GLP-1 injection sites, storage and flying with a pen from Changi

Singapore permits up to three months' supply of your own prescribed medicine when you travel, with documentation (HSA), and Eli Lilly and Singapore Airlines say to carry it in the cabin rather than in checked luggage (Lilly Canada, Singapore Airlines). The pen is stored refrigerated before first use, the after-first-use allowance differs for every pen type, and the injection goes in the abdomen or thigh.

The upper arm is treated differently by each medicine's label, and the labels set the limits for moving a weekly dose when you cross time zones. One number in the current labelling is genuinely contradictory, and this article says so rather than picking a side.

In Singapore, tirzepatide is registered as Mounjaro, and semaglutide injection as Wegovy for weight management and as Ozempic for type 2 diabetes. The figures in this article are given by molecule, as the trials and product labels report them. Whichever medicine is prescribed, GetLean plans the exit from the first consultation. Coming off GLP-1 in Singapore: what happens and how to plan sets out how.

Instructions for Use: the device leaflet packed with the pen itself, separate from the prescribing information. It is written for the exact presentation you were dispensed, which is why it beats any general article, including this one.

Where the labels say the injection goes

Both medicines are injected under the skin, and the site lists are close but not the same.

The US semaglutide label names the abdomen, thigh or upper arm, instructs at least 2 inches (5 cm) of clearance from the navel, and says sites are rotated with each dose — you may use the same body area each week, but not the same spot as the last injection (label).

Tirzepatide's US label diverges on one point that matters. It designates the thigh and stomach for self-injection, at least 2 inches from the navel, and states the back of the upper arm for administration by another person rather than for injecting yourself (label). Rotation is weekly.

So "upper arm" is not a class-wide instruction: one document has it as a self-injection site, the other as something a second person does. The leaflet in your own box is the reference, not a general guide.

Storage before first use

Both medicines are refrigerated at 2°C to 8°C (36°F to 46°F) before first use, and this is the one figure that is consistent everywhere (semaglutide, tirzepatide).

The semaglutide label adds that the pen is not stored in the freezer or directly against the refrigerator's cooling element (label). For the multi-dose tirzepatide presentation there is an additional route: unopened, it can be kept refrigerated until the printed expiry date, or at room temperature up to 30°C (86°F) for 30 days before opening (label).

After first use, the day-limit depends on which pen

This is the part most often got wrong, because people repeat a number from a different pen.

Four presentations, four different figures in the US labelling:

• Single-dose semaglutide pen or syringe — may be kept from 8°C to 30°C (46°F to 86°F) for up to 28 days, and is thrown away if it has been frozen, exposed to light or to temperatures above 30°C (86°F), or out of the refrigerator for 28 days or longer (label).
• Multi-dose semaglutide pen — 56 days after first use, with the same "discard if exposed above 30°C (86°F)" trigger (label).
• Single-dose tirzepatide pen or vial — may be kept unrefrigerated at temperatures not to exceed 30°C (86°F) for up to a total of 21 days, then discarded even if medicine remains (label).
• Multi-dose tirzepatide vial or pen — discarded at whichever comes first of 30 days at room temperature, 30 days after first use, or the fourth weekly dose, again even with medicine left in it (label).

Note also that the tirzepatide phrasing is a ceiling — "not to exceed 30°C" — while the single-dose semaglutide phrasing is a two-sided range, 8°C to 30°C. One does not convert into the other.

The European labels differ on the multi-dose pens. For the tirzepatide pen, the European label states its unrefrigerated allowance before first use only as up to 72 hours below 30°C, for getting the pen to the patient, and keeps 30 days after first use (EU label); the US label's 30 days unopened at room temperature is not in it. For the semaglutide pen, the European label gives 6 weeks after first use, below 30°C or in a refrigerator, and up to 48 hours below 30°C for getting it to the patient (EU label). The 21-day figure belongs only to the single-dose tirzepatide pen and vial, in both regions (EU label, US label). The leaflet in your own box is the one that applies to your pen.

The room-temperature figure the label contradicts itself on

For the multi-dose semaglutide pen, the current US label states two different after-first-use room-temperature ranges in two different places within the same document (label).

The 56-day duration is stated consistently, and so is the instruction to discard the pen if it has been above 30°C (86°F). The temperature band for ordinary day-to-day storage is where the document disagrees with itself, and that has not been resolved.

So this article gives no number for it. Read the leaflet that came with your own pen and put the question to your pharmacist, who can look at the exact presentation in front of you. Where a document contradicts itself, the answer belongs to a person with your pen in view.

Travelling: what Singapore allows you to bring

The Health Sciences Authority sets a general rule for personal medication: up to three months' supply where no approval is needed and the medicine is not prohibited, carrying a copy of a valid prescription or doctor's letter, with each medication in its original container or packaging and labelled by the dispensing pharmacy with the patient name, medication name and quantity (HSA).

Two things follow. The allowance is for your own prescribed medicine, not for carrying supply for someone else. And the "original packaging" requirement is about authenticity — decanting pens into an unlabelled cool bag defeats the documentation, whatever it does for temperature.

On temperature itself, there is a gap worth naming. That page covers quantity, documentation and labelling, and carries nothing about cold-chain storage, refrigeration, insulated carriers or ice packs (HSA). No Singapore government source located tells a traveller how to keep a pen cold. Ask your pharmacist, and read the storage section of your own leaflet before you pack.

Transit, customs and more than three months

More than three months' supply. HSA's page says imports of quantities exceeding three months' supply are not allowed, and that the medicine must be lawfully prescribed to you in your country of residence, with a copy of the prescription or doctor's letter from that country (HSA). For a longer stay, HSA's alternative is to consult a doctor registered with the Singapore Medical Council once in Singapore, to obtain the medication or a suitable substitute locally.

Transit through Singapore. HSA's transit rule is written for medicines containing controlled substances: no approval is needed to carry them if you only transit without clearing immigration, staying in the transit zone, or if you clear immigration without the medicines. Prohibited medicines cannot be brought in even in transit; HSA's prohibited list is substances in the Fourth Schedule to the Misuse of Drugs Regulations, medicines in chewing-gum form, cell, tissue and gene therapy products, and nicotine products obtained outside Singapore (HSA).

Declaring at customs. The rules sit on three pages. Singapore Customs says to use the Red Channel if you are carrying controlled, restricted or prohibited goods, and, if you are unsure, to approach a checking officer at the Red Channel (Singapore Customs). ICA lists medicines among the controlled goods for which HSA is the competent authority, and asks travellers who need a medicine that is only available on prescription in Singapore to carry a doctor's prescription confirming they need it (ICA). HSA says medicines it has approved do not need to be declared, as long as the approval and documents are kept ready for inspection (HSA). So carry the prescription or doctor's letter with the pen, and ask at the Red Channel if in doubt, as Customs advises.

Getting through the airport

Changi Airport lists medication accompanied by a doctor's letter among the exceptions to its powder-screening rule, and states that items may be exempted from the 100ml cap on liquids, aerosols and gels on presentation of a bona fide doctor's letter (Changi Airport). Cooling packs are not named anywhere on that page, so the letter is the thing doing the work — expect to explain what you are carrying.

Singapore Airlines is more specific about needles: a prescription or note from a registered physician is required to carry syringes or hypodermic needles on board, and medically necessary ones are exempt from the usual prohibitions where the passenger also has the prescription medication with a professionally printed label identifying the medical office, pharmacy or manufacturer. Medication is permitted in cabin baggage within a reasonable amount, with a physician's letter recommended (Singapore Airlines, baggage restrictions).

Other carriers set their own policies, so check the one you are flying. And if a trip runs longer than the after-first-use window for your pen, that is a scheduling question for your prescriber before you leave rather than an improvisation at the destination. We cover the related timing problem in what to do about a missed dose.

Why the pen goes in your cabin bag, not the hold

Eli Lilly's Canadian travel page for the multi-dose tirzepatide pen says to keep the pen with you when travelling and not to pack it in checked luggage, because luggage hold areas can have wide changes in temperature that may be too cold or too hot for the pen (Lilly Canada). Both US labels say not to use a pen that has been frozen (tirzepatide, semaglutide).

Singapore Airlines says the same from the carrier's side: medication should be kept in your hand luggage, not checked in, with a letter from your physician outlining your condition and medication (Singapore Airlines).

Lilly's page adds three points about security and the flight: airport X-ray screening is not known to affect the medicine, you can ask for the pen and supplies to be inspected by hand, and changes in altitude do not affect the pen's dose accuracy (Lilly Canada). Neither manufacturer page is written for Singapore, and neither replaces the leaflet in your box.

Crossing time zones: the dose day and a late dose

No label has a time-zone rule. What the labels do set is when the weekly injection can be given, how late a missed dose can still be given, and the minimum gap when the dose day moves, and those are the limits a long trip works within.

Both weekly injections can be given at any time of day, with or without meals, and the semaglutide label adds that the time of day can change without changing the dose (tirzepatide, semaglutide). A time-zone change moves the local clock by hours, while the labels' limits are counted in days.

	Tirzepatide, weekly injection	Semaglutide, weekly injection	Oral semaglutide, daily tablet
A missed dose	Give it within 4 days (96 hours); after that, skip it and keep the usual day. US and EU agree	US: give it if the next dose is more than 2 days away, otherwise skip it. EU: give it within 5 days, otherwise skip it	Skip it and take the next dose the following day. US and EU agree
Moving the dose day	At least 3 days (72 hours) between two doses. US and EU agree	US patient information: the last dose 2 or more days before. EU: at least 3 days (72 hours) between doses	Not applicable: taken daily

Sources: tirzepatide (US, EU), semaglutide injection (US, EU), oral semaglutide (US and EU).

A gap of at least 72 hours meets every day-change rule in that table, for either injection. The tirzepatide patient guide also says never to take two doses within 3 days of each other (label). For a prescription filled here, Singapore's registered instruction for a missed dose counts days since the missed dose, 5 for semaglutide and 4 for tirzepatide (NDF, semaglutide, NDF, tirzepatide), as what to do about a missed dose sets out.

If a trip means moving your dose day, agree the new day with your prescriber before you fly.

What four destinations allow you to bring in

Malaysia, Japan, Australia and Thailand each publish a general rule for medicines that travellers bring in for personal use. None of these pages names tirzepatide, semaglutide or injection pens, so each row is the general rule for prescription medicines, not a ruling on GLP-1 pens. Rules change; check the destination's official page, and your airline, before you fly.

Destination	How much, for personal use	What the page asks for	Source
Malaysia	What is reasonably required for one month's use, for you or one family member	For prescription medicines controlled under the Poisons Act 1952, show a valid prescription or a doctor's letter on arrival. Keep the dispensing label and original packaging intact	Ministry of Health Malaysia, traveller's guide dated 2019
Japan	Up to one month's supply, if the medicine is not prohibited or specially controlled in Japan	More than one month needs Import Confirmation before you enter. Medicines brought with their syringes for self-injection, under one month's supply, need no certificate; the example given is insulin	Ministry of Health, Labour and Welfare, undated
Australia	No more than a 3-month supply, for you or an immediate family member travelling with you	The prescription or a doctor's letter saying what you are taking and how much. Original packaging with dispensing labels, if possible. Anything containing a biological must be declared	Therapeutic Goods Administration, updated 27 March 2024
Thailand	Up to 30 days, the amount necessary for personal use	The general-medicines line gives the 30-day limit only; the page's certificate rules are for psychotropic medicines and medical devices	Thai Food and Drug Administration, undated

Australia's traveller's exemption lists the types of medicine it covers, including those that lower blood glucose; weight management is not named in that list (TGA). Japan's no-certificate rule for self-injected medicines gives insulin as its only example (MHLW). Whether a GLP-1 pen falls within either is for the destination's authority to say, which is why its own page is the one to check.

Bringing the pen back into Singapore falls under the Health Sciences Authority rule earlier in this article: up to three months' supply, with a copy of the prescription or doctor's letter, in labelled original packaging (HSA).

Individual circumstances vary. Nothing here replaces the Instructions for Use supplied with your medicine or the direction of the doctor who prescribed it.

Two questions this page does not answer sit alongside it. The shape of a first dose is in your first GLP-1 injection, and what to do when something seems to have gone wrong is in if you think you injected it wrong.

Common questions

Where do you inject GLP-1 medication?

The US semaglutide label names the abdomen, thigh and upper arm, with at least 2 inches (5 cm) clearance from the navel and rotation within the chosen area (label). Tirzepatide's differs: abdomen and thigh for self-injection, with the back of the upper arm stated for someone else to administer (label). Follow the leaflet packed with your own pen.

How long can a GLP-1 pen stay out of the fridge?

It depends entirely on which pen. The US labels give 28 days for the single-dose semaglutide pen (label), 56 days for the multi-dose semaglutide pen (label), 21 days for the single-dose tirzepatide pen or vial (label) and 30 days for the multi-dose tirzepatide presentation (label). These are not interchangeable.

What room temperature should the pen be kept at?

For the multi-dose semaglutide pen, the current US label states two different ranges in two different sections, and that inconsistency is unresolved (label). Follow the leaflet supplied with your own pen and ask your pharmacist to confirm it. Do not take a number from an article, including this one.

Can you fly with GLP-1 medication to or from Singapore?

Singapore's rule for bringing in your own prescribed medicine is up to three months' supply where no approval is needed, with a copy of a valid prescription or doctor's letter, in the original packaging labelled by the dispensing pharmacy with your name, the medication name and the quantity (HSA).

Do you need a doctor's letter to carry an injection pen on board?

Singapore Airlines states that a prescription or note from a registered physician is required to carry syringes or hypodermic needles on board (Singapore Airlines), and Changi lists medication accompanied by a doctor's letter among its screening exemptions (Changi Airport). Check your own airline as well.

How do you keep a weekly GLP-1 injection on schedule across time zones?

No label has a time-zone rule. Both injection labels allow the weekly dose at any time of day. To move the dose day, the tirzepatide labels require at least 3 days (72 hours) between doses, and a 72-hour gap also meets both semaglutide labels. A late tirzepatide dose can be given within 4 days; for semaglutide the EU label allows 5 days, and the US label asks whether the next dose is more than 2 days away. Agree any change of day with your prescriber before you fly.