Mysimba Tablets for weight loss
Weight loss medication with the active ingredients naltrexone and bupropion


Prices from £99.00
In stock. Simply fill in a brief questionnaire. One of our doctors will review your order and prescribe a suitable treatment. How to Order
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Mysimba is a prescription-only weight loss pill that contains the active ingredients naltrexone and bupropion. It aids weight loss by reducing your appetite so you feel fuller for longer and resist the urge to consume more calories than you need. Mysimba is taken everyday, beginning with 1 tablet per day which slowly increases to a maximum of 4 tablets a day over time.
You can request Mysimba from Asda Online Doctor. If approved, your treatment can be delivered to your home address in discreet packaging or you can choose to collect it from your nearest Asda Pharmacy 4 hours after you have received a doctor’s approval.




About Mysimba
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Mysimba is a prescription-only weight loss medication that is taken alongside positive lifestyle changes to help people achieve their weight loss goals.
Mysimba contains 2 active ingredients, naltrexone and bupropion which work together to suppress your appetite, stopping you overeating and aiding weight loss. Each Mysimba pill contains 8mg of naltrexone and 90mg of bupropion.
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The active ingredients in Mysimba, naltrexone and bupropion, work by acting on the area of the brain responsible for controlling your appetite and spending energy. Mysimba suppresses your appetite, making you feel full, so you eat less and resulting in weight loss.
Naltrexone is thought to reduce food consumption by blocking specific signals to the brain which may link eating with a feeling of reward.
Bupropion blocks the reuptake of the neurotransmitters dopamine and norepinephrine which may also be linked to rewarding behaviour, but it’s also believed to suppress appetite as well.
How long does Mysimba take to work?
Mysimba starts working as soon as you take it, but it can take a few weeks to see or feel its full effects. You should see significant weight loss after 16 weeks of treatment. If not, your doctor may suggest alternatives.
How effective is Mysimba?
Clinical trials looking at the effectiveness of Mysimba for weight loss have found that 31% of people lost at least 5% of their starting body weight compared to 12% taking a placebo. The average weight loss when taking Mysimba is 8.1% after 56 weeks of treatment.
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Each Mysimba pill should be swallowed whole with water and should preferably be taken with food.
The recommended dosage is as follows:
- Week 1 – 1 tablet once a day in the morning
- Week 2 – 2 tablets per day, 1 in the morning and 1 in the evening
- Week 3 – 3 tablets every per day, 2 in the morning and 1 in the evening
- Week 4 onwards – 4 tablets each day, 2 in the morning and 2 in the evening
The maximum recommended dose of Mysimba is 2 tablets twice a day. Your doctor will usually monitor your progress after 16 weeks to see if you should continue taking the medication.
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Mysimba is only available with a private prescription, it isn’t available over the counter or on the NHS. So, you will need to contact a private service to obtain it.
Can I buy Mysimba online?
Yes, you can request Mysimba from Asda Online Doctor by:
- Completing a short online health assessment for one of our doctors to review.
- Placing your order.
- If approved, your Mysimba order will be dispatched and sent to your home address in discreet packaging or you can choose to collect it from your local Asda Pharmacy 4 hours after a doctor’s approval.
- If your order isn’t approved, one of our doctors will contact you via your account with alternative treatment options.
Can I buy Mysimba over the counter?
No, Mysimba is only available on a private prescription, so you will need to request it from a reputable online service like Asda Online Doctor.
If you are looking for an over the counter weight loss treatment, we offer alli, a weight loss pill that contains 60mg of orlistat.
Can I get Mysimba on the NHS?
No, Mysimba is not available on the NHS. Currently, the only weight loss treatments available on the NHS are orlistat, liraglutide, and semaglutide (Wegovy).
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Very common Mysimba side effects (affecting more than 1 in 10 people) include:
- feeling sick (nausea)
- being sick (vomiting)
- constipation
- headache
Common Mysimba side effects (affecting up to 1 in 10 people) include:
- dizziness and/or vertigo
- anxiety
- feeling shaky (tremor)
- difficulty sleeping
- dry mouth
- taste changes
- tiredness and lack of energy
- ringing in the ears
- hot flushes
- pain in the upper abdomen
- feeling jittery
- difficulty concentrating
- irregular or fast heart beat
- increase in blood pressure
- excessive sweating
- rash
- itching
- hair loss
- irritability
Uncommon side effects (affecting up to 1 in 100 people) include:
- abdominal discomfort
- difficulty in getting or keeping an erection
- thirsty
- feeling hot
- burping
- indigestion
- stomach discomfort
- hypersensitivity
- hives
- abnormal dreams
- inflammation of the gallbladder
- increase in liver enzymes
- increase in appetite, weight gain
- loss of memory
- feeling nervous
- feeling spacey
- balance issues
- feeling tension, agitation, mood swings, tremors in head or limbs
- motion sickness
- heart beating fast
Rare side effects (affecting up to 1 in 1000 people) include:
- low amount of some white cells
- fits
- blood in stools
- swelling, including the lips
- jaw pain
- irregular menstrual cycle
- vaginal dryness
- sudden urge to urinate
- coldness of hands or feet
- excess loss of body fluid
- loss of red blood cells
- fainting or feeling like you are going to faint
- toothache
- dental cavities
- hernia
- risk of toxic liver injury
- hallucinations
- chest pain
- fever
- numbness or pins and needles
How long do Mysimba side effects last?
Most Mysimba side effects are temporary and go away on their own within a few weeks of starting treatment as your body gets used to the medication. Some side effects may last the entire time you’re using Mysimba and will only go away once you stop treatment.
What to do if you get Mysimba side effects
You can usually manage mild side effects at home by:
- drinking plenty of clear fluids to stay hydrated
- eating smaller, more frequent meals if you feel sick
- taking over the counter painkillers such as paracetamol or ibuprofen for headaches
- lie down if you feel dizzy until the feeling passes
- avoid coffee, cigarettes, alcohol, or recreational drugs which can make symptoms worse
If you experience any side effects that concern you or you are finding them difficult to manage, you should contact your doctor for advice.
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Do not take Mysimba if you:
- are allergic to naltrexone, bupropion or any other ingredients listed in Mysimba
- have abnormally high blood pressure that isn’t controlled with medication
- have a condition that causes fits or you have a history of fits
- have a brain tumour
- are usually a heavy drinker and you have stopped drinking alcohol or are going to while you are taking Mysimba
- have stopped taking sedatives or medication to treat anxiety
- have had bipolar disorder
- are taking any other products that contain naltrexone or bupropion
- have an eating disorder
- are currently dependent on opiates or opiate agonists
- are taking medications for depression or Parkinson’s disease
- have severe liver disease
- have endstage kidney disease
- are under 18 or over 75
Mysimba and other medications
You should let your doctor know if you are taking any prescribed, over the counter, or herbal medications before taking Mysimba.
Do not take Mysimba with:
- monamine oxidase inhibitors (medications used to treat depression or Parkinson’s disease)
- opiates and opiate-containing medications
Tell your doctor before taking Mysimba if you currently take medications for:
- depression and other mental health problems
- infections
- preventing malaria
- asthma
- allergic reactions or hayfever
- lowering blood sugar levels
- helping you sleep
- high blood pressure
- an irregular heart rhythm
- treating cancer
- HIV infection and AIDS
- epilepsy
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Mysimba isn’t the only weight loss pill available. At Asda Online Doctor, we also offer:
- orlistat – prevents the absorption of up to ⅓ of the fat you eat
- Xenical – branded version of orlistat
- alli – an over the counter version of orlistat that’s available without a prescription
If weight loss pills are not right for you, then you may be suitable for weight loss injections, such as:
- Mounjaro – a once-weekly injection that contains tirzepatide and can help people lose an average 22.5% of their starting body weight at the highest maintenance dose after 72 weeks.
- Wegovy – a semaglutide-containing once weekly weight loss injection that can help you lose 15% of your body weight at the highest maintenance dose after 68 weeks.
- liraglutide – a daily weight loss injection, formerly known as Saxenda, that can help you lose an average of 8% of your body weight after 56 weeks at the maintenance dose.
Mysimba Vs Orlistat
Mysimba and orlistat are both examples of weight loss pills when used alongside a calorie-controlled diet and exercise. Mysimba contains the active ingredients naltrexone and bupropion that act on the areas of the brain involved in controlling your appetite. People who take Mysimba can lose an average of 8.1% of their starting weight after 56 weeks of treatment.
Orlistat, on the other hand, works by stopping the body from absorbing around a third of the fat you eat, and helping it leave the body in your waste. You’ll need to take it with meals that contain fat for it to be effective. Orlistat can help 37% of people who take it lose at least 5% of their starting body weight after 12 weeks.
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Frequently asked questions
Is Mysimba dangerous?
If a doctor has approved Mysimba as a suitable medication for you, then it should be safe for you to take. All medication, including Mysimba, can cause side effects and some health risks.
What should I eat while taking Mysimba?
For the best results, you should aim to eat a calorie controlled diet when taking Mysimba and get plenty of exercise. It is also recommended that you take Mysimba with food or a small snack, like a few crackers or a sandwich to help prevent or manage nausea, which is a common side effect.
Can you drink alcohol on Mysimba?
Not really. Your doctor may recommend that you do not drink alcohol or drink as little as possible while taking Mysimba because it can increase the risk of fits, mental disorder events, or it can reduce your tolerance to alcohol. It’s also a good idea to avoid alcohol when trying to lose weight anyway, because alcohol has a lot of calories in it and can increase appetite and lead to binge eating.
Does Mysimba affect sleep?
Yes, insomnia is a commonly reported side effect of taking Mysimba. You should avoid taking Mysimba near bedtime. It is best to take Mysimba in the morning and if you are taking 2 doses, it is advisable to take 1 dose first thing in the morning, and 1 dose early in the evening.
What's the difference between Mysimba and Contrave?
Mysimba and Contrave are the same medication and work in exactly the same way, but they have different brand names. Mysimba is available in the EU and UK while Contrave is available in the US, but not in the UK.

After completing her first degree, she went on to study graduate-entry medicine at Warwick University. After graduating as a doctor, she worked within the West Midlands in Urology, Respiratory Medicine, Infectious Disease, and Psychiatry before transitioning into a full-time medical communications role.
Meet our doctorsLast reviewed: 01 Feb 2025
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Dizziness, NHS [accessed 08 January 2025]
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Mounjaro KwikPen 10mg solution for injection in pre-filled pen, emc [accessed 08 January 2025]
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Mysimba 8 mg/90 mg prolonged-release tablets, emc [accessed 07 January 2025]
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Obesity, NHS [accessed 08 January 2025]
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Safety and efficacy of naltrexone for weight loss in adult patients – a systematic review, PubMed [accessed 07 January 2025]


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