Get a prescription for Mysimba

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Mysimba for Weight Loss

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Get a prescription for Mysimba

Mysimba is a weight loss medication that reduces your appetite, so you’ll feel full after eating less food. This reduces the urge to eat, which can help you lose weight. You take Mysimba every day, and you should start to notice the effects of Mysimba within a few weeks of taking it. To get the most out of Mysimba, we recommend taking it alongside a healthy diet and regular exercise.

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Start order for Mysimba

To place an order, fill in a brief questionnaire. One of our doctors will review your order and prescribe a suitable treatment.


112 tablets (1 Month) £99 (£0.89 per tablet)

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About MySimba

Mysimba is a prescription weight loss treatment for people who are overweight and comes as a tablet that is taken once or twice every day. Unlike other weight loss tablets, which work by changing how your body stores fat, Mysimba works by suppressing your appetite. This means you feel less hungry less often, and you don’t need to eat as much food to feel full. This can help you lose weight by reducing the amount of food you eat.

Mysimba contains naltrexone and bupropion, which affect the part of your brain which controls your appetite. It works by making you feel less hungry by reducing the amount of food you need to eat to feel full. This can help to curb eating habits like snacking between meals.

How long does Mysimba take to work?

Mysimba starts working straight away, but it can take a few weeks to see the full effects of this medication. You can expect to lose 5% of your starting weight after 16 weeks (4 months) of use. If you lose less than 5% of your body weight, your doctor will advise you to stop Mysimba and may suggest alternative weight loss treatments. You’ll be more likely to see better results if you stick to a healthy diet and active lifestyle.

How long does Mysimba last?

The effects of Mysimba continue for as long as you're taking the medication.
When you first start taking Mysimba, you’ll be given a pack of 112 tablets which will last around 5 weeks.

How effective is Mysimba?

In many studies, the average weight loss recorded by patients taking Mysimba was around 3.7-5.7% of their weight. However, these results did vary depending on whether the patients took their medication alongside exercise and a healthy diet.

You should take your tablets alongside a meal and swallow them with plenty of water. The recommended dose will vary between people and will be set by your doctor when you receive the medication.

Recommended dosage

In most cases, you’ll usually start with one tablet each morning and gradually increase this to two tablets twice a day after four weeks. You can take up to four tablets a day, so your dosage may increase over time. Your doctor will be able to talk you through how to take the 8mg/90mg dose before and during your course of treatment.


If you miss a dose of Mysimba, you should never take double to make up for the one you missed. Just skip the missed dose and continue to take your medication as normal.

Who can take Mysimba?

People who are over the age of 18 and have a body mass index (BMI) of 30 or above can take Mysimba if their doctor prescribes it. People who have a BMI lower than 30 will be considered for Mysimba if they’re at risk of developing diabetes or have other weight related medical conditions.

You can buy Mysimba from most UK registered pharmacies. You can go in-store or online, using services like Superdrug Online Doctor. This treatment does require a prescription to purchase online, or at a pharmacy, so you’ll need to speak to a medical professional if you want to start taking Mysimba.

Can I buy Mysimba online?

You can buy Mysimba online from UK registered pharmacies, like Superdrug Online Doctor. To get yours, you’ll need to complete a short and simple medical form so our doctors can make sure Mysimba is right for you. If they think it is, they’ll write up a prescription for you. You can then order Mysimba to your door.

Can I buy Mysimba over the counter?

Mysimba is not available to buy over the counter as it’s a prescription drug. This is because a doctor needs to review your health to make sure this medication is right for you. 
Your doctor will need to evaluate your mental health and your physical health. Overeating due to stress and anxiety can be a reason for weight gain, which means Mysimba may not be effective or may need to be combined with counselling or therapy.

Can I get Mysimba on the NHS?

Mysimba is only available through a private prescription in the UK and is not available on the NHS.

Each person will react differently to Mysimba and can get side effects. If you experience any side effects, they will usually be mild and disappear once you stop taking the medication. Common side effects include:

  • Anxiety 
  • Constipation 
  • Dizziness
  • Headaches
  • Hot flushes  
  • Insomnia
  • Nausea or vomiting
  • Palpitations 
  • Tiredness
  • Taste changes
  • Tinnitus
  • Changes in blood pressure
  • Itching
  • Rashes
  • Sweating
  • Hair loss
You should contact your doctor immediately if you experience any of the above side effects after taking Mysimba. These symptoms should go away on their own, and you shouldn’t stop taking the medication without speaking to your doctor about it first.


Uncommon side effects you may experience from taking Mysimba include: 

  • Hypersensitivity 
  • Abnormal dreams, agitation and mood swings
  • Balance disorders
  • Amnesia 
  • Tremor
  • Motion sickness 
  • Abdominal discomfort 
  • Indigestion
  • Burping or belching
  • Hepatic enzyme increase
  • Gallbladder inflammation
  • Changes to your kidney blood tests
  • Erectile dysfunction
  • Increase thirst and appetite 
  • Urticarial skin rash
  • Rare side effects you may experience include: 
  • Jaw pain 
  • Dehydration
  • Irregular menstruation 
  • Chest pain 
  • Fever
  • Blood and lymphatic system disorders 
  • Hallucinations
  • Loss of consciousness
  • Lip swelling and toothache 
  • Seizures 
  • Bleeding from your back passage
  • Hernias
  • Abdominal pain
  • Changes to how often you pass urine
  • Vaginal dryness, bleeding and changes to your periods

If you experience any uncommon or rare side effects after taking Mysimba, you should consult your doctor urgently. You must stop taking your medication and see a doctor immediately if you develop:

  • Difficulty breathing
  • Dizziness or loss of consciousness
  • An allergic rash
  • Chest pain
  • Seizures
  • Hallucinations
  • Severe upper abdominal pain
  • Mouth or lip swelling

What to do if you get Mysimba side effects

If you experience any mild side effects and they don’t go away after a month, you should discuss this with your doctor. If you’re experiencing any severe pain or discomfort or serious side effects listed above, you should go to the hospital or contact emergency services.
Certain conditions or medications can interact with this medicine and make it less effective or potentially unsafe. You should not take Mysimba if you:

  • Are pregnant or trying to conceive
  • Have a history of an eating disorder
  • Suffer from severe liver or kidney disease 
  • Experience uncontrolled hypertension 
  • Have ever had a seizure
  • Have a nervous system tumour 
  • Experience benzodiazepine or alcohol withdrawal 
  • Take concomitant treatment containing bupropion or naltrexone

Other people who should avoid taking Mysimba include: 

  • Anyone who has a history of bipolar disorder 
  • Patients who are taking antidepressants - especially those on or who have taken monoamine oxidase inhibitors (MAOI)  in the last 14 days
  • Anyone with a history of depression 
  • Anyone taking opiate medication or methadone

Bupropion is found in Mysimba. This is similar to ingredients found in certain antidepressants, which could increase the risk of suicidal thoughts and behaviour. You should contact a doctor immediately for help if you have any thoughts about harming yourself or others.

Medication that interacts with Mysimba

There are a range of medications that interact with Mysimba. You should tell your doctor if you’re taking any medications before you start Mysimba. Mysimba may not be suitable for you if you take any of the following: 

  • Antidepressants
  • Opioid analgesics 
  • Drugs metabolised by cytochrome P450 (CYP) enzymes
  • Anti-epileptics
  • Medication for HIV
  • Anti platelet medication
  • Medication used to treat Parkinson’s disease 

If you’re unsure if you’re taking the above, then speak to your doctor during your consultation or mention it on your questionnaire. You should also make them aware of any other medicine you’re taking, even if they’re not on this list.

If Mysimba isn’t suitable for you, we have several alternative medications you can consider for weight loss at Superdrug Online Doctor. They contain different active ingredients, which will affect you in different ways. Alternatives you can consider include:

  • Xenical (Orlistat)
  • Saxenda
  • Mysimba vs Xenical (Orlistat)
Xenical and Mysimba are both effective forms of weight loss treatments. Xenical has been on the market for some time and is a popular choice. The active ingredient in this treatment is orlistat, which reduces the amount of fat your body absorbs during digestion. Xenical is a branded prescription treatment. Unlike Mysimba, it can be purchased over the counter after a registered health professional assesses your suitability.

Mysimba vs Saxenda

Saxenda and Mysimba are both weight-loss drugs. The active ingredient in Saxenda is liraglutide, which makes you feel fuller for longer, reducing your food intake. This medicine is only available in injection form. Just like Mysimba, you need a prescription to buy and take Saxenda. 

Mysimba vs Alli

Alli is an over-the-counter treatment that is taken to aid weight loss. It only contains 60g of orlistat, which is half the amount found in Xenical so a prescription isn’t required. Alli prevents a quarter of dietary fat from being digested to reduce weight gain. However, due to the low dosage, it isn’t as effective as Xenical, Mysimba or other prescription medications for weight loss. However, it’s much cheaper and easier to obtain.
Mysimba (2022) European Medicines Agency [Accessed 25/04/2022]
Mysimba 8mg/90mg prolonged-release tablets (2021) EMC [Accessed 25/04/2022]
Mysimba - The New Treatment for Weight Loss (2018) Foresight Medical Centre [Accessed 25/04/2022]
Naltrexone and Bupropion (2019) MedlinePlus [Accessed 25/04/2022]
What Is the Difference Between Xenical and Mysimba? (2022) ExpressPharmacy [Accessed 25/04/2022]
Which Weight Loss Pill is Most Effective? (2019) doctor-4-u [Accessed 25/04/2022]

About Online Doctor

We're a service that helps you order treatments online from UK-registered doctors with free, discreet, to-your-door deliveries.

See our About Us page to learn more.

Reviewed by: Dr Clair Grainger in line with the Superdrug Online Editorial Process.

GMC no. 7041314

Dr Grainger studied at the University of Edinburgh and worked in hospitals before becoming a GP. She has an interest in respiratory, and sexual and reproductive health.

Last reviewed on: 17/05/22