Nausea is common. Back pain isn't.

Nausea, vomiting, diarrhoea, constipation, reduced appetite, reflux, burping and tiredness are the commonly reported ones. They're typically worst when starting and after each dose increase, and often ease over the following weeks — which is why doses go up gradually. Common doesn't mean you must endure it, though: effects bad enough to stop you eating, drinking or working are worth a call, and prescribers can often adjust the plan.

Severe or persistent abdominal pain, especially spreading to the back; pain under the right ribs with fever, yellowing skin or eyes, or pale stools; being unable to keep fluids down or signs of dehydration; severe constipation with swelling and vomiting; and any swelling of the face, lips or throat or difficulty breathing. These are the patterns associated with pancreatitis, gallbladder problems, kidney strain and allergic reactions, and they need assessment rather than reassurance.

These medicines slow how quickly the stomach empties, so food sits there longer and fullness arrives sooner. Eating to your old sense of fullness now overfills a stomach that's emptying slowly — the commonest trigger for nausea. Stopping at the first sign of fullness, eating slowly, and going easy on fatty or fried food helps most people. Many notice it's strongest in the day or two after injecting.

Any procedure or anaesthetic team, in advance — a slowly emptying stomach matters for sedation, and guidance on what to do beforehand differs between teams, so let them instruct you. Ask about contraception if you take the pill, since at least one medicine in this class has been noted to reduce its reliability. Discuss pregnancy plans well ahead. And raise any personal or family history of thyroid cancer if it hasn't been discussed.

Yes, and it's worth raising without any embarrassment. Counterfeit versions have been found, and dosing errors with unregulated or compounded products have led to hospital admissions. A product obtained without a prescription from a regulated pharmacy means nobody has checked it's suitable for you or that it's what the label says. A pharmacist or doctor will discuss it without judgement.