment requires caution. Wegovy is not recommended with severe renal or severe hepatic impairment. Neither product is recommended in NYHA class IV heart failure. They do not replace insulin or treat diabetic ketoacidosis; do not stop insulin yourself.

Discuss all medicines. Insulin or sulphonylurea adjustment must be clinician-led. Starting semaglutide with warfarin or other coumarins requires more frequent INR monitoring. The studied oral contraceptives did not show a clinically relevant reduction in exposure; delayed gastric emptying does not itself establish loss of contraceptive efficacy. Other oral drugs requiring rapid absorption need assessment. Do not combine GLP-1 products without a prescribing assessment; Wegovy should not be combined with other GLP-1 receptor agonists.

Tell the anaesthesia team before general anaesthesia or deep sedation because delayed stomach emptying can increase aspiration risk.

Accessing an independent assessment

Semaglutide medicines require a prescription. Prescrivia is a technology intermediary: it does not prescribe, employ doctors or sell medicines.

1. Provide your medical history, medication list and treatment goals.
2. An independent doctor assesses whether any product is appropriate.
3. If a prescription is issued, a licensed pharmacy assesses dispensing and delivery under applicable rules and availability.

No prescription, stock or outcome is guaranteed. Diet and physical activity remain part of care.

In Spain, distance sale of prescription medicines is prohibited under Article 3.5 of Royal Legislative Decree 1/2015. An online assessment does not remove this restriction. Dispensing and access depend on the exact product and applicable national rules.

Sources

• EMA: Ozempic product information, sections 4.1–4.8 and 5.1.
• EMA: Wegovy product information, formulation-specific sections 4.1–4.8.

This is selected patient information, not the complete leaflet or individual medical advice.