Over-the-counter weight loss pills

Everything you need to know about the only clinically-proven over-the-counter weight loss pill sold in the UK.

What is an over-the-counter weight loss pill?

An over-the-counter (OTC) pill is sold without a doctor’s prescription, but still under a pharmacist’s advice. In the UK only one slimming tablet meets that rule - Alli 60mg. Stronger weight loss tablets like Xenical need a prescription.

Who can buy Alli in a pharmacy?

You can buy Alli over-the-counter if you:

  • Are 18 years or older¹

  • Are overweight with a BMI ≥ 28

However, you’ll need to speak to a pharmacist first and answer a quick questionnaire about your medical history and allergies.

You can’t take Alli if you’re pregnant, breastfeeding, or taking ciclosporin.²

The only OTC weight loss pill in the UK

Alli (Orlistat 60mg)

Active ingredient. Orlistat, but half the strength compared with prescription medication Xenical.

How it works. Blocks an enzyme called lipase so some of the fat you eat passes straight through your gut without being absorbed.

Dose. One 60mg capsule with each meal that contains fat, up to three tablets a day.

Effectiveness. Alli is considered a modestly effective weight loss aid. Clinical studies show that people taking Alli typically lose around 2.5kg (5.5 pounds) more over 12 months than those using diet and exercise alone. ³ While results vary, the difference is clinically meaningful for many users.

Common side-effects and quick fixes

  • Oily / fatty stools

    This happens because fat leaves your gut unabsorbed. To help, keep each meal below 15g of fat.

  • Orange spotting

    Unabsorbed fat can leak. Wearing dark underwear and carrying a spare pair keeps things discreet.

  • Toilet urgency

    Lower the fat in each meal, spread food across the day and stay near a toilet until side-effects ease.

  • Mild cramps

    Your gut is adjusting to reduced fat absorption. Cut fried foods to settle the discomfort.

  • Low vitamins

    Take a multivitamin at bedtime with vitamins A, D, E and K to help keep levels healthy.

OTC weight loss pills FAQs

Do I need a prescription to buy Alli?

No. Alli is classed as an over-the-counter medicine (category P), so you can buy it without a GP prescription, but the pharmacist will ask a few health questions and check your BMI is at least 28.

Is Alli safe for teenagers?

Alli is licensed only for adults aged 18 and over. Teenagers should see their GP or a specialist clinic instead.

Will Alli work without changing my diet?

It helps a bit, but trials show you lose far more weight when you follow a low-fat diet. High-fat meals trigger oily leaks and cancel the benefit.

How do I get the best results with Alli?

  1. Limit every meal to ≤ 15g fat.

  2. Spread calories over three meals (skipping meals can cause side-effects at the next one).

  3. Add daily movement (walking, cycling, swimming, etc).

  4. Take a multivitamin at bedtime to replace vitamins A, D, E and K lost in your stool.

How much do over-the-counter weight loss pills cost?

UK pharmacies sell an 84-capsule starter pack of Alli for about £29-£49 (usually this supply lasts four weeks).

When are OTC weight loss pills not enough?

You may consider other weight loss medication if:

  • Your BMI is 30 or higher and lifestyle efforts haven’t worked.

  • You have weight-related health conditions such as type-2 diabetes or sleep apnoea.

  • After three months on Alli you haven’t lost at least 5% of your starting weight.

At that point, you may consider booking a GP appointment to discuss prescription weight loss pills, injectable GLP-1 medicines, or referral to an NHS weight management service.

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 Alli. Is alli right for me? Last accessed July 2025.

² EMC database. Summary of product characteristics and contraindications for alli 60 mg hard capsules. Last updated April 2023.

³ Healthline. Do Alli weight loss pills (Orlistat) work? An evidence‑based review. Last updated June 2022.

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