How old and new strengths match

MHRA's December 2025 safety communication pairs the formulations like this. The old 3 mg starting tablet matches the new 1.5 mg starting tablet. Old 7 mg matches new 4 mg. Old 14 mg matches new 9 mg. These pairings apply to this Rybelsus formulation change only. Do not treat them as a general rule for halving a semaglutide dose.

Why the printed number fell

The dose you swallow and the amount reaching your bloodstream are different quantities. A new formulation can change how well a medicine is absorbed. So the milligrams on the box do not tell you whether treatment is now stronger or weaker. Compare against the recognised matching strength, and confirm it with your dispensing pharmacist and your prescription.

Take one tablet a day

Take one Rybelsus tablet each day. Do not combine smaller tablets to make a bigger dose, switch between formulations to aim for an average, or split a tablet. Each of these changes absorption unpredictably and does not match the approved product. If your pharmacy cannot supply your prescribed strength, the pharmacist and prescriber should agree a suitable alternative.

Check a new pack before the first dose

If a pack looks different, check the brand, strength, formulation and dispensing label before you take a tablet. Ask whether this is a like-for-like formulation swap or a real change to your treatment. Keep a photo or note of your previous pack for the conversation. Hand unwanted or old tablets back to a pharmacy. Mixed strengths in a kitchen drawer lead to mistakes.

The Rybelsus table does not apply to Wegovy

Wegovy tablets come in strengths a Rybelsus user may recognise. Similar numbers do not make the products interchangeable, and a diabetes prescription cannot be stretched into a weight-loss schedule. Wegovy has its own licensed instructions, patient group and maintenance dose. Any move between brands needs a clear prescription and a plan to review benefits and side effects.

If you took the wrong strength

Contact a pharmacist, your prescriber or NHS 111 straight away. Give the exact product, strength, number of tablets and time taken. Do not make yourself sick or take another tablet to "balance" the dose. Call 999 if someone faints, struggles to breathe or is unconscious. A written record of the error helps the clinical team assess the risk and helps the pharmacy stop it happening again.

Make the change visible to every service

If a hospital letter or repeat prescription system still shows the old strength, ask for the record to be updated once the formulation change is confirmed. A mismatch can look like a dose cut or lead to a double supply. Keep the pharmacist's explanation with your medication list, especially when you travel or visit urgent care. Never peel the dispensing label off a pack to save space. The full product details help another professional sort out prescriptions that seem to conflict.

Sources

Your own medicine leaflet and prescriber come first. A source from another country does not mean the same rule applies in the UK.

  1. MHRA: Rybelsus formulation transition gov.uk
  2. Rybelsus: UK prescribing information medicines.org.uk
  3. Wegovy tablets: UK prescribing information medicines.org.uk

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