Mysimba Prolonged Release Tablets

Mysimba Weight Loss Tablets

What are Mysimba tablets used for?

Mysimba contains two active ingredients, naltrexone hydrochloride and bupropion hydrochloride. They’re used to help adults living with obesity or who are overweight manage their weight loss, alongside a reduced-calorie diet and regular physical activity.

Mysimba can be prescribed if you have:

• A BMI of 30 or more
• A BMI between 27 and 30 plus a weight-related condition, such as controlled high blood pressure, type 2 diabetes or raised blood fats (lipids)

You can check your BMI using our BMI calculator.

How does Mysimba work?

Mysimba works on areas of the brain involved in controlling how much you eat and how much energy your body uses. The two ingredients act on the hypothalamus, which helps regulate appetite, and on the brain’s reward system.

You may need to take Mysimba for at least 16 weeks to get its full effect. Your prescriber will review your progress at 16 weeks and then once a year. If you haven’t lost at least 5% of your starting body weight by 16 weeks, they may recommend stopping treatment. Everyone responds differently, so Mysimba reviews you read online won’t always reflect your own experience.

How effective is Mysimba?

In a 56-week clinical trial of more than 1,000 adults who were also cutting calories and increasing their activity, the average weight loss for people taking Mysimba was 5.4% of their body weight, compared with 1.3% for those taking a placebo (dummy tablet). People who completed the full 56 weeks of treatment lost an average of 8.1%.

Across four clinical trials, 50.8% of people taking Mysimba at week 16 had lost at least 5% of their starting weight. After a year, this group had lost an average of 11.3% of their body weight.

Who can use Mysimba?

Mysimba is for adults aged 18 and over. It should be used with caution if you’re 65 or older and isn’t recommended if you’re over 75.

Don’t take Mysimba if you:

• Are allergic to naltrexone, bupropion or any of the other ingredients
• Have high blood pressure that isn’t controlled with medicine
• Have a condition that causes fits (seizures) or have had fits in the past
• Have a brain tumour
• Are a heavy drinker and have just stopped drinking alcohol, or plan to stop while taking Mysimba
• Have recently stopped taking sedatives or anxiety medicines (especially benzodiazepines), or plan to stop them while taking Mysimba
• Have or have had bipolar disorder
• Take any other medicine containing bupropion or naltrexone
• Have or have had an eating disorder, such as bulimia or anorexia nervosa
• Are dependent on opiates or opiate agonists such as methadone, or are going through opiate withdrawal
• Take a monoamine oxidase inhibitor (MAOI) for depression or Parkinson’s disease, or have taken one in the last 14 days
• Have severe liver disease
• Have end-stage kidney disease

Speak to your doctor or pharmacist before taking it if you:

• Have depression, suicidal thoughts, a history of suicide attempts, panic attacks or any other mental health condition
• Have a history of mania
• Take medicines for depression, as using them with Mysimba can lead to serotonin syndrome
• Have had a serious head injury
• Drink alcohol regularly
• Regularly take medicines to help you sleep (sedatives)
• Are dependent on cocaine or other stimulants
• Have diabetes treated with insulin or tablets that can cause low blood sugar
• Have high blood pressure, as it can get worse
• Have uncontrolled coronary artery disease with symptoms such as angina, or have recently had a heart attack
• Have or have had a condition affecting blood flow to the brain (cerebrovascular disease)
• Have liver or kidney problems
• Have Brugada syndrome or a family history of cardiac arrest or sudden death
• Have been told you have an intolerance to some sugars, as Mysimba contains lactose

How to Take Mysimba

Your dose of Mysimba is increased slowly over the first four weeks until you reach a maintenance dose of two tablets in the morning and two in the evening.

1. Week 1: take one tablet in the morning.
2. Week 2: take one tablet in the morning and one in the evening.
3. Week 3: take two tablets in the morning and one in the evening.
4. Week 4 onwards: take two tablets in the morning and two in the evening.

When taking your tablets:

• Swallow each tablet whole with water. Don’t cut, chew or crush them.
• Take your tablets with food where possible.
• Avoid taking your evening dose close to bedtime, as Mysimba can make it harder to sleep.
• Don’t take more than four tablets a day.

Mysimba Side Effects

The main Mysimba side effects are listed below by how often they happen, although not everybody gets them.

Very Common Side Effects

These may affect more than 1 in 10 people:

• Feeling or being sick
• Constipation
• Headache

Common Side Effects

These may affect up to 1 in 10 people:

• Anxiety, irritability or feeling jittery
• Dizziness
• Difficulty sleeping
• Changes in taste or a dry mouth
• Tiredness or sleepiness
• Fast or irregular heartbeat
• Increased blood pressure, which can sometimes be severe
• Stomach pain
• Excessive sweating

Uncommon Side Effects

These may affect up to 1 in 100 people:

• Hives or allergic reactions
• Unusual dreams
• Mood swings, nervousness or agitation
• Indigestion or burping
• Inflammation of the gallbladder (cholecystitis)
• Difficulty getting or keeping an erection
• Increased appetite or weight gain

Rare Side Effects

These may affect up to 1 in 1,000 people:

• Swelling of the eyelids, face, lips, tongue or throat, which can make breathing very difficult (angioedema)
• Fainting or loss of consciousness
• Hallucinations
• Dehydration
• Liver damage
• Toothache or tooth decay

Serious Side Effects

Speak to your doctor straight away if you notice any of the following:

• Suicidal thoughts, thoughts of harming yourself, or feeling depressed or worse in your mood. Contact your doctor or go to hospital straight away.
• A fit (seizure), which usually involves convulsions and loss of consciousness. Stop taking Mysimba.
• Signs of an allergic reaction, such as swelling of the face, lips, tongue or throat, difficulty swallowing or breathing, fever, rash, joint or muscle pain or hives. Stop taking Mysimba.
• A serious skin reaction, such as red, itchy spots spreading from the limbs (erythema multiforme), severe blistering and bleeding of the lips, eyes, mouth, nose or genitals (Stevens-Johnson syndrome), or a widespread red, scaly rash with blisters and fever (acute generalised exanthematous pustulosis). Stop taking Mysimba.
• Severe muscle cramps, pain or weakness, which can be a sign of muscle breakdown (rhabdomyolysis).
• A lupus-like skin rash or worsening lupus symptoms, especially on skin exposed to the sun.
• Agitation, hallucinations, a high temperature, fast heartbeat, muscle stiffness or loss of coordination while also taking an antidepressant, as these can be signs of serotonin syndrome.

For a full list of side effects, see the Mysimba Patient Information Leaflet.

If you get any side effects, you can report them through the MHRA Yellow Card Scheme.

Mysimba Ingredients

Active ingredients: Each tablet contains 8mg naltrexone hydrochloride (equivalent to 7.2mg naltrexone) and 90mg bupropion hydrochloride (equivalent to 78mg bupropion).

Other ingredients: Microcrystalline cellulose, hydroxypropyl cellulose, lactose anhydrous, lactose monohydrate, cysteine hydrochloride, crospovidone type A, magnesium stearate, hypromellose, edetate disodium, colloidal silicon dioxide, indigo carmine aluminium lake (E132), poly(vinyl alcohol), titanium dioxide (E171), macrogol 3350 and talc.

Mysimba vs Other Weight Loss Medications

Mysimba works differently from most other prescription weight loss medicines, which copy the effects of natural gut hormones:

• Mysimba is a tablet taken twice a day at the full dose. It contains naltrexone and bupropion, which act on areas of the brain that control appetite and energy use.
• Mounjaro is a once-weekly injection containing tirzepatide, which works in a similar way to the gut hormones GLP-1 and GIP.
• Wegovy injections are taken once a week and contain semaglutide, which works in a similar way to GLP-1.
• Wegovy tablets contain the same active ingredient, semaglutide and are taken once daily.
• Foundayo is a once-daily tablet containing orforglipron, which also works in a similar way to GLP-1.
• Alli capsules contain orlistat, which reduces how much fat your body absorbs from food.

Our pharmacists can help you decide which weight loss treatment is right for you based on your health and medical history.

Mysimba Warnings and Precautions

• Your blood pressure and heart rate will be checked before you start Mysimba and during treatment. If either rises significantly, you may need to stop.
• You’ll need to stop any opiate medicines, including codeine, morphine and some cough and cold remedies, at least 7 to 10 days before starting Mysimba.
• Naltrexone blocks the effects of opiates. Taking higher doses of opiates to override this can cause dangerous, life-threatening opiate poisoning.
• After you stop taking Mysimba, you may be more sensitive to low doses of opiates.
• Drinking a lot of alcohol while taking Mysimba may raise your risk of fits and mental health side effects and lower your tolerance to alcohol. If you drink heavily, don’t stop suddenly, as this can also trigger a fit.
• Some medicines can increase the risk of fits when taken with Mysimba, including steroid tablets, antimalarials, quinolone antibiotics, tramadol, theophylline and sedating antihistamines.
• Mysimba can affect how well digoxin works and may interact with some medicines for blood pressure, heart rhythm, Parkinson’s disease, epilepsy, HIV, cancer, heart disease and stroke, so your doctor may need to monitor you or adjust your dose.
• Mysimba can make you feel dizzy or sleepy. Don’t drive, use tools or operate machinery until you know how it affects you, and don’t drive at all if you faint, have muscle weakness or have a fit.
• Keep Mysimba out of the sight and reach of children.