Saxenda is liraglutide, given as an injection every day, licensed for weight management. Because a dose is taken daily, a single pen is used far more often than a pen for a weekly medicine, and it is used up over a much shorter span of days. Keeping a simple personal count of doses used and doses remaining makes it easier to plan ahead rather than discovering a pen is nearly empty at an inconvenient moment.

The exact number of doses a pen provides, and how long it can be used for once opened, is set out in the official Saxenda patient information leaflet that comes with the medicine. That leaflet, not a general guide like this one, is the right place to confirm those specific figures, since packaging and device details can vary.

Counting doses versus counting days

It is tempting to assume a pen lasts a fixed number of days, but doses used and days elapsed are not always the same thing, particularly if a day was ever missed or an injection was repeated. A count that tracks actual doses taken, rather than assuming one dose per calendar day, gives a more accurate picture of how many doses are really left.

What to record when you start a new pen

  • The date the pen was first used.
  • A running tally, or tick, for each dose taken from that pen.
  • The date you expect, based on the leaflet's guidance, that the pen will need to be replaced or discarded.
  • Any note about a dose that did not go as planned, such as a partial dose or a device fault, since these can affect how many usable doses remain.

Why this supports planning ahead

A running count makes it straightforward to see, at a glance, roughly how many days of supply are left. That is useful information to have before contacting a prescriber or pharmacy about a repeat prescription, because it lets you ask with a specific number in mind rather than a rough guess. It also makes it easier to notice early if a pen is being used faster or slower than expected, which is worth mentioning at a review.

For anything beyond a personal count, it is worth knowing exactly where to check the specifics.

For anything beyond a personal count, such as exactly how many doses a pen contains, how long a pen can be used once it has been in use, or how it should be stored between injections, the official Saxenda patient information leaflet and your dispensing pharmacy are the right sources. A pharmacist can also help if a pen behaves unexpectedly or if you are unsure how many usable doses are left.

Kept consistently, a simple dose count turns pen management from a source of last-minute uncertainty into something you can plan around with confidence.

It is worth understanding why daily use changes the maths compared with a weekly medicine.

A weekly injection uses one dose from a pen roughly every seven days, which makes a rough mental estimate fairly easy to keep track of without much effort. A daily injection uses a dose every single day, so a pen that might have felt like it would last for ages can be used up far sooner than intuition suggests, especially if you have not been counting deliberately. This is one of the more common places where a daily routine catches people out: assuming pen supply mirrors how long a weekly medicine's equivalent pack would last, when the two are not comparable at all.

Linking your dose count to your daily injection log saves effort and keeps both records honest.

If you are already keeping a daily injection log, as covered elsewhere, it is worth linking the two records together. Each time you log a daily injection, a quick note of which pen it came from, and a running total for that pen, keeps the dose count effectively automatic rather than a separate task you have to remember to do. Over time, this combined record also makes it easy to check your figures: if your daily log shows twenty-eight injections since a pen was started, your dose count should broadly agree, and a mismatch is worth double-checking rather than ignoring.

A good running count also helps with ordering repeat supply with confidence.

Because daily use means pens turn over relatively quickly, it is worth building in a small buffer before contacting your prescriber or pharmacy for a repeat, rather than waiting until a pen is completely empty. A running count that tells you, for example, that you have roughly five days of supply left gives you time to arrange a repeat prescription calmly, rather than under pressure. If a repeat prescription process typically takes several days in your area, that is useful information to factor into when you start counting down.