Updated: October 2026
In short: There are only a few weight-loss pills with documented effects: orlistat (over the counter as Alli, prescription-only as Xenical) reduces fat absorption and in studies led to about 4.8 instead of 2.3 kilograms of weight loss per year. With over-the-counter dietary supplements such as green tea extract, garcinia or L-carnitine, the effects in studies are small or inconsistent, and some carry risks. Prescription tablets and metformin belong in a doctor's hands. As of: October 2026.
If you search for weight-loss pills, you find advertising promises, pharmacy shelves and prescription medicines side by side. Here we separate them cleanly: what is approved, what is a dietary supplement, what do studies show, and where are the risks? The article covers injections Weight-Loss Injections: Effects and Side Effects.
Which weight-loss pills really work?
The effect is mainly documented for approved medicines. Dietary supplements for weight loss don't have to prove their effectiveness before sale. The consumer advice centre (Verbraucherzentrale) writes that there is no official check of effectiveness before sale and that health claims on weight loss are only permitted for very few ingredients.
| Product | Prescription? | What the sources show | Main risks |
|---|---|---|---|
| Orlistat 60 mg (Alli) | No, over the counter (EMA) | 4.8 kg per year versus 2.3 kg on placebo | Oily stools, urgent need to go, bloating; not during pregnancy, breastfeeding, with ciclosporin, warfarin |
| Orlistat 120 mg (Xenical) | Yes | Stop treatment if 5% weight loss isn't reached after 12 weeks | Digestive complaints |
| Glucomannan | No (dietary supplement) | 2014 meta-analysis: minus 0.22 kg, not significant | Bowel obstruction if too little fluid |
| Green tea extract | No (dietary supplement) | 2023 network meta-analysis: minus 1.25 kg, low certainty of evidence | Liver damage, blood pressure, eye pressure |
| L-carnitine | No (dietary supplement) | 2020 meta-analysis: minus 1.21 kg | Not conclusively assessed |
| Garcinia cambogia | No (dietary supplement) | 2020 meta-analysis: minus 1.34 kg, interval borderline (minus 2.62 to minus 0.07 kg) | Liver, cardiovascular, digestion |
| Rybelsus (semaglutide tablet) | Yes | Approved for type 2 diabetes, not for weight loss | Nausea, diarrhoea |
Status of the analysis: checked October 2026. The figures come from the sources named below.
Which weight-loss pills are available at the pharmacy without a prescription?
According to the EMA, Alli with the active ingredient orlistat 60 mg is approved without a prescription, for adults with a BMI of 28 or above. Orlistat blocks fat-digesting enzymes, so that part of the dietary fat is excreted undigested. The EMA cites about a quarter of dietary fat. It's taken up to three times a day with main meals, together with a slightly calorie-reduced, lower-fat diet. Use should not exceed six months.
In clinical studies, Alli users lost on average 4.8 kilograms per year, and placebo 2.3 kilograms. That's a difference of around 2.5 kilograms, so a modest additional effect. The most common side effects concern digestion: oily stools, sudden urgency, bloating. According to the EMA, they occur less often with a low-fat diet. Pregnant and breastfeeding women, people with malabsorption or liver disease and anyone taking ciclosporin or blood thinners such as warfarin should not use it. If you take medication, always ask at the pharmacy.
Do over-the-counter dietary supplements for weight loss work?
Mostly hardly. A review of herbal products in 2020 concluded that the evidence isn't sufficient to recommend any of them for weight loss. Only Phaseolus vulgaris (bean extract) showed a statistically, but not clinically, significant effect. In detail:
- Glucomannan: The consumer advice centre counts it among the few substances with an approved claim and warns of bowel obstruction if you drink too little with it. A 2014 meta-analysis, on the other hand, found minus 0.22 kilograms compared with placebo, not statistically significant.
- Green tea extract: A 2014 meta-analysis found minus 0.78 kilograms (not significant), a 2023 network meta-analysis minus 1.25 kilograms with low certainty of evidence. The consumer advice centre warns of liver damage up to liver failure, raised blood pressure and raised eye pressure. In the EU, an upper limit of 800 milligrams of EGCG per day applies.
- L-carnitine: A 2020 meta-analysis gave minus 1.21 kilograms, mainly in people with overweight. That's a small effect.
- Garcinia cambogia: A 2020 meta-analysis found minus 1.34 kilograms with a borderline confidence interval. The consumer advice centre sees no scientific support and points to risks for the liver and cardiovascular system.
- Caffeine: A dose-response meta-analysis (13 studies, 606 participants) saw greater loss of weight and fat mass with increasing caffeine amounts. The consumer advice centre warns that caffeine in combination with other substances can worsen high blood pressure and a racing heart.
- Chitosan: Is meant to bind fat, but according to the consumer advice centre also binds vitamins A, D, E and K.
- Bitter orange (synephrine): No effect on weight documented, risks for heart and circulation, especially with caffeine.
- CLA: For conjugated linoleic acid, we found no robust figure from a verified source in our research and therefore give none.
Are there prescription weight-loss pills?
Yes, but they are prescribed by doctors. Orlistat 120 mg (Xenical) is, according to the EMA, approved for adults with a BMI of 30 or above, or 28 or above with risk factors; anyone who hasn't lost at least 5 percent of their weight after 12 weeks should end treatment. The NHS gives the same limit after three months.
The EMA describes Wegovy now also as a tablet to take by mouth. In the OASIS 1 study (Lancet 2023, 667 adults without diabetes, 68 weeks), participants on oral semaglutide 50 mg lost on average 15.1 percent, versus 2.4 percent on placebo. Digestive complaints occurred in 80 percent versus 46 percent on placebo. This study tested 50 mg; which dose is approved in the tablet is in the prescribing information and with your doctor.
Rybelsus also contains semaglutide, but is only approved for type 2 diabetes. The EMA lists weight loss as an observed side effect, not as an indication.
Does metformin help with weight loss?
Metformin is approved for type 2 diabetes. The NHS also lists polycystic ovary syndrome (PCOS) as a use, but doesn't mention an approval for weight loss. If it's prescribed for weight loss, that's use outside the approval (off-label), which can only be decided by a doctor.
The evidence shows a small effect: a 2024 meta-analysis of 49 studies in adults without diabetes and a BMI of 25 or above found an average reduction in BMI of 0.56 kg/m² on metformin compared with placebo. The authors speak of modest weight loss. Common side effects according to the NHS are nausea, vomiting, diarrhoea, abdominal pain and loss of appetite, and in the long term vitamin B12 deficiency. Never take metformin without a doctor's prescription.
How dangerous are weight-loss pills from the internet?
The Rhineland-Palatinate State Investigation Office reports that supposedly harmless diet pills repeatedly contain highly potent, undeclared drugs. Named are sibutramine, whose authorisation in Europe was suspended in 2010 and which can endanger blood pressure and heart, and phenolphthalein, a former laxative with a cancer risk. For autumn 2025 and spring 2026, the office lists new warnings about individual products.
The Hamburg consumer advice centre describes a large and opaque market that harms users despite all promises. Don't spend your money on products that promise quick weight loss without a change in diet. More on online offers for injections is in the article Peptides for Weight Loss.
What helps safely instead?
The basics remain boring and effective: a moderate calorie deficit, enough protein, fibre, exercise and sleep. The article shows how many calories you need Calorie Needs for Weight Loss. Our calorie calculator helps with estimating, and Losing Weight Healthily: Nutrition, Tips and Recipes provides the framework. If overweight is a burden on your health, medical advice is the first step, not the pill.
Pairs well with frank.
As foods to try: Soups from frank. as a meal and cold-pressed juices for in between. Neither is a medicine or a weight-loss product.
You might also like
- Losing Weight Healthily: Nutrition, Tips & Recipes
- How Many Calories Do You Need Per Day to Lose Weight Healthily?
- Weight-Loss Injections: Effects, Side Effects and Use
Frequently asked questions about weight-loss pills
Are there weight-loss pills that really help?
Orlistat (Alli over the counter, Xenical on prescription) is approved and documented, with a modest additional effect of around 2.5 kilograms a year compared with placebo. With most dietary supplements, the effects are small or uncertain.
Which weight-loss pills are available at the pharmacy without a prescription?
Alli (orlistat 60 mg) is, according to the EMA, available without a prescription for adults from BMI 28. There are also numerous dietary supplements whose effectiveness is not checked before sale.
Does green tea extract work for weight loss?
If at all, only a little: minus 1.25 kilograms in a network meta-analysis with low certainty of evidence. Concentrated extracts can damage the liver; the EU upper limit is 800 milligrams of EGCG per day.
Is Rybelsus a weight-loss pill?
No. According to the EMA, Rybelsus is approved for type 2 diabetes. Weight loss is observed as a side effect, but is not an approved indication.
Can I take metformin for weight loss?
Metformin is not approved for weight loss. A doctor's prescription outside the approval is possible; the effect is small in studies. Don't take it without medical supervision.
Are weight-loss pills from the internet dangerous?
Such products can contain undeclared drugs such as sibutramine, which endanger blood pressure and heart. The Rhineland-Palatinate State Investigation Office has been warning about such products for years.
Note: This article is for general information and does not replace medical advice, diagnosis or treatment. You make decisions about medication, dosage or stopping together with your doctor. If you have symptoms or pre-existing conditions, are pregnant or take medication, please speak to them first.
