Mysimba is a prescription-only weight loss medication

Mysimba weight loss tablets are a prescription-only medication. They can help you lose weight by reducing your appetite, so you feel more full after eating less food. This helps you to follow a diet and exercise regime and to lower your calorie intake without feeling hungry.

Mysimba diet pills are taken every day, starting with 1 pill each morning. Your Mysimba dosage is increased over 4 weeks, to reduce the risk of side effects like nausea (feeling sick). You should start to see Mysimba results within a few weeks of starting treatment.

You’ll get the best results by exercising regularly and eating well while taking Mysimba tablets. You can buy Mysimba online from regulated online doctor services, like ZAVA.

In stock. Delivery: 1-5 days.

from £99.00

How much does Mysimba cost?

Pack Size Price
8 mg/90 mg - 112 tablet(s) - 1 month £99.00
Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 17 Oct 2023

About Mysimba

What is Mysimba?

The Mysimba appetite suppressant is a prescription medication. It can be used to help you lose weight if you’re overweight or obese. Mysimba tablets reduce your appetite, so you feel more full after less food, which makes you eat less. It does this by working on the part of your brain responsible for hunger.

Mysimba can help you safely and effectively lose weight, when taken alongside a healthy diet and regular exercise. Mysimba tablets are taken once or twice a day, depending on what you’ve been prescribed. A typical Mysimba result is a weight loss of at least 5% of your body weight after 4 months (16 weeks).

What is Mysimba used for?

Mysimba tablets only have one use and this is weight loss. You can be prescribed Mysimba weight loss tablets if you’re overweight and are struggling to lose weight through diet and exercise alone.

Your doctor may also recommend Mysimba diet pills if you have another health condition that is caused by your weight, or is more dangerous if you’re overweight.

Mysimba tablets can help you lose weight safely, without going on a fad diet.

How does Mysimba work?

Mysimba tablets contain the active ingredients naltrexone hydrochloride and bupropion hydrochloride. These work on the areas of your brain that are responsible for food intake, hunger levels, and energy.

When you take Mysimba and reduce your calorie intake, you can eat less without feeling hungry. This makes it easier to make healthy lifestyle changes for safe and effective weight loss, such as snacking less.

How long does Mysimba take to work?

Mysimba tablets start working as soon as you take them, but you might not see the full effects of the medication until you’ve been taking it for a few weeks. This is because it needs some time to build up in your system, and in the first few weeks you’ll be slowly increasing your Mysimba dosage.

You should expect to lose about 5% of your starting weight after 4 months of taking Mysimba. If you don’t lose 5% of your starting weight, your doctor may suggest an alternative weight loss treatment. It’s also important to maintain a healthy diet and regular exercise to achieve your weight loss goals with Mysimba.

How effective is Mysimba?

Mysimba tablets have been shown to be effective in helping people lose weight when taken in combination with exercise and a healthy diet. This 2020 study found that taking Mysimba diet pills helped significantly more people lose at least 5% of their starting weight than taking a placebo.

Another study found that weight loss achieved by taking naltrexone and bupropion was maintained throughout a 56-week trial.

What are the benefits of Mysimba?

The benefits of taking Mysimba tablets include:

  • losing weight and maintaining a healthy weight
  • a less frustrating weight loss experience, especially if you find it difficult to deal with hunger while reducing your calorie intake
  • feeling less hungry, which makes it easier to reduce snacking and decrease your appetite levels over time
  • reducing the risk of health conditions that are more likely if you’re overweight or obese, such as high blood pressure, heart disease, stroke, heart attack, and diabetes

Is Mysimba effective for weight loss?

Yes, Mysimba weight loss results are usually positive, with most people losing at least 5% of their initial body weight, if not more (Onakpoya et al, 2020). You can improve Mysimba results by exercising regularly (for at least 150 minutes a week) and eating a balanced diet, avoiding high-fat and high-sugar food and drinks.

Mysimba ingredients – bupropion-naltrexone

Each Mysimba tablet contains 2 active ingredients: naltrexone hydrochloride (8mg) and bupropion hydrochloride (90mg). The combination of naltrexone/bupropion has been found to be an effective weight loss treatment.

Naltrexone binds to opioid receptors which causes you to feel fewer food cravings and reduces your appetite. Bupropion binds to norepinephrine and dopamine receptors, having an antidepressant effect that also helps reduce appetite.

How to take Mysimba

Take your Mysimba tablets whole with a glass of water. Always take the Mysimba dosage that you’ve been prescribed by your doctor. You’ll usually take Mysimba once or twice a day.

Who can take Mysimba?

Mysimba weight loss tablets may be suitable for you if:

  • you’re over 18
  • you have a BMI (body mass index) of 30 or above
  • you have a BMI of 27 to 30, and are at risk of developing diabetes or other conditions related to being overweight

Our doctors will take your BMI and all of your medical history into consideration and may prescribe off-label when making a decision about treatment.

Does Mysimba work immediately?

As soon as you start taking Mysimba tablets, they will start to work. It will take a little time for the active ingredients to build up in your system and for you to see weight loss results, but you should start to notice their effect within the first few days.

How long can you stay on Mysimba?

You can stay on Mysimba for as long as a doctor agrees it’s helpful for you. You’ll be monitored by your doctor to check your Mysimba tablets are working and are helping you to lose weight.

If you haven’t lost 5% of your body weight after 4 months, your doctor may tell you to stop using Mysimba and try another weight loss medication instead.

Can you just stop taking Mysimba?

You should try to wait at least 4 months before stopping Mysimba tablets, as it’s been shown that they take around this long to reach their full effect. Although, you should stop right away if you experience serious side effects. See the ‘Mysimba side effects section’ for more information on this. If you are not having serious side effects and you want to stop taking Mysimba, speak to your doctor first.

Mysimba dosage: What strength is Mysimba?

The starting dose of Mysimba is usually 1 tablet each morning. This is then gradually increased to 2 tablets, twice a day (4 tablets a day), after taking Mysimba for 4 weeks. Each tablet contains 8 mg of naltrexone hydrochloride and 90 mg of bupropion hydrochloride.

You can take up to 4 Mysimba tablets a day, but only if your doctor has prescribed you this dose. Your doctor will take you through how to take your medication and what doses to take during your treatment.

If you miss a dose, never take a double dose to make up for it. Skip the dose you missed and continue to take your medication as you normally would.

Where can I buy Mysimba tablets in the UK?

If you have a prescription for Mysimba you can pay to get it filled at most UK pharmacies. Since Mysimba is not normally offered by the NHS, you will need to get a private prescription and pay full prices for your treatment.

You can also buy Mysimba in the UK online, through trusted and regulated online doctor services, like ZAVA. To buy Mysimba, you’ll need approval from a doctor. This is to make sure Mysimba tablets are safe and suitable for you to take.

Can I buy Mysimba online?

Yes, you can buy Mysimba online, but you need approval from a doctor to do so.

  • Complete a short online questionnaire about your health
  • Log in or sign up and place a request for treatment
  • A doctor will review your request to make sure it’s right for you
  • If approved, your treatment will be posted to your preferred address

Ordering from ZAVA is quick and easy. All orders come with free standard delivery and follow up advice from doctors available through your account.

If you’re searching for the cheapest Mysimba in the UK, be aware that you may be purchasing from an unregulated seller. This is illegal and could be dangerous, as you won’t be getting Mysimba treatment checked for you by a doctor.

Can I buy Mysimba over-the-counter?

No, you can’t buy Mysimba over the counter as it is a prescription medicine. This is to make sure a doctor checks it is safe and suitable for you before you take it. Your doctor will review your health, weight, and any other medications you are taking before prescribing Mysimba tablets.

Mysimba side effects

Mysimba tablets, like all medications, can cause side effects. This is why your Mysimba dosage is increased gradually, to minimise the risk of side effects like nausea and headaches.

Common Mysimba side effects include:

  • anxiety
  • constipation
  • dizziness
  • headaches
  • hot flushes
  • insomnia
  • nausea (feeling sick) or vomiting (being sick)
  • heart palpitations
  • tiredness
  • taste changes
  • tinnitus
  • changes in blood pressure
  • itching
  • rashes
  • sweating
  • hair loss

If you get any of these Mysimba side effects, you should speak to your doctor. Do not stop taking Mysimba without speaking to your doctor first.

Uncommon Mysimba side effects include:

  • hypersensitivity
  • abnormal dreams, agitation and mood swings
  • balance disorders
  • amnesia
  • tremors
  • motion sickness
  • abdominal discomfort
  • indigestion
  • burping or belching
  • hepatic enzyme increase
  • gallbladder inflammation
  • changes to your kidney blood tests
  • erectile dysfunction (ED)
  • an increase in thirst and appetite
  • urticarial skin rash

Rare Mysimba side effects include:

  • jaw pain
  • dehydration
  • irregular periods
  • chest pain
  • fever
  • blood and lymphatic system disorders
  • hallucinations
  • loss of consciousness
  • lip swelling and toothache
  • seizures (fits)
  • 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 get any of these side effects after taking Mysimba, you should speak to a doctor urgently.

Stop taking your Mysimba tablets and see a doctor straight away if you get these side effects:

  • 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

Most Mysimba side effects should go away as your body gets used to the medication, but you should always let your doctor know if you’re experiencing them. If you’re getting serious side effects that are unmanageable or you’re worried you’re having an allergic reaction to Mysimba, you should go to the hospital or call 999.

Mysimba side effects can usually be managed at home. For instance, if you feel sick or are throwing up while taking Mysimba, try to eat smaller portions, avoid fatty, greasy meals and keep hydrated. You can also take painkillers alongside Mysimba if you get a headache.

What are the risks of Mysimba?

Mysimba is generally safe if a doctor has approved treatment for you. Mysimba is not safe for everyone, though, and it may not be right for you if you have an existing health condition (contraindication).

Mysimba contraindications

You should not take Mysimba tablets 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
  • use opiates or certain other medications like some antidepressants
  • take concomitant treatment containing bupropion or naltrexone

Mysimba tablets may not be suitable for people who:

  • have a history of bipolar disorder
  • are taking certain antidepressants
  • have a history of depression

Speak to a doctor or call 111 or 999 straight away if you have any thoughts about harming yourself or others while taking Mysimba.

Is Mysimba dangerous?

Mysimba is not dangerous if approved for you, otherwise, it would not be available in the UK. It could be dangerous if taken by someone who has not been prescribed it, as you may have another health condition that could interact with Mysimba.

Your doctor will always make sure that a medication is safe for you to take before prescribing it. You can also speak to a doctor if you get any Mysimba side effects that worry you.

It’s natural to feel a bit worried when taking a medication for the first time. You don’t know how you might react and you may experience some side effects. Remember that a doctor would only approve treatment if they thought it was safe for you and you can always contact them if you have any concerns about the safety of your medication.” Dr Babak Ashrafi, Clinical Lead for Service Expansion.

Medication that interacts with Mysimba

Mysimba tablets may not be suitable for you if you take:

  • antidepressants
  • opioid analgesics like codeine, morphine, or tramadol
  • drugs metabolised by cytochrome P450 (CYP) enzymes
  • anti-epileptics
  • medication for HIV
  • antiplatelet medication
  • medication used to treat Parkinson’s disease

Always let your doctor know about any medication you are currently taking before starting Mysimba diet pills. This is to make sure Mysimba won’t interact with these.

Mysimba and alcohol

You shouldn’t take Mysimba if you’re a heavy drinker and have just stopped, or are planning to stop while taking Mysimba. This is because you’re more likely to get serious side effects, such as a seizure or mental health disorder. Mysimba can also reduce your alcohol tolerance.

Your doctor may recommend avoiding alcohol or only drinking small amounts while taking Mysimba. If you currently drink a lot of alcohol and haven’t disclosed this to your doctor, speak to them straight away.

Mysimba alternatives

If you cannot take Mysimba, it hasn’t worked for you, or you just want to know what other Mysimba alternative treatments are available, we have a range of weight loss treatments at ZAVA.

Below we look at some other weight loss medications, including weight loss tablets and weight loss injections, so you can make an informed decision about which you’d prefer to try.

Mysimba vs Saxenda

If you are trying to choose between Mysimba or Saxenda, the comparison table below can give you a better view of each weight loss medication.

You can also get Wegovy, which is another weight loss injection containing semaglutide, rather than liraglutide. If you’re currently taking Saxenda, you can switch from Saxenda to Wegovy.

Mysimba Saxenda
Active ingredient



Recommended dosage

2 tablets, twice a day


Common side effects

headache, nausea, vomiting, constipation

headache, nausea, vomiting, constipation





Effective at helping people lose more weight than diet and exercise alone

67.5% of people lost 5% or more of their initial body weight after 12 weeks


From £99 for 1 month’s supply (112 Mysimba tablets)

From £57.00 per pen

Requires a prescription?



What it’s approved for

Weight loss

Weight loss

Mysimba vs Orlistat

If you are trying to choose between Mysimba or orlistat, the comparison table below can give you a better view of each weight loss medication. Orlistat is an unbranded tablet, which can also be found under the branded name Xenical.

Mysimba Orlistat
Active ingredient



Recommended dosage

1 tablet, twice a day

1 tablet (120mg), up to 3 times a day

Common side effects

Headache, nausea, vomiting, constipation

Headache, abdominal pain, flatulence, oily/fatty stools



Up to 3 times a day, only with meals containing fat


Effective at helping people lose more weight than diet and exercise alone

Can help people lose 50% more weight than through diet and exercise alone


From £99 for 1 month’s supply (112 Mysimba tablets)

From £24.99 for 2 weeks of capsules

Requires a prescription?



What it’s approved for

Weight loss

Weight loss

Mysimba vs Ozempic

If you are trying to choose between Mysimba or Ozempic, the comparison table below can give you a better view of each weight loss medication.

Mysimba Ozempic
Active ingredient



Recommended dosage

1 tablet, twice a day

1 mg

Common side effects

Headache, nausea, vomiting, constipation

Headache, nausea, vomiting, constipation



Once a week


Effective at helping people lose more weight than diet and exercise alone

66.9% of people lost at least 5% of their initial body weight after 24 months


From £99 for 1 month’s supply (112 Mysimba tablets)

From £129.00 per pen

Requires a prescription?



What it’s approved for

Weight loss

Treating and managing type 2 diabetes

Conclusion: Is Mysimba a good pill for me?

Mysimba tablets have been found to be an effective way to lose weight, especially while following a diet and exercise regime. The only way to know for sure if Mysimba weight loss tablets are a good choice for you is by giving them a go or speaking to one of our doctors. We’ll make sure Mysimba is right for you before approving treatment.

Frequently asked questions

Can you take Mysimba at night?

You’ll usually take your Mysimba tablets in the morning and evening. You can start taking Mysimba at night but once you move up to 2 tablets a day you’ll need to take them in the morning too. Don’t take your Mysimba too late at night if you’re making up for a missed dose. In this case, just skip your missed dose and carry on as normal from the time your next Mysimba tablet is due.

How long do Mysimba side effects last?

This is different for everyone. You may only notice Mysimba side effects for the first few weeks, but they can last a few months. Your doctor can lower your Mysimba dosage if you’re getting bothersome side effects.

Some people get no Mysimba side effects at all. Most side effects are mild and should go away after a while.

Is Mysimba safe to take?

Yes, Mysimba diet pills are a safe and suitable treatment, as long as you’ve been prescribed them. You can get Mysimba safely online, but you’ll still need approval from a doctor and you’ll need to use a regulated service, like ZAVA.

Which is better, Mysimba or Saxenda?

Both are effective weight loss treatments, so this depends on your budget, suitability, and whether you’d like to take weight loss pills or an injection. If you try one and don’t get the effect you were hoping for, you may be able to switch to the other. You can also check out the comparison table in the ‘Mysimba vs Saxenda’ section for more information.

Is Mysimba the same as orlistat?

No, Mysimba is not the same as orlistat. It contains different active ingredients and works differently. We have a comparison table under the ‘Mysimba vs orlistat’ section if you want to know more about both treatments.


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