Orlistat and Saxenda are medications used to reduce your BMI, allowing you to lose weight effectively when lifestyle changes such as diet and exercise have been unsuccessful. Saxenda and Orlistat are both widely known names among weight loss circles, how effective are they? What are the most common side effects of the two? And do you need a prescription to access these medications?
Orlistat, otherwise known by the brand name Xenical, was approved for use by the FDA in 1999 and has been used by millions of people worldwide ever since. Liraglutide (known by the brand name, Saxenda), a much more recent addition to the US market, was approved for use as recently as 2015. Orlistat works to reduce the fat absorption of the body, allowing fat to be passed straight through the digestive system, while Saxenda uses a hormone to reduce your appetite.
| Drug Name | Orlistat | Liraglutide |
| Brand Name(s) | Xenical, Alli | Saxenda |
| Price | £36.65/month (based on 3 pack discount) | £300/month from week 5 of treatment onwards (based on 5 pen discount) |
| Form | Pill | Injection |
| Effectiveness | 2.9% weight reduction in 12 months | 5.4% weight reduction in 12 months |
| Drug Interactions | Blood thinners, HIV medications, ritonavir | Diabetes medications |
| Most Serious Side Effects | Upper stomach pain, severe nausea, unusual tiredness or weakness, dark urine, yellow eyes or skin. | Thyroid tumors, severe depression, severe rash or itching, swelling around the face, fainting or dizziness. |
Orlistat is provided as a pill that can be taken orally. It should be taken up to three times a day with meals, and can be taken up to an hour after the meal is eaten. The pill needs to be swallowed with liquid. Adults and teenagers take a pill of 120 milligrams and should not exceed this dose. In the case of children under 12 needing to take Orlistat, the dosage will be recommended by a doctor.
Saxenda is taken as an injection once a day, at any convenient time as long as the dose is consistent and regular. The injection can be taken in your stomach, upper leg or upper arm as instructed by a doctor. The Saxenda needle has specific instructions for use that will be provided in the information leaflet that comes with your prescription.
According to a study conducted in 2021, the effectiveness of the medication differs between Saxenda and Orlistat. The test group under the effects of Orlistat medication lost 2.9% of their weight over 12 months, while those using Saxenda lost 5.4%. This study used placebo groups to ensure the accuracy of their results, as weight loss methods such as reduced appetite can have differing effects depending on the subject.
All medicines carry the risk of side effects, no matter what they treat. Orlistat is a medication designed to prevent the body’s absorption of fat, while Saxenda reduces your appetite: both of these methods of weight control can cause side effects. The most common of these side effects include:
This is not a comprehensive list. For a list of rarer side effects, or for more information about how common certain side effects are, consult your doctor or the leaflet provided with your medication.
Common side effects of Orlistat vs Saxenda
| Orlistat | Saxenda |
| Diarrhea | Constipation & Diarrhea |
| Headaches | Headaches |
| Nausea | Nausea |
| Vomiting | Vomiting |
| Bladder Pain | Stomach Pain |
| Fatigue & Weakness | Fatigue |
| Fever | Dizziness |
| Cough | Reaction to Injection |
| Sweating | Low/High Blood Sugar |
| Insomnia | Changes in Blood Enzyme Levels |
| Ear Congestion | |
| Loss of Appetite | |
| Loss of Voice | |
| Muscle Aches and PainsBreathing Difficulty | |
| Nasal Congestion/Runny Nose | |
| Sore throat | |
| Sneezing |
Many medications have serious side effects. Whether a medication is cleared for use depends on how common and how serious its side effects are; so while some side effects may seem concerning, it’s highly unlikely you’ll experience them when taking Orlistat or Saxenda. Despite this, it’s important to know what side effects are serious and when to stop taking medication and talk to a doctor.
A few of the most serious side effects of Saxenda are:
A few of the most serious side effects of Orlistat are:
This is not a full list. For more information, see the information labels provided with Saxenda and Orlistat treatments.
Saxenda is exclusively available to adults over the age of 18, and should not be used for children. Saxenda will be prescribed to adults with a BMI considered overweight, and adults who suffer from weight-related health problems such as diabetes.
Saxenda should not be used if:
As with all medications, chat to your GP or arrange a free online consultation with us before starting a course of Saxenda.
You should not take Saxenda if you are taking any of the following medications:
Similarly to Saxenda, Orlistat must not be used for teenagers and children under the age of 18. Orlistat is also available to adults considered overweight with a BMI of over 30 or 28 if you have a medical condition that can be made worse by an excess of fat in the body.
Orlistat should not be used if:
Always consult your doctor if you aren’t sure whether you can take Orlistat. Your doctor will advise you of the best method of losing weight if you are unable to take Orlistat, Saxenda or any other weight loss medication.
You should not take Orlistat if you are taking any of the following medications:
Orlistat affects the effectiveness of many medications and can interact with drugs that aren’t on this list. If you take other medication, contact your GP before taking Orlistat.
Yes. Saxenda is not available over the counter in the UK, and must be purchased with a prescription. If you don’t have a prescription for Saxenda, but feel that you could benefit from a course of this medication, either chat to your GP or talk to one of our professionals to arrange a prescription today.
No. Orlistat is available over the counter without a prescription from a doctor. However, this only applies to certain dosages and your personal medical conditions and circumstances. While it’s possible to take Orlistat without consulting your GP, it’s always advisable to chat to a doctor before taking these medications.
Ultimately, the decision to take Orlistat or Saxenda is up to personal preference and the recommendations of your GP. We hope that this article has helped you to decide which medication is best for you. For more information about Orlistat, Saxenda, and other weight loss medications, check out our blog here.
