Shortages and substitutions

What a shortage actually is

Shortages of these medicines have been a recurring feature since 2023, and they are almost never about a factory catching fire. They are about demand rising faster than the world's capacity to fill injection devices, which is a genuinely slow thing to build.

The consequences have been formal as well as practical. In the UK, a National Patient Safety Alert was issued in 2023 asking prescribers to protect supply for people with type 2 diabetes and to stop initiating GLP-1 receptor agonists off-label for weight management while stocks were constrained. The European Medicines Agency published repeated shortage notices with expected recovery dates that kept moving. In the US, products sat on the FDA shortage list for long stretches, and when they came off it, the compounding permissions that had depended on that listing narrowed sharply — which changed the supply route for a very large number of people almost overnight.

Petra's summary, from running the access circles through all of it: a shortage is a policy event as much as a manufacturing one, and the people who get hurt most are the ones with the least slack — no stock at home, no money for a private alternative, no second pharmacy within reach. If that is you, none of what follows is your fault.

Finding stock without wrecking your week

What has worked for members, in order of usefulness.

Ring ahead, and ring widely. Pharmacies can usually tell you in thirty seconds whether they can order your product, and the answer varies between branches of the same chain on the same street. A polite call beats three journeys.

Build one relationship. Members who use the same independent pharmacy consistently get told when stock is expected, and sometimes get a box put aside. Chains rarely do this; independents often will.

Ask your prescriber what else is acceptable before you are desperate. There may be a different strength, a different device presentation of the same molecule, or an alternative product they would be content to switch you to. That conversation takes two minutes when planned and two weeks when it starts with an empty pharmacy shelf.

Reorder at the last carton, not the last dose. The single highest-value habit anyone in this community has, and the one thing that turns a national shortage into a mild inconvenience for you personally.

Do not stockpile beyond what your prescription supports. We say this without much moralising, because we understand the impulse entirely — but hoarding transfers the shortage to somebody with less room to manoeuvre, and fridges full of expired cartons are a story we have heard more than once.

What a substitution actually changes

Not all substitutions are the same thing, and lumping them together is how people get caught out.

Same molecule, different device or strength. The smallest change. What differs is how you set the dose, whether you attach a needle, the storage rules, and the flow check. Read the new leaflet properly rather than assuming — the device instructions are genuinely different between products.

Same molecule, different licensed brand. The same active drug licensed for a different indication may have different available strengths and a different titration schedule. Your prescriber handles that; your job is to not assume the numbers carry over.

A different molecule entirely. Semaglutide to tirzepatide, or either to liraglutide, is a new drug with a new titration, a new side-effect profile and, usually, a restart low and a climb. There is no simple conversion table between molecules, whatever you read — SURPASS-2 (Frías, NEJM, 2021) compared tirzepatide with semaglutide head to head at particular doses, but a trial comparison is not a dose-equivalence chart, and no regulator publishes one.

Licensed product to compounded or unlicensed material. This is not a substitution in the same sense at all. It is a change of supply chain, of oversight, and of what is actually known about what you are injecting. Compounded and brand: what differs lays it out and the format comparison covers the practical part.

Counterfeits, which are the real danger of a shortage

When shelves empty, falsified products appear. This is not speculation. The World Health Organization issued a medical product alert on falsified semaglutide pens found in several regions, and the UK regulator seized falsified pens after people were hospitalised — in some cases with severe hypoglycaemia, because the pens contained insulin rather than the drug on the label.

That is the specific horror of a counterfeit: it is not merely inert. It can contain something actively dangerous, in an unknown amount, in a device that looks convincing.

What protects you is boring and effective. Buy through a pharmacy that is registered in your country and can be checked on the regulator's public register. Be extremely suspicious of a social media seller, a marketplace listing, or a website that appeared this year and takes payment only by transfer. Look at the pen: wrong font, wrong batch format, a label that peels, a dial that feels loose, missing or misspelt regulatory text. If anything about it seems off, do not use it and report it to the regulator — those reports are how the alerts get issued in the first place.

Spotting a bad source is our fullest version of this, and members compare notes in sourcing safely without anyone being lectured.

Managing an actual gap

If the gap is happening anyway, there are still choices.

Tell the prescriber early — the day you find out, not the week you run out. Ask specifically: what should I do if I cannot get this before my next dose is due, and what would you want me to do about restarting when supply returns? Getting that answer in writing, even as a line in a message, means you are not improvising later. Petra's phrase is that you want a plan for the gap, not sympathy about it.

Expect the effects to fade if the gap runs into weeks. Appetite returns, food noise generally comes back, and the trial data on stopping — STEP 4 (Rubino, JAMA, 2021) and the STEP 1 extension — describes a gradual reversal rather than a cliff. Knowing that in advance takes some of the fright out of it.

Expect a restart to be handled cautiously. Prescribers commonly step you back down after a long break because tolerance fades, and that is a clinical decision, not a demotion. What to do if you miss a dose covers the shorter version and restarting after a break is where members talk about the longer one.

And keep the diary going through the gap. That record is what makes the restart conversation informed rather than a shrug.

The part that is about money and pride

Shortages make prices move, and members in every region have described paying substantially more during a squeeze — or being pushed towards a route they would never otherwise have taken, purely because it was available.

Two honest things. First, a gap in treatment is not a catastrophe, whereas a counterfeit pen can be. If the only option in front of you is a source you cannot verify, waiting is the safer choice more often than people believe in the moment.

Second, cost is a clinical fact and worth saying out loud to your prescriber. Members are far more likely to hide it than to mention it, and services sometimes have options — a different licensed product, a different pack size, a switch that costs less — that they will not offer to somebody who never says they are struggling. Paying out of pocket without panic and insurance appeals are the two guides Petra points people to, and the paying out of pocket circle is full of people who have already found the cheaper route in your country.

Nobody here thinks less of you for a gap, a switch, or a stop. Most of us have had at least one.