The Independent Pharmacy

Alli (Xenical) Vs Orlistat: Which Is Better For Weight Loss?

Scott McDougall
Scott McDougallMPharmDirector & Registered Manager

Reviewed on 30 Nov 2023

When exploring weight loss options, you may come across the medications Alli, Orlistat, and Xenical. Understanding the differences between these three drugs is key to determining which one may be right for your weight loss goals.

Alli 60mg Capsules
Alli 60mg Capsules
View Weight Loss Treatment

At a basic level, Alli is an over-the-counter option, while Orlistat and Xenical are prescription medications. However, there are more intricate differences when it comes to their chemical composition, dosage, side effects and more.

Orlistat 120mg Capsules
Orlistat 120mg Capsules
View Weight Loss Treatment

In this guide, we'll help you understand how the medications differ from each other and how they could help you on your weight loss journey.

By the end, you will understand the unique positioning of Alli vs Xenical and Orlistat for personalised weight loss support and make the right choice for you.

Key Takeaways:

  • Alli, Xenical, and Orlistat all use the fat-blocking drug orlistat to stop your body from soaking up fat and calories from foods, but at different amounts (Alli 60mg, Xenical/Orlistat 120mg)
  • Easy-to-get, over-the-counter Alli assists in moderate weight loss for generally healthy overweight people by mildly preventing fat absorption
  • Prescription Xenical and Orlistat greatly boost blocked fat and calorie passing through your system for considerably increased weight loss backed by medical studies showing double Alli's fat reductions
  • No “one size fits all” weight loss solution exists; talk to your doctor to decide if adding prescription pill support fits your situation and goals as part of an all-around lifestyle change plan

Alli vs. Orlistat vs. Xenical: At a Glance

AvailabilityOver-the-counterPrescription only;
available through
NHS if criteria met
Prescription only;
available through
NHS if criteria met
Dosage of
Intended UseMild weight
loss for slightly
overweight adults
Clinically obese
patients or
those with
health risks
Clinically obese
patients or those
with obesity-related
health risks
Fat Absorption
About 25%About 30%About 30%
Side EffectsMild stomach
issues like
oily stools
More frequent
or intense
issues due to
higher dosage
More frequent
or intense stomach
issues due to higher
CostGenerally less
More expensive
than Alli; cost
varies; may be
covered by NHS
Branded, typically
more expensive than
generic Orlistat; may
be covered by NHS
Suitable for adults
making lifestyle
changes for
moderate weight loss
Requires medical
supervision, especially
for those with
related health risks
like type 2 diabetes
Same as Orlistat,
with the added
brand recognition
of Xenical

Comparing Alli, Orlistat and Xenical

How Do These Medications Work?

When it comes to how Alli, Xenical and Orlistat actually work, they share a common mechanism despite having different purposes and dosages.

You see, all three weight loss aids contain some amount of the active ingredient orlistat. This is the special component that prevents your body from absorbing about 25-30% of fat from the foods you eat. It works by blocking particular enzymes and proteins that would normally help digest dietary fat and break it down for absorption.

Alli has a smaller amount of orlistat (60mg), so it blocks about 25% of the fat you eat. This unabsorbed fat leaves your body naturally, but it can cause some uncomfortable side effects like oily stools.

Now, Xenical and prescription Orlistat have a bigger punch with 120mg orlistat per capsule. Take one of these capsules during a high-fat meal, and it’ll block closer to 30% of the fat you consume from getting absorbed compared to Alli. More undigested fat passing through can really accelerate weight loss results.

So, in the end:

  • All three medications use orlistat to block some fat from getting absorbed
  • But Xenical and Orlistat’s stronger 120mg dose blocks MORE fat for enhanced weight loss effects

Who Are These Medications for?

As an over-the-counter option, Alli can be purchased without a prescription and is intended for overweight adults looking to lose a moderate amount of body weight through changes in a healthy diet and exercise regime. With lighter fat absorption blocking effects, Alli usage guidance positions it for individuals seeking to lose those last few stubborn pounds.

Xenical and Orlistat are stronger at blocking fat because they have a higher dose of orlistat (120mg) in each capsule. As such, these prescription-only weight loss medications should be used under the close care of a physician, especially for clinically obese patients needing major weight loss interventions and support. Overweight patients managing related health risks like type 2 diabetes, high blood pressure or heart disease may also benefit from their enhanced weight reduction.

In plain terms:

  • Alli assists slightly overweight folks through mild fat reduction
  • Xenical & Orlistat target the obese with higher doses for substantial fat malabsorption

Accessing the Medication

As an over-the-counter medication, Alli is widely accessible without requiring a prescription. It can be conveniently purchased at local pharmacies, superstores, and online retailers. This makes it easy to obtain for adults seeking supplemental weight loss aid.

Meanwhile, Xenical and Orlistat are only available by prescription. Obese patients and overweight individuals managing additional health risks need to schedule an appointment with their doctor or weight loss clinic to be evaluated for candidacy. If deemed an appropriate fit, patients can get a prescription to acquire Xenical/Orlistat through traditional pharmacies or online telehealth platforms.

So, while Alli's over-the-counter status makes it easily accessible, acquiring Xenical or Orlistat involves prescriptions and physician consultations, given their higher potency.

Side Effects

As orlistat-containing products designed to inhibit dietary fat absorption, Alli, Xenical and Orlistat can all potentially cause similar stomach side effects. Common stomach-related symptoms may include:

  • Oily spotting
  • Flatulence with an oily discharge.
  • Fatty or oily stool.
  • Greater frequency of bowel movements.
  • Requiring an urgent bowel movement.
  • Inability to control bowel movements.

However, because Xenical and Orlistat have a higher dosage (120mg), they can cause more frequent or severe stomach issues, like uncontrolled bowel movements, compared to the lower dose found in Alli. Staying hydrated and being mindful of dietary fat intake can be helpful strategies in managing side effects. Remember, your well-being is paramount, and it's okay to reach out for support if you're experiencing discomfort. Seeking medical assistance for prolonged, bloody or concerning diarrhoea is recommended for all orlistat products.

Effectiveness and Clinical Evidence

Alli’s Mild Fat-Blocking Results

With a lower 60mg dose of orlistat, Alli provides milder fat absorption-blocking effects compared to the prescription options. However, extensive research shows these effects adequately assist overweight folks wanting to lose some pounds by cutting fat in their diet and exercising regularly. On average, people start seeing gradual fat reduction within weeks.

Xenical and Orlistat's Robust Fat Blocking and Weight Loss

Multiple robust clinical trials have proven much better weight loss results with Xenical and prescription 120mg Orlistat versus over-the-counter alternatives:

In one 2-year study, patients taking the highest 120mg Orlistat dose lost nearly 10% of their starting body weight on average in one year—way higher fat reduction than the 60mg group at just 8.6%. Participants in both medication groups kept losing for a while after stopping treatment, but the 120mg dose maintained bigger weight loss long-term.

Showing how well Xenical works, another multi-year trial added Xenical or only dietary changes for obesity treatment. After one year, the Xenical group lost more dangerous belly fat surrounding organs versus just changing their diet.

So while accessible Alli promotes modest outcomes, Xenical and prescription Orlistat’s maximum-strength doses drive way upped fat and calorie malabsorption for substantially boosted weight loss per rigorous medical studies.

The Unique Position of Alli in Weight Loss

Understanding that each person's journey to health is unique, Alli provides a readily accessible option without the need for a prescription, offering a supportive step for those beginning their weight loss journey. Unlike Xenical and prescription-only Orlistat, which requires doctor visits for approval, Alli eliminates barriers to medical weight loss interventions.

Additionally, the ability to discreetly purchase Alli without consultations appeals to consumers who feel embarrassed about needing weight loss treatment. Recognising the personal nature of weight loss, Alli's over-the-counter availability allows individuals to embark on their journey privately, supporting their efforts to make positive dietary and lifestyle changes at their own pace.

Special Considerations for Alli Users

Individuals living with chronic conditions that affect nutrient absorption or digestion should exercise caution with Alli. These drugs not only block fat but can also reduce the absorption of some important nutrients like vitamins A, D, E, K, and omega-3 fatty acids. Thus, long-term Alli users may benefit from supplementation to prevent vitamin A, D, E and K deficiencies, as well as maintain healthy levels of essential fatty acids.

Success with weight loss treatments

In order for Xenical or Orlistat to be successful, you will need to combine your course of medication with a sensible and low-calorie diet, as well as exercise regularly. If you do this, it is possible to lose an average of 10% of your body weight after one year.

Alli, Xenical or Orlistat: Making the Right Choice

Choosing the right weight loss medication comes down to considering individual factors like current health status, amount of weight to lose, and accessibility constraints.

For individuals striving to lose a few pounds, the easily accessible over-the-counter option, Alli, might offer a supportive and convenient starting point in their journey towards better health. It's important for individuals with underlying digestive conditions to approach Alli with care, and it may be advisable to explore other options in close consultation with a healthcare provider.

On the other hand, the prescription power of Xenical or Orlistat proves more impactful for those clinically classified as obese and need extensive interventions. Their high doses spur considerable fat and calorie malabsorption for accelerated body shaping and weight reduction.

Ultimately, there is no “one size fits all” solution. Consult a doctor or weight loss specialist to make the most personalised medication decision tailored to your health profile and goals. An integrated plan including dietary changes, exercise adoption, and possible medication support grants the highest likelihood of sustainable success.

Taking a Holistic Approach

While adding medications can augment weight loss results, achieving and sustaining significant fat reduction requires comprehensive lifestyle changes. Adjusting eating habits, activity levels, and other behaviours support these drugs’ effectiveness.

Orlistat products prevent some fat absorption, they cannot override other poor dietary choices or lack of physical activity. Prescription pills aren’t “magic”; they complement other evidence-based weight loss interventions. Patients seeing the best results incorporate weight management medications into a holistic wellness plan, also prioritising healthy nutrition and regular exercise for amplified and lasting benefits.

Take the Next Step with The Independent Pharmacy

Deciding whether over-the-counter Alli versus prescription Xenical or Orlistat fits your weight loss goals requires understanding key differences in potency, suitability, side effects, availability and proven results.

Once you determine the best fit based on your health profile, risk factors and amount of weight loss desired, the next step is a consultation about integrating supportive medication alongside adjusting nutrition, activity levels, and other lifestyle behaviours for sustainable success. Comprehensive wellness changes ensure you not only lose fat but keep it off long-term.

The Independent Pharmacy can help you to kickstart your weight loss journey today. All you need to do is fill in your self-assessment, and one of our experts will get in touch with treatments suitable for your situation. Worried about embarrassment seeing your local pharmacist? Have medications discreetly delivered instead. Or simply start your health journey with science-backed advice from compassionate specialists.

Reach out to The Independent Pharmacy today to fill in your assessment at no obligation. Our sole focus is arming patients with weight management resources to confidently get results, feel healthier and reduce future disease risks—no judgement or guilt trips. Let us help guide your personalised path toward sustainable fat reduction and a better quality of life on your own terms.


Is Alli as Good as Xenical?

While Alli and Xenical share the same active ingredient, Xenical contains twice the amount of orlistat (120mg vs 60mg) and is only available by prescription. So no, over-the-counter Alli is not as potent or effective as prescription-strength Xenical when it comes to blocking dietary fat absorption and assisting weight loss. But Alli can be easily obtained for mild-to-moderate fat reduction.

Does Alli Help with Belly Fat?

Alli can help reduce overall body fat, including dangerous visceral belly fat, with long-term use alongside diet and exercise changes. However, it does not specifically or exclusively target abdominal fat. For substantial belly fat reduction, the prescription Xenical and Orlistat formulations may prove more effective.

How Fast Will I Lose Weight on Alli?

Individual results vary, but on average, most people begin noticing gradual fat reduction and weight loss within a few weeks of beginning Alli treatment, also coupled with a reduced-calorie diet and consistent exercise regime. Typically, the first few months see the most dramatic drops as the body adjusts.

What Is the Most Successful Weight Loss Pill?

Based on clinical evidence, prescription medications Xenical (orlistat 120mg) and Orlistat have demonstrated the highest rates of significant weight loss and fat absorption reduction. But lifestyle factors remain key - the most “successful” solutions combine pharmacological support with healthy nutrition and regular physical activity.

Who Should Not Use Alli?

Groups who should avoid Alli include pregnant or breastfeeding women, people with chronic malabsorption syndrome or long-term pancreatitis, and those taking other medications that may interact, like cyclosporine and levothyroxine. Having an active irregular heartbeat, heart disease, kidney or liver problems are also contraindications for using Alli.


Obesity - NHS (

Obesity - Treatment - NHS (

Facts about fat - NHS (

all-weeks.pdf (

Related Guides

Need something else?

We stock 1052 treatments for 90 conditions

Or browse all treatments or conditions

A customer at the pharmacist looking for medication