Why user ratings matter - but aren’t everything
Online reviews show how real people feel day to day, but they don’t replace clinical trials. Side-effects can be over- or under-reported, and some posts may be old. Use ratings as a conversation starter, not a final verdict of what’s the best weight loss pill.
Best weight loss pills based on reviews
Alli (Orlistat 60mg)
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Alli is a lower-dose version of Orlistat available without a prescription. It helps block some of the fat you eat from being absorbed, supporting gradual and sustainable weight loss when used alongside a reduced-calorie, low-fat diet.
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117 reviews with an average rating of 6.1/10¹
49% of reviewers report a positive experience, 32% report negative
A typical comment:
“Been using this medication for a little over a week. My observations are the following: 1. Do not fart unless you are on a toilet. Unless you don’t mind the orange skid marks. 2. Keep a toilet brush handy to clean your bowl after you flush your gross stool. Unless you don’t mind a dirty toilet. 3. Again, hold those farts in until you find a toilet. Just avoid being around people smoking unless you want to cause a fire from the gasses you release."
Side effects like gas, diarrhoea, bloating, upset stomach, and constipation are fairly common
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Up to 5% weight loss
Contains a lower 60 mg dose of Orlistat and similarly reduces fat absorption, though slightly less potent than prescription strength.
Best results are seen with lifestyle adjustments - low‑fat, reduced‑calorie diet plus regular activity.
Suitable for people seeking gradual, self-managed weight loss without prescription.
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As an over-the-counter option, Alli can be more affordable than Xenical in the UK, typically around £29-49 for 84 capsules (~1-2 months).
Xenical (Orlistat 120mg)
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Xenical is the branded version of Orlistat and works by reducing the amount of fat your body absorbs from food. Taken with a low-fat diet and medical support, Xenical can help you lose weight more effectively and improve long-term health outcomes.
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120 reviews with an average rating of 8.2/10 ²
73% of users report a positive experience, just 8% report negative experiences
One user shared:
"25, female, started off at 15st 7lbs or 99kg or 217lbs (I’m 5’7). Originally was looking for a quick fix but realistically when it comes to weight loss there isn’t one. I gained 70lbs in the last 4 years and finally realized how unhappy I was. 20 days in and I have lost 14lbs/6kg. I am strict on my diet, though to be honest haven’t done the recommended exercise. So I can only imagine how much I would have lost in that time. As for the oily orange stools, I haven’t had any uncontrollable accidents, you can see it in the toilet bowl but haven’t had any embarrassing moments as of yet, but I am keeping within the recommended daily allowance of fats. I would recommend Orlistat to anyone who needs a helping hand, I have found that it has made me really determined to make better choices regarding my health and weight. Co-workers and family have noticed a difference in my body and I can feel it in my clothes so I’m really happy."
Many praise its effectiveness, while some report common side effects like diarrhoea, upset stomach, gas, and headaches
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Up to 10% weight loss
Works by blocking around 30% of dietary fat absorption, making unabsorbed fat pass through your system
Clinical trials show that, when combined with a reduced‑calorie diet and exercise, Xenical users lost approximately 5-10% of body weight over 12 months.
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Costs approximately £59-£79 for 84 capsules.
Orlistat 120mg (Generic)
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Orlistat is a clinically approved weight loss tablet that works by blocking fat absorption in the body. It’s most effective when combined with expert medical guidance and a healthy lifestyle, helping you lose weight safely and sustainably.
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385 reviews with an average rating of 7.4 ³
64% of reviewers report a positive experience, only 17% report negative
Broadly positive feedback:
"Been using this medication for a little over a week. My observations are the following: 1. Do not fart unless you are on a toilet. Unless you don’t mind the orange skid marks. 2. Keep a toilet brush handy to clean your bowl after you flush your gross stool. Unless you don’t mind a dirty toilet. 3. Again, hold those farts in until you find a toilet. Just avoid being around people smoking unless you want to cause a fire from the gasses you release."
Commonly mentioned side effects include diarrhoea, gas, upset stomach, constipation, and bloating
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Up to 10% weight loss
Blocks around 30% of fat absorption from your diet, helping to reduce overall calorie intake.
Clinical studies show that with a reduced-calorie diet and regular exercise, Orlistat users typically lose 5-10% of their body weight over 12 months.
Results are most effective when combined with lifestyle changes, including a low-fat diet to minimise side effects and support steady weight loss.
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Typically £34-£54 for a pack of 84 capsules (this can last 1-2 month supply).
Safety checklist before you start weight loss pilss
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Reduce fat in every meal
Aim for less than 15g of fat per meal to reduce side effects.
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Consider a multivitamin
Orlistat may lower vitamins A, D, E, K - take a multivitamin to replace them.
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Watch your bowels
Oily leaks suggest too much fat in your meal - try adjusting your diet.
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Stop if in pain
Severe stomach pain or dark urine needs urgent GP or 111 advice.
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Report side effects
Use the MHRA Yellow Card or speak with your pharmacist.
Best weight loss pills FAQs
Is Xenical stronger than Alli?
Yes. Xenical is the 120mg prescription version of orlistat, while Alli is a 60mg over the counter version. Both block fat, but Xenical stops more, so you may see faster results but also experience more side-effects.
Can I switch from Alli to Xenical?
You can, but only after a GP or pharmacist checks your BMI, liver health and diet. They’ll write a prescription if Xenical is safe for you.
What diet should I follow on orlistat?
Keep each meal under 15g of fat. Fill half your plate with veg, add lean protein, pick complex, whole-grain carbs, and spread calories over three meals. High-fat treats lead to oily stools - think of that as feedback to cut back on the amount of far you have in your meals.
What is the best over-the-counter weight loss pill?
Alli (60mg orlistat) is the only OTC medicine with NHS-recognised evidence. Herbal “fat burners” sold online are not backed by UK trials and can be unsafe, says the MHRA.
What is the top-rated prescription weight loss pill?
Xenical scores the highest user rating (8.2/10) on Drugs.com. Injectable GLP-1 medication report greater weight loss but involve needles, not pills.
Use these ratings only as background - your GP, pharmacist or obesity specialist is the best person to confirm which treatment suits your health and goals.
What is the best female weight loss pill?
No tablet is “best” just for women. The NHS uses the same orlistat criteria for all adults. Future GLP-1 pills in trials include both men and women, but none are licensed yet.
What is the best contraceptive pill for weight loss?
There isn’t one. The Faculty of Sexual & Reproductive Healthcare (FSRH) says modern contraceptive pills do not cause meaningful weight gain or loss - any small change is usually temporary. You should choose birth control for pregnancy protection, not weight loss.
What is the best menopause weight loss pill?
No pill is licensed just for menopause weight. The British Menopause Society advises a balanced diet, strength exercise and, if BMI is high, discussing orlistat or GLP-1 options with a GP.
Medically reviewed by Dr Jackir Hussain
This page was last medically reviewed by Dr Jackir Hussain on 14 July 2025.
At Pill Scout, we prioritise accurate, evidence-based health information you can trust.
Our medical team regularly reviews and updates our content to ensure it stays aligned with the latest clinical research and guidance.
Dr Jackir Hussain, MBChB, MRCGP
GMC: 7074207
Dr Jackir Hussain is a UK-based GP with over 14 years of clinical experience since earning his medical degree from the University of Manchester. He has worked across diverse healthcare environments, including NHS GP surgeries, urgent care services, homeless shelters, and telemedicine platforms.
His areas of interest include general practice, weight loss, and the use of digital health to improve patient access to care.
Sources
¹ Based on Alli User Reviews - Drugs.com. Accessed 2nd July, 2025.² Based on Xenical User Reviews - Drugs.com. Accessed 2nd July, 2025.
³ Based on Orlistat User Reviews - Drugs.com. Accessed 2nd July, 2025.
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