Semaglutide and Liraglutide are both medications that belong to the same family of drugs – GLP-1 receptor agonists.
Both are available in injection form and have been proven to be effective for the treatment of type 2 diabetes in adults.
However, there are some differences between the two medicines that are fairly important to know about.
Semaglutide is better known as the once-weekly injection, Wegovy, but it also has a tablet formula, known as Rybelsus.
On the other hand, Liraglutide is known as the daily injection or under the brand names Victoza (for the treatment of type 2 diabetes) and Saxenda (which was approved as an obesity treatment in the UK a few years ago).
Semaglutide is licensed to treat both obesity and type 2 diabetes in the UK, with weight loss licensing being a very recent development.
Like Liraglutide, Semaglutide injections can be prescribed to weight loss patients with a BMI of 30 or above or to those with a risk of complications like type 2 diabetes.
What is the difference between Semaglutide and Liraglutide?
There are a couple of differences between Semaglutide and Liraglutide, the main one being that Semaglutide is a longer-acting medicine, meaning that it can be injected once a week instead of once a day.
On the surface, this makes Semaglutide look like a more convenient option, but there is more to consider if you’re trying to decide between the two treatments.
Semaglutide was developed to be a longer-acting alternative to Liraglutide and other similar medicines, so broadly speaking, the main difference between the two medications is the elimination half-life.
Liraglutide injections like Saxenda generally have an elimination half-life of 13 hours, hence why it’s administered once a day at the same time, whilst Semaglutide injections have a 7-day elimination half-life, allowing it to be administered once weekly instead.
This increase in elimination half-life is owed to a modification in the structure of Semaglutide which means it cannot be broken down by enzymes in the blood as easily as other GLP-1 receptor agonists.
In addition to this, there are differences in efficacy between the two medications which will be discussed in more detail shortly.
Is Saxenda as effective as Semaglutide?
If you’re talking in terms of weight loss, Semaglutide injections have actually been found to be more effective for weight loss than Saxenda.
There are two key studies where these findings were discovered.
In the first study, (O’Neil.P et al, 2018) participants were subject to a 52 week randomised trial to investigate how efficient Semaglutide injections were for weight loss when compared with Liraglutide injections and a placebo.
Participants either received daily doses of Semaglutide, Liraglutide, or a placebo injection.
Liraglutide (Saxenda) was given to participants initially with a dose of 0.6mg daily and titrated up to the therapeutic dose of 3.0mg daily by an increase of 0.6mg per week (the usual dose for this medication).
Semaglutide, however, was given in daily doses of 0.05mg, 0.1mg, 0.2mg, 0.3mg or 0.4mg.
This was increased every 4 weeks for one group of Semaglutide participants.
Findings from this study showed that overall, weight loss was greater in patients taking more than 0.2mg of Semaglutide daily compared to daily doses of Liraglutide or placebo, and higher doses of Semaglutide yielded a greater loss.
By the end of the year-long study, those given Semaglutide injections lost on average 11.2-13.8% of their starting weight, whereas Liraglutide participants lost around 7-8%.
The study ended up revealing that doses of 0.2mg Semaglutide daily provided significant body weight reductions when compared with doses of Liraglutide.
A second study, (Lingvay.I et al, 2018) took place over 26 weeks and compared Semaglutide injections with Liraglutide and placebo with patients who had type 2 diabetes.
Although the purpose of this study wasn’t to evaluate weight loss, it still showed that participants taking Semaglutide lost more weight than those on Liraglutide and placebo, and the number of people losing 5-10% of their body weight was greater amongst the Semaglutide groups than any others.
In Lingvay’s study, 22-76% of Semaglutide participants lost 5% of their initial starting weight by the end of the 26 week trial compared to just 16-42% of Liraglutide participants.
In addition to this, a 10% total weight reduction was achieved by 5-38% of Semaglutide participants, compared to just 0-8% with those taking Liraglutide injections.
Both of these studies show Semaglutide to be more effective for weight loss than Liraglutide and could be the reason behind why the medicine is currently undergoing more clinical trials to evaluate its efficacy as a weight-loss drug.
In terms of which medication is more effective for the treatment of type 2 diabetes, this would depend on your symptoms and how much management they need.
Both medicines work in a very similar way within the body, but you should speak to your diabetic nurse or consultant about which one would be best for you based on your blood glucose levels and whether or not you are able to manage it conservatively with diet, exercise, and potentially metformin.
Weekly injections versus daily injections
Weekly and daily injections both have their pros and cons, depending on your lifestyle and routine.
Some people find it easier to remember an injection if they have to take it every day, whilst others don’t like injecting themselves daily and would prefer to administer it once a week.
There is no right or wrong answer to whether weekly injections (Semaglutide or Wegovy) are superior to daily injections (Liraglutide or Saxenda) if the only factor in your decision is how often you want to administer the medication.
If you’re looking for something that you can take at the same time each day, then you may benefit from taking a look at Saxenda as a treatment, but if you’d rather only inject once a week, Wegovy is probably the better option for you.
However, it’s important to know that this shouldn’t be your only deciding factor when you’re choosing between medications, and ultimately, the final decision on your treatment is down to the prescriber or consultant that you speak to.
Differences in side effects between Semaglutide and Liraglutide
Most GLP-1 receptor agonists share similar side effects due to the fact that they all work in a very similar way within the body.
However, some people may be more susceptible to certain side effects than others.
It’s worth noting that most side effects are gastro-intestinal related and most do subside with time, but if you find that you aren’t able to tolerate the side effects, you should make an appointment to talk with your prescriber about what steps you should take.
Semaglutide and Liraglutide share many of the same side effects due to how they work within the gut.
It’s unlikely that you would experience hypoglycaemia (low blood sugar levels) with either of these injections as long as you aren’t taking any other medicines that might affect your blood glucose.
You should mention any and all medicines that you’re currently taking to the prescriber during your consultation so that they can make an informed decision about your treatment in your best interests.
Semaglutide does seem to have fewer side effects than Liraglutide in total (perhaps due to the fact that it is only injected once a week instead of daily), but the potency of Semaglutide may mean that these side effects could be more intense.
Unfortunately, there is no way of knowing how a medicine will affect you until you begin to take it, but this is why GLP-1 receptor agonists are generally titrated up to the therapeutic dose over the course of several weeks, as it reduces the risk of experiencing severe or debilitating side effects.
Can you take Semaglutide and Saxenda together?
As Semaglutide and Saxenda contain active ingredients that are very similar to each other, it is not safe to take the two treatments together.
They both affect your blood sugar levels, and doubling up on this type of medication can lead to complications if your blood sugar drops too low.
As they both work in a very similar way within the body and would interact with each other, the risk of severe side effects would also increase, which may cause serious illness.
Can I switch from Saxenda to Wegovy or vice versa?
If you’re already taking either Semaglutide or Saxenda and are thinking of changing your medication, you should first have a consultation either with your GP or our healthcare professionals to discuss your options and which would be the most suitable treatment for you.
It is possible to switch between treatments, as long as you take notice of when you had your last injection.
If you’re switching from Saxenda (Liraglutide) to Wegovy (Semaglutide), you can start your Wegovy injections the day after your last dose of Saxenda.
If you’re switching from Wegovy to Saxenda, you should wait a week as you normally would between injections before you’re able to start your Saxenda pen.
Of course, it’s important to note that your treatment plan may differ from this, depending on your personal circumstances.
It’s important that you follow the instructions given to you by your prescriber during a medication transition, as they will have taken your current health and other circumstances into account when writing your prescription.
What works for you may not work for everyone else, so trust in your prescriber and take their advice.
