Living on GLP-1: alcohol, travel, missed doses

Can I drink alcohol?

There's no interaction warning on the label.

Based on the labelling for semaglutide, tirzepatide and liraglutide, none of them mentions alcohol, including in the interactions section. So anything we tell you here is clinical judgement rather than something we can point to in a package insert.

Alcohol is calories, and it tends to arrive alongside food that isn't part of the plan. It can worsen nausea, particularly in the days after a dose increase. And if you're also on insulin or a sulfonylurea for diabetes, alcohol raises the risk of hypoglycaemia, which is a different and more serious problem.

A glass of wine at a dinner isn't something we'd tell you to refuse, but four beers on the night you've just stepped up your dose is just asking for a bad evening.

Missed a dose?

Depends what you're on, and it's worth knowing your own answer before it happens.

For a weekly injection, there's a catch-up window. The instructions depend on the specific product and formulation. For example, semaglutide can generally be taken within five days of the missed dose, and if more than five days have gone, skip it and go back to your normal day. For tirzepatide, the missed dose should generally be taken within four days; otherwise, skip it and resume on the usual day.

If you've missed two or more consecutive weekly doses, don't just resume where you left off. Your dose may need to restart lower and step back up, so message us before your next one.

For a daily tablet, there's no catch-up. Skip the missed one and take the next one the following day.

Labelling differs between regulators, so follow what's on the product you were actually dispensed, and ask us if it isn't clear.

Flying with an injection

In your hand luggage, with a copy of your prescription or a letter from us, and never in checked luggage.

Two reasons: temperatures down there are not reliably controlled and can drop below freezing, which ruins the pen, and checked bags go missing. Keep it with you.

Airport security is used to injectable medicines. A pen, needles, and a sharps container in a clear bag with documentation is routine, and it's worth carrying the letter even if nobody asks for it.

If you're crossing time zones and your dose day moves, keep the same day of the week rather than the same clock time. A few hours either way makes no difference to a weekly injection.

Does it need refrigeration?

Before you open it, yes. After that you have more room than you think.

Unopened pens go in the fridge between 2 and 8 degrees, away from the cooling element, and never in the freezer. If it's been frozen, don't use it.

Once in use, United Kingdom labelling allows a semaglutide pen to be kept for up to six weeks below 30 degrees or in the fridge. For a tirzepatide multi-dose pen, it's up to 30 days unrefrigerated. United States labelling gives shorter windows for both, so check what came with yours.

For a week in Bali, a cool bag and a hotel fridge cover it. For a month somewhere without reliable refrigeration, talk to us before you go.

Hawker food, small appetite

This is the most Singaporean question we get, and the answer isn't to stop eating out.

Your appetite will be genuinely smaller, so the practical problem becomes getting enough protein into a much smaller volume of food. That means going for the fish, the chicken, the egg, the tofu, the tau huay, and treating the rice and noodles as the part you don't need to finish.

Ordering half portions, sharing, or taking half away is normal.

The thing we'd watch is a work dinner where you can't control the pace. Eating slowly and stopping when you're full matters more on this treatment than it used to, because the fullness signal arrives earlier and ignoring it comes with consequences you'll feel.

Can I fast for bloods?

Yes, and you should, when we ask you to.

A fasting blood test on this treatment works the same as it did before. Water is fine, and you take your weekly injection on its normal day regardless.

If you're on the daily tablet, that already requires a fasting stomach, so a morning blood test usually slots in without changing anything. Tell the phlebotomist what you're taking anyway.

If you need surgery

Tell the anaesthetist, well before the day, and tell them what you're on by name of the active ingredient.

This matters because these medicines slow how fast the stomach empties. Cases of pulmonary aspiration have been reported in patients on GLP-1 receptor agonists having general anaesthesia or deep sedation, and both the UK and US labels now mention it.

What we won't do here is tell you to stop your medicine a week before a procedure. Guidance on that has been moving. The appropriate approach depends on the medication, procedure, aspiration risk and individual patient factors.

Discuss it with your anaesthetist and surgical team well before the procedure.

Ramadan and other fasting

Worth planning rather than improvising, and worth a conversation before the month starts.

A weekly injection doesn't need to move for a daily fast. The daily tablet is harder. Its fasting and post-dose timing requirements depend on the product. Those requirements have to fit around suhoor rather than your usual morning.

The bigger issue is fluid. Reduced appetite plus a long fast and a warm climate is a dehydration risk, and dehydration is what turns a manageable side effect into a bad day.

Come and see us before Ramadan rather than during it, and we'll work out the timing together.

Do I tell my insurer?

Check your policy, and if it asks, disclose now rather than at claim time.

Most policies ask you to disclose prescription medicines and any change in your health at renewal or when making a claim. Not disclosing something you were asked about is what causes problems, rather than the treatment itself.

We can't tell you what your policy says. What we'd suggest is asking your insurer in writing what they need, and keep the reply.

The bottom line

The clinical questions get settled at your consult. The practical ones are worth asking before they arrive, rather than after.