Mysimba is a prescription-only weight loss medication
Mysimba can help you lose weight by reducing your appetite, so you feel more full after eating less food. Mysimba is taken every day, and you should start to see the effects of it working within a few weeks of starting treatment. You should also aim to improve your diet and start regularly exercising alongside taking Mysimba to get the best results.
What is Mysimba?
Mysimba is a prescription medication that’s used to help you lose weight if you’re overweight. It’s a tablet that is taken once or twice a day, depending on what you’ve been prescribed. Mysimba reduces your appetite, so you feel more full after less food, which makes you eat less. This can help you safely and effectively lose weight, especially when taken alongside a healthy diet and regular exercise.
How does Mysimba work?
Mysimba works by making you feel more full, so you eat less food, which helps you lose weight. It does this because its ingredients, naltrexone and bupropion, affect the part of your brain which controls your appetite.
How long does Mysimba take to work?
Mysimba starts working as soon as you take it, but you might not see the full effects of the medication until you’ve been taking it for a few weeks.
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 long does Mysimba last?
Mysimba lasts for as long as you are taking it, and a pack of 112 tablets should last you around 5 weeks when you first start taking it, then 4 weeks once you’re on the maintenance dose.
How effective is Mysimba?
Mysimba has been shown to be effective in helping people lose weight when taken in combination with exercise and a healthy diet. Studies have shown the average weight loss of people taking Mysimba is between 3.7% and 5.7% of their starting weight.
How to take Mysimba
Take Mysimba tablets whole with a glass of water. Always take the dose that you have been prescribed by your doctor.
The starting dose of Mysimba is usually 1 tablet each morning. This is then gradually increased to 2 tablets twice a day after taking Mysimba for 4 weeks.
You can take up to 4 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.
Who can take Mysimba?
Mysimba may be suitable for you if you are over 18 and have a BMI (body mass index) of 30 or above.
People may also be prescribed Mysimba if they have a BMI lower than 30 but are at risk of developing diabetes or other conditions related to being overweight.
Where can I buy Mysimba
Mysimba is available in most Irish pharmacies with a valid prescription which can be provided by IMC registered online doctors like ZAVA.
Can I buy Mysimba online?
You can buy Mysimba online, but you need a prescription from a doctor to do so. To get yours, start a consultation with ZAVA, and if appropriate, we can issue you a prescription.
Can I buy Mysimba over the counter?
You can not buy Mysimba over the counter as it is a prescription medicine. This is to make sure 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.
Mysimba side effects
Common Mysimba side effects:
- Hot flushes
- Nausea or vomiting
- Taste changes
- Changes in blood pressure
- Hair loss
If you get any of these side effects from Mysimba, you should speak to your doctor. Do not stop taking Mysimba without speaking to your doctor first.
Uncommon side effects from taking Mysimba include:
- Abnormal dreams, agitation and mood swings
- Balance disorders
- Motion sickness
- Abdominal discomfort
- 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
- Irregular menstruation
- Chest pain
- Blood and lymphatic system disorders
- Loss of consciousness
- Lip swelling and toothache
- Bleeding from your back passage
- 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 Mysimba and see a doctor immediately if you get these side effects:
- Difficulty breathing
- Dizziness or loss of consciousness
- An allergic rash
- Chest pain
- 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 are getting them. If you’re getting serious side effects that are unmanageable or you’re worried you’re having a reaction to Mysimba, you should go to the hospital or contact emergency services.
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
- Use opiates or certain other medications like some antidepressants
- Take concomitant treatment containing bupropion or naltrexone
Mysimba may not be suitable for people who:
- have a history of bipolar disorder
- are taking certain antidepressants
- have a history of depression
Seek medical advice immediately if you have any thoughts about harming yourself or others while taking Mysimba.
Medication that interacts with Mysimba
Mysimba may not be suitable for you if you take:
- Opioid analgesics like codeine, morphine or tramadol
- Drugs metabolised by cytochrome P450 (CYP) enzymes
- Medication for HIV
- Anti platelet medication
- Medication used to treat Parkinson’s disease
Always let your doctor know about any medication you are currently taking before starting Mysimba. This is to make sure Mysimba won’t interact with these.
Dr Babak Ashrafi Clinical Lead for Service Expansion
Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.Meet our doctors
Last reviewed: 08 Dec 2022
How to use Naltrexone-Bupropion Tablet, Extended Release (2022) WebMD [Accessed 25/04/2022]
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]