Quick answer
What is Mysimba and can I get it in the UK?
Mysimba is a licensed prescription weight-loss tablet available in the UK on a private prescription only. It is not available over the counter and it is not funded by the NHS — NICE reviewed it in 2017 and recommended against NHS prescribing (TA494). That means you can only access it through a private doctor or online prescribing service that offers a paid consultation. If a website claims to sell it without a prescription, that is unlawful and potentially unsafe.
Important
Private prescription only — not on the NHS
Mysimba requires a private prescription. It is not available without a clinical assessment, and the NHS does not fund it. Always use a CQC-registered clinic or GPhC-registered online pharmacy when seeking a private prescription.
How it works
The dual mechanism behind Mysimba
Mysimba contains two active ingredients: naltrexone hydrochloride 8 mg and bupropion hydrochloride 90 mg, both in prolonged-release form. They work on the brain’s appetite and reward pathways at the same time.
Bupropion inhibits the reuptake of dopamine and noradrenaline, stimulating POMC cells in the hypothalamus — signals that reduce appetite. Naltrexone blocks an opioid receptor that would ordinarily switch POMC activity off, letting the appetite-suppressing effect last longer.
Together, they reduce hunger and, for many people, reduce cravings — particularly for high-calorie foods. Mysimba is intended to be used alongside a reduced-calorie diet and increased physical activity, not instead of them.
Dosing schedule
The four-week titration
| Week | Morning | Evening | Daily tablets |
|---|---|---|---|
| Week 1 | 1 tablet | None | 1 |
| Week 2 | 1 tablet | 1 tablet | 2 |
| Week 3 | 2 tablets | 1 tablet | 3 |
| Week 4 onwards | 2 tablets | 2 tablets | 4 (maximum) |
If you have not lost at least 5% of your starting body weight by week 16, clinical guidance is to stop treatment.
Who it is for
MHRA-licensed criteria
BMI of 30 or above
Classed as obesity by standard clinical criteria. Mysimba may be prescribed alongside dietary changes and physical activity.
BMI of 27 or above with a weight-related condition
For example, type 2 diabetes, high blood pressure, or high cholesterol — where losing weight may improve that condition.
It is not licensed for people under 18 or over 75.
Who should not take it
Key contraindications
Seizure history or epilepsy
Bupropion lowers the seizure threshold. Anyone with a current or past seizure disorder must not take Mysimba.
Eating disorders
Not suitable for anyone with a current or past diagnosis of anorexia nervosa or bulimia nervosa.
Current opioid use
Naltrexone blocks opioid medications. Must not be taken alongside opioid painkillers or opioid substitution therapy.
Uncontrolled high blood pressure
Blood pressure must be adequately controlled before starting. Hypertensive episodes can occur during the early weeks.
Bipolar disorder
Bupropion carries a risk of triggering manic episodes in people with bipolar disorder.
MAOIs in the last 14 days
Taking Mysimba within 14 days of a monoamine oxidase inhibitor creates a serious interaction risk.
Also not recommended during pregnancy, breastfeeding, or in people with severe liver or kidney impairment, recent heart attack, or alcohol dependency.
Getting a prescription
How to get Mysimba in the UK
Because Mysimba is a private prescription medicine, you need to complete a clinical consultation — either face to face with a private GP or through a registered online prescribing service. The consultation will check your BMI, medical history, current medications, and blood pressure.
Several CQC-registered clinics and GPhC-registered online pharmacies offer this service, including Chemist4U, ZAVA, Click Pharmacy, NowPatient, and PrivateDoc, among others. Always check the registration of any service you use.
Cost
What does Mysimba cost in the UK?
On a private prescription, Mysimba typically costs between £99 and £200 per month, including the consultation fee. Prices vary between providers. There is no NHS funding, so there is no standard prescription charge route. Always confirm the total cost before committing.
Further reading
Learn more about Mysimba
Does Mysimba work? The evidence
Trial results and what patients commonly report. Read the evidence summary.
Mysimba side effects and safety
Common effects like nausea, rare risks, and the full contraindications list. Read the safety page.
Tablet Compare may earn from qualifying purchases. This does not affect which products are covered or how they are ordered. See our affiliate disclosure.
FAQ
Common questions about Mysimba
Can I buy Mysimba over the counter?
No. Mysimba is a prescription-only medicine in the UK. It cannot be purchased without a valid prescription issued by a registered clinician.
Is Mysimba available on the NHS?
No. NICE reviewed Mysimba in 2017 (TA494) and recommended against NHS prescribing on cost-effectiveness grounds. It is only available privately.
How long does it take to see results?
Clinical guidelines use 16 weeks as the key assessment point. If you have not lost at least 5% of your starting body weight by that point, the advice is to stop treatment.
Can I take Mysimba with antidepressants?
Some antidepressants interact with Mysimba, either by increasing seizure risk or through other mechanisms. This must be assessed by your prescriber — do not start Mysimba without disclosing all current medications.
Where to get it
UK providers offering Mysimba
The following providers offer Mysimba by private prescription following an online consultation. Always verify registration (CQC or GPhC) before using any service. Prices and availability can change — confirm before ordering.
| Provider | Type | Approx. monthly cost | Prescription route |
|---|---|---|---|
| Chemist4U | Online pharmacy (GPhC registered) | From ~£99/month | Online consultation then dispensed by post |
| ZAVA | Online doctor service (CQC registered) | From ~£99/month | Online questionnaire reviewed by prescriber |
| Click Pharmacy | Online pharmacy (GPhC registered) | From ~£110/month | Online consultation then dispensed by post |
| NowPatient | Online pharmacy (GPhC registered) | From ~£99/month | Video or questionnaire consultation |
| PrivateDoc | Private GP service (CQC registered) | From ~£120/month | Online GP consultation with follow-up |
Prices shown are approximate starting prices and may exclude consultation fees or vary by supply channel. Costs of £99–£200/month are typical for the full maintenance dose once titration is complete. Always check the total cost — including any consultation or delivery charge — before committing.
Tablet Compare may earn from qualifying purchases. This does not affect which products are covered or how they are ordered. See our affiliate disclosure.
Important
Information only
Tablet Compare is information only. Mysimba is a prescription-only medicine requiring clinical assessment. Speak to a registered clinician before starting any treatment. Avoid unregulated sellers.