Dynamic Pricing and Mounjaro: Why the Price Changes Between Visits

What dynamic pricing means here

Dynamic pricing is any system where the price is set by demand signals rather than by cost plus a fixed margin. Airlines and hotels use it openly. In retail it can extend to personalised pricing, where two people see different prices for the same item based on device, location, browsing history or how often they have bought before.

Applied to a medicine, the objection is not that prices change; it is that the buyer cannot choose to wait. Someone titrating to a maintenance dose needs a pen roughly every four weeks, indefinitely. They cannot postpone until Tuesday, and they cannot substitute a different manufacturer, because there is only one. Ordinary price competition rewards a shopper who looks around. Demand-based pricing on a medicine mostly extracts money from a person who has no other option.

What we actually observe

Monj records each listed pharmacy’s price at each dose, along with delivery and any live code. From that record, three patterns are clear and one is not.

Clear:

• Competitive following. When one pharmacy cuts a dose, several match within days. This is the commonest cause of a price changing between your visits.
• Code churn. A headline that includes a first-order code changes the moment the code expires or is replaced, without the underlying price moving at all.
• Event repricing. Prices move around list-price changes, bank holidays and the start of the month, when demand is predictable.

Not clear: whether any UK pharmacy is running true algorithmic demand pricing on Mounjaro. We have reader reports and screenshots showing prices at individual pharmacies moving up and then back down on specific doses over short periods, which is consistent with algorithmic repricing, but equally consistent with a person adjusting a price twice. We contacted the pharmacies concerned. Until we can distinguish the two, we are not naming anyone, because getting that wrong would be unfair and we would want the same standard applied to us.

Where the line is

Changing your prices is legal and normal. Some specific practices are not, or sit close to the edge:

• Advertising a price you do not honour. Under the Consumer Protection from Unfair Trading Regulations 2008 a misleading price indication is a prohibited practice. A price that reliably rises between the landing page and the basket is exactly that.
• Fake urgency. Countdown timers, invented low-stock warnings or claimed deadlines that reset are aggressive practices under the same rules. For a medicine, they also push people into buying a dose they may not need yet.
• Reference price inflation. Showing a large discount against a regular price nobody has ever paid. The CMA has taken action on this in other sectors.
• Undisclosed subscription pricing. A low first month that silently becomes a recurring charge at a much higher rate.

None of these are unique to medicines. They matter more here because the buyer cannot walk away.

What you can do

• Check the basket, not the banner. Take the total at checkout with delivery included as the real price, and compare that.
• Compare on the day you order. A price you saw last week is history. Our price list is updated as prices move and shows totals with delivery and tested codes.
• Screenshot the advertised price before you start a consultation. If the checkout is higher, that screenshot is your evidence.
• Read subscription terms before the first payment, particularly the price after month one and how to cancel.
• Complain, in order. First the pharmacy, in writing. If the advertised price was not honoured, report it to Citizens Advice consumer service, which passes reports to Trading Standards, and to the ASA if the advertising itself was misleading. Concerns about a pharmacy’s conduct go to the GPhC.
• Tell us. Send the screenshots to Monj with the date and dose. Patterns across several readers are what turn an anecdote into something we can put to a pharmacy.