What are the best tablets for weight loss?

Finding the right weight loss tablets can feel overwhelming when you are faced with countless options, conflicting information, and the very real frustration of previous failed attempts. Whether you have tried countless diets that simply did not stick or you are looking for that extra support to kickstart your journey, understanding which tablets actually work and which ones are safe is absolutely essential. In the UK, there are both prescription medications and over-the-counter supplements available, but not all of them deliver on their promises, and some may even pose risks to your health. This comprehensive guide cuts through the noise to give you evidence-based information about the most effective weight loss tablets available in Britain today, helping you make an informed decision that could genuinely transform your relationship with weight management.

Quick Summary

Weight loss tablets in the UK range from prescription-only medications to over-the-counter supplements, with varying levels of effectiveness and safety. Understanding which option suits your individual needs depends on factors including your BMI, medical history, and weight loss goals.

• Orlistat (Xenical/Alli) is the most widely available prescription weight loss tablet in the UK, blocking fat absorption
• Mysimba combines bupropion and naltrexone to reduce appetite and cravings
• Over-the-counter supplements have limited evidence but may provide modest support
• Prescription tablets typically require a BMI of 30 or above, or 27 with weight-related conditions
• All weight loss tablets work best when combined with diet modifications and increased physical activity

Table of Contents

• Prescription Weight Loss Tablets Available in the UK
• How Weight Loss Tablets Work in Your Body
• Over-the-Counter Weight Loss Supplements
• Who Can Take Weight Loss Tablets
• Side Effects and Safety Considerations
• Weight Loss Tablets vs Injectable Treatments
• Key Takeaways
• When to Seek Professional Advice
• Frequently Asked Questions

Prescription Weight Loss Tablets Available in the UK

When it comes to prescription weight loss tablets in the UK, there are two main medications that have been approved by the MHRA (Medicines and Healthcare products Regulatory Agency) and are commonly prescribed: Orlistat and Mysimba. These medications have undergone rigorous clinical testing and have demonstrated their effectiveness in helping people achieve meaningful weight loss when used alongside lifestyle modifications. Orlistat, sold under the brand names Xenical (prescription strength) and Alli (lower dose, pharmacy-only), has been available in the UK for over two decades. It works by preventing your body from absorbing approximately one-third of the fat you eat. This means that undigested fat passes through your digestive system and is eliminated naturally. The prescription-strength version contains 120mg of the active ingredient and is taken three times daily with meals containing fat. Clinical studies have shown that people taking Orlistat alongside a reduced-calorie diet lost an average of 2.9kg more than those following diet alone over 12 months. Mysimba is a newer addition to the UK weight loss tablet market, combining two active ingredients: bupropion and naltrexone. Bupropion is traditionally used as an antidepressant and smoking cessation aid, while naltrexone is used to treat alcohol and opioid dependence. Together, these medications work on the brain's reward and appetite centres, helping to reduce food cravings and control hunger. The treatment involves a gradual dose escalation over four weeks, eventually reaching the maintenance dose of two tablets twice daily. For those seeking alternatives to tablets, many people are now exploring injectable weight loss treatments which offer different mechanisms of action and may suit certain individuals better.

• Orlistat 120mg (Xenical) requires a prescription and is taken with each main meal
• Orlistat 60mg (Alli) is available from pharmacies without a prescription for adults with BMI over 28
• Mysimba requires a prescription and involves a four-week dose escalation period
• Both medications should be used alongside a reduced-calorie diet and exercise programme
• Regular follow-up appointments are recommended to monitor progress and side effects

How Weight Loss Tablets Work in Your Body

Understanding how weight loss tablets actually work can help you set realistic expectations and choose the most appropriate option for your situation. Different medications target different biological pathways, and knowing these mechanisms helps explain why certain side effects occur and how to maximise the benefits of treatment. Orlistat works exclusively in your digestive system, specifically in your stomach and small intestine. It acts as a lipase inhibitor, meaning it blocks the enzymes (lipases) that normally break down dietary fat into smaller molecules that can be absorbed. Without these enzymes functioning properly, about 30% of the fat you eat passes through your system undigested. This creates a calorie deficit because fat is the most calorie-dense nutrient, containing 9 calories per gram compared to 4 calories per gram for protein and carbohydrates. The medication does not enter your bloodstream in significant amounts, which is why its side effects are primarily gastrointestinal rather than systemic. Mysimba operates very differently, working directly on your brain chemistry. Bupropion increases levels of dopamine and noradrenaline in the hypothalamus, the region of the brain that regulates appetite and energy expenditure. This helps reduce hunger signals and increase feelings of satiety. Naltrexone, meanwhile, blocks opioid receptors in the brain that are involved in the pleasure response to eating, particularly when it comes to highly palatable foods high in sugar and fat. Together, these two drugs create a synergistic effect that helps break the cycle of emotional eating and food cravings that many people struggle with. The effectiveness of these tablets is closely linked to lifestyle factors. Research consistently shows that people who combine medication with dietary changes and increased physical activity achieve significantly better results than those who rely on tablets alone. This is why healthcare providers always prescribe these medications as part of a comprehensive weight management programme.

• Orlistat prevents approximately 30% of dietary fat from being absorbed
• The medication works locally in the gut without significantly entering the bloodstream
• Mysimba affects brain chemicals involved in appetite regulation and reward pathways
• Combining medication with lifestyle changes produces the best long-term outcomes
• Neither medication works instantaneously – consistent use over months is necessary to see results

Over-the-Counter Weight Loss Supplements

The UK market is flooded with over-the-counter weight loss supplements, ranging from herbal preparations to fibre-based products. While these options are more accessible than prescription medications, it is important to approach them with realistic expectations and an understanding of the limited evidence supporting most of these products. Glucomannan, derived from the konjac root, is one of the few over-the-counter supplements that has received approval from the European Food Safety Authority for weight loss claims. It works by absorbing water in the stomach to create a feeling of fullness, potentially helping you eat less. To be effective, it must be taken with plenty of water before meals. Clinical studies have shown modest benefits, with users losing approximately 0.8kg more than placebo groups over several weeks. Conjugated linoleic acid (CLA) is another popular supplement that has shown some promise in research settings. It may help reduce body fat while preserving lean muscle mass, though the effects are generally modest. Green tea extract, containing catechins and caffeine, has been studied for its potential to boost metabolism slightly. However, the weight loss benefits observed in studies are typically small – usually less than 2kg over 12 weeks – and individual responses vary considerably. Fibre supplements like psyllium husk can help with weight management by promoting satiety and improving digestive regularity. While not specifically marketed for weight loss, increasing fibre intake is a sensible addition to any weight management plan. It is worth noting that many supplements marketed aggressively for weight loss contain ingredients with little or no scientific support, and some may even be harmful. Understanding how stress affects appetite can also help you address underlying factors that may be contributing to weight gain, potentially reducing your reliance on supplements altogether.

• Glucomannan has EU-approved claims for contributing to weight loss when taken before meals
• CLA may provide modest fat reduction benefits but results are inconsistent
• Green tea extract can slightly boost metabolism but effects are generally small
• Many OTC supplements lack robust scientific evidence for their weight loss claims
• Always check for MHRA registration and avoid products with unproven or dangerous ingredients

Who Can Take Weight Loss Tablets

Not everyone who wants to lose weight is a suitable candidate for weight loss tablets. In the UK, there are specific eligibility criteria that must be met before prescription medications can be dispensed. These guidelines exist to ensure that medications are used safely and appropriately, targeting those who are most likely to benefit while minimising risks. For prescription-strength Orlistat (Xenical), you typically need a BMI of 30 or higher to be eligible. However, if you have a BMI of 28 or above and have weight-related health conditions such as type 2 diabetes, high blood pressure, or high cholesterol, you may also qualify. The pharmacy-only version (Alli) is available to adults aged 18 and over with a BMI of 28 or higher. Your pharmacist will conduct an assessment before selling this medication. Mysimba has similar BMI requirements but also has additional contraindications that must be considered. It should not be used by people with uncontrolled high blood pressure, a history of seizures, eating disorders like bulimia or anorexia, or those currently taking certain medications including MAO inhibitors. People with a history of bipolar disorder should use Mysimba with caution due to the bupropion component. Age is another factor – most weight loss tablets are not recommended for those under 18 or over 75, though individual circumstances may vary. Pregnant and breastfeeding women should avoid weight loss medications entirely. If you have kidney or liver problems, your healthcare provider may need to adjust doses or recommend alternative approaches. If you are wondering about eligibility requirements for other treatments, similar criteria often apply across different weight loss medications.

• Prescription Orlistat typically requires a BMI of 30 or above, or 28 with comorbidities
• Mysimba has additional contraindications including seizure history and uncontrolled hypertension
• Age restrictions generally apply – most tablets are for adults 18-75 years old
• Pregnancy and breastfeeding are absolute contraindications for weight loss tablets
• Medical conditions affecting the liver or kidneys may require dose adjustments or alternative treatments

Side Effects and Safety Considerations

Every medication comes with potential side effects, and weight loss tablets are no exception. Being aware of what to expect can help you manage side effects effectively and know when to seek medical advice. The nature of side effects varies significantly between different types of weight loss tablets. Orlistat's side effects are primarily gastrointestinal and are directly related to its mechanism of action. Because undigested fat passes through your system, you may experience oily or fatty stools, oily spotting on underwear, increased frequency of bowel movements, and flatulence with discharge. These effects are more pronounced when you eat high-fat meals, which serves as a natural reminder to follow the recommended low-fat diet. Many people find that these side effects become more manageable as they learn to adjust their fat intake accordingly. Mysimba can cause different types of side effects due to its action on brain chemistry. Common side effects include nausea, constipation, headache, dizziness, and dry mouth. These are usually mild and tend to improve over the first few weeks of treatment as your body adjusts. However, because it contains bupropion, there is a small increased risk of seizures, particularly at higher doses or in people with predisposing factors. Changes in mood and behaviour should be monitored, especially in the early stages of treatment. For guidance on managing side effects from weight loss treatments, understanding what is normal when starting treatment can help you distinguish between expected effects and symptoms that require medical attention.

• Orlistat side effects are mostly digestive – oily stools, increased bowel movements, flatulence
• Eating high-fat meals while taking Orlistat significantly worsens gastrointestinal side effects
• Mysimba may cause nausea, headaches, dizziness, and mood changes
• Both medications require monitoring, especially in the early weeks of treatment
• Serious side effects are rare but should be reported to a healthcare professional immediately

Weight Loss Tablets vs Injectable Treatments

The weight loss treatment landscape has expanded significantly in recent years with the introduction of injectable GLP-1 receptor agonists like semaglutide (Wegovy) and tirzepatide (Mounjaro). Understanding how tablets compare to these newer options can help you make an informed choice about which treatment might be most suitable for your needs. In terms of effectiveness, injectable treatments generally produce greater weight loss than tablets. Clinical trials have shown that semaglutide can help people lose 15% or more of their body weight, while tirzepatide has demonstrated even higher efficacy in some studies. By comparison, Orlistat typically produces around 5-10% weight loss, and Mysimba falls somewhere in between. However, greater efficacy often comes with higher costs and different considerations. Tablets offer the convenience of oral administration, which many people prefer over weekly injections. They also tend to be more affordable, particularly Orlistat, which has been available as a generic medication for some time. For those who are needle-phobic or simply prefer taking pills, tablets remain an attractive option. Additionally, some people may not be eligible for injectable treatments due to specific medical conditions or contraindications. The choice between tablets and injections often depends on individual factors including your starting BMI, how much weight you need to lose, your budget, and your comfort level with different administration methods. Some people start with tablets and progress to injectables if they need additional support, while others may find that tablets provide sufficient assistance when combined with lifestyle changes. You can explore more about where to find affordable Mounjaro if you are considering injectable options.

• Injectable GLP-1 treatments typically produce greater weight loss than tablets
• Tablets offer convenience of oral administration without needles
• Cost is generally lower for tablets, especially generic Orlistat
• Some people may not be eligible for injectables due to specific contraindications
• Treatment choice should be personalised based on individual needs and circumstances

Comparison Table: UK Weight Loss Tablets and Supplements

Product	Type	How It Works	Expected Weight Loss	Common Side Effects	Availability
Orlistat 120mg (Xenical)	Prescription	Blocks fat absorption in gut	5-10% body weight over 12 months	Oily stools, flatulence, frequent bowel movements	Prescription only
Orlistat 60mg (Alli)	Pharmacy-only	Blocks fat absorption in gut	3-5% body weight over 6 months	Oily stools, flatulence (milder than Xenical)	Pharmacy counter (BMI 28+)
Mysimba	Prescription	Reduces appetite and cravings via brain chemistry	5-8% body weight over 12 months	Nausea, headache, dizziness, constipation	Prescription only
Glucomannan supplements	OTC	Creates fullness by absorbing water	0.5-1kg over 4-8 weeks	Bloating, gas, digestive discomfort	General sale
CLA supplements	OTC	May reduce body fat storage	Variable (limited evidence)	Digestive upset, may affect insulin sensitivity	General sale
Green tea extract	OTC	May slightly boost metabolism	1-2kg over 12 weeks (modest)	Caffeine-related effects, liver concerns at high doses	General sale

Key Takeaways

• Orlistat and Mysimba are the main prescription weight loss tablets available in the UK, each with different mechanisms and side effect profiles
• OTC supplements like glucomannan may offer modest support but have limited evidence compared to prescription medications
• Eligibility for prescription tablets typically requires a BMI of 30 or above, or 27-28 with weight-related health conditions
• All weight loss tablets work best when combined with a reduced-calorie diet and increased physical activity
• Injectable treatments like Wegovy and Mounjaro may offer greater weight loss but come with different considerations including cost and administration method

When to Seek Professional Advice

While this guide provides comprehensive information about weight loss tablets, there are certain situations where professional medical advice is essential. You should consult a healthcare provider before starting any weight loss medication if you have existing health conditions, are taking other medications, or have concerns about your suitability for treatment. Seek immediate medical attention if you experience severe or persistent side effects while taking weight loss tablets. For Orlistat, this includes severe abdominal pain, signs of liver problems such as yellowing of the skin or eyes, or symptoms of kidney stones. For Mysimba, warning signs include seizures, severe mood changes, thoughts of self-harm, or allergic reactions such as difficulty breathing or swelling of the face and throat. You should also speak to a healthcare professional if you are not losing weight after several months of treatment, as this may indicate the need for a different approach or further investigation. If you have a history of eating disorders, weight loss medications should only be considered under close medical supervision, if at all. Additionally, anyone considering combining weight loss tablets with other supplements or medications should check for potential interactions first. Remember that weight loss tablets are not a magic solution – they are tools that work best as part of a comprehensive approach to weight management. A healthcare provider can help you develop a personalised plan that addresses your specific needs and circumstances, increasing your chances of achieving sustainable results.

Frequently Asked Questions

Are weight loss tablets safe to take long-term?

Prescription weight loss tablets like Orlistat and Mysimba have been studied for long-term use and are generally considered safe when taken under medical supervision, though regular check-ups are recommended to monitor for side effects.

Can I buy prescription weight loss tablets online in the UK?

Yes, you can purchase prescription weight loss tablets from registered online pharmacies in the UK following an online consultation with a qualified prescriber who will assess your suitability.

How much weight can I expect to lose with weight loss tablets?

Results vary significantly between individuals, but clinical trials show prescription medications can help achieve 5-10% body weight loss over 12 months when combined with diet and exercise changes.

Do weight loss tablets work without exercise?

While weight loss tablets can produce some results without exercise, combining them with physical activity and dietary changes significantly improves outcomes and helps maintain weight loss long-term.

Scientific References

• National Institute for Health and Care Excellence (NICE). Obesity: identification, assessment and management. Clinical guideline CG189. Available at: https://www.nice.org.uk/guidance/cg189
• NHS UK. Weight loss pills. Available at: https://www.nhs.uk/conditions/obesity/treatment/
• Medicines and Healthcare products Regulatory Agency (MHRA). Orlistat: updated prescribing advice. Available at: https://www.gov.uk/drug-safety-update