What is Alli?

Alli is a pharmacy-strength 60 mg orlistat capsule used for weight loss in adults aged 18 or over who are overweight (BMI ≥ 28 kg/m²).

It belongs to the class of medicines known as gastrointestinal lipase inhibitors and works in the digestive tract to block the enzymes that break down dietary fat. By preventing the absorption of around 25 % of the fat you eat, Alli helps reduce your calorie intake so more of the undigested fat is naturally excreted in the stool.
Alli can be purchased without a prescription in UK pharmacies, but a pharmacist must check it is safe and appropriate before supply.

What is Alli Used For?

Weight loss – for adults with a BMI ≥ 28 kg/m² who are following a calorie-controlled, lower-fat diet.
Improving weight-related health risks – losing weight can help lower blood pressure, improve cholesterol levels and support better blood-sugar control.

Note: Alli is not a quick fix. It works best as part of a comprehensive weight-management programme that includes a balanced, lower-fat diet and regular physical activity.

How Alli Works

Alli acts locally in the gut with minimal absorption into the bloodstream.

Blocks fat digestion: inhibits the gastrointestinal lipase enzymes so about a quarter of dietary fat is not broken down.
Fat excretion: the undigested fat passes out of the body in the stool, reducing overall calorie intake.

When is Alli Suitable?

You may be offered Alli if you:

Are 18 or older and have a BMI ≥ 28 kg/m².
Are committed to a reduced-calorie, lower-fat diet and regular exercise.
Have already tried lifestyle changes but need extra support to lose weight.
A pharmacist will confirm that Alli is appropriate for you before you start.

Can Alli Be Purchased Over the Counter?

Yes. Alli 60 mg is a pharmacy medicine (P-medicine) and is available without a prescription in the UK.
The higher-strength 120 mg orlistat (e.g. Xenical, Orlos 120 mg) is prescription-only.

Alternative Weight-Loss Medications

If Alli is not suitable, a prescriber may consider:

Prescription orlistat 120 mg (Xenical or Orlos) for BMI ≥ 30 kg/m² or ≥ 28 kg/m² with comorbidities.
GLP-1 injections such as Wegovy (semaglutide) or Mounjaro (Tirzepatide) for eligible patients.

How to Take Alli 60 mg

Dose: One 60 mg capsule up to three times a day with each main meal that contains fat.

Timing: Take during the meal or within one hour afterwards.

Meal composition: Spread your daily fat intake evenly and aim for meals containing about 15 g of fat.

Skip if no fat: If you miss a meal or eat a fat-free meal, skip that dose—do not double up.

Vitamins: Because Alli can reduce absorption of vitamins A, D, E and K, take a multivitamin at bedtime or at least two hours after your Alli dose.

Review: If you have not lost at least 5 % of your starting weight after 12 weeks, stop and consult your pharmacist or GP.

Diet & hydration: Continue a calorie-controlled, lower-fat diet and drink plenty of water.

Active ingredient: orlistat 60 mg.

Inactive ingredients (may vary by manufacturer): sodium starch glycolate, microcrystalline cellulose, povidone, talc.

The capsule shell contains gelatin and colouring agents.

Always read the patient information leaflet (PIL) in your pack for the complete list of ingredients, and to check for any you might be allergic to.

Common:

Oily or fatty stools
Urgent or more frequent bowel movements
Flatulence with discharge
Abdominal cramps or discomfort
Soft stools or rectal irritation
Occasional headache

These effects are more likely after high-fat meals and usually lessen as you follow a lower-fat diet.

Serious – seek urgent medical help (NHS 111 or A&E):

Severe abdominal pain (possible gallbladder or pancreatitis)
Signs of liver problems (yellow skin/eyes, dark urine, persistent fatigue)
Severe allergic reaction (swelling of face/lips/throat, difficulty breathing)
Rare kidney effects such as oxalate nephropathy