Alli is the less potent version of the prescription drug Xenical that contains the effective ingredient Orlistat. In 2011, the FDA highlighted the need for stronger warnings on the product labelling of Alli due to potential severe side effects. We ask just how safe is this product and should you be looking at safer, side effect free fat binder diet pills?

A popular diet pill on the shelves of UK stores, such as Boots and Lloyds Pharmacy and online. Let’s take a deeper and more in-depth look at it.

Alli Pros

  • Contains clinically proven ingredient

Alli Cons

  • Weight loss results modest at best
  • Unpleasant and potential serious side effects
  • Requires low fat diet to work
  • Expensive
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What You Need To Know About Alli

Alli is clinically proven to boost weight loss when added to a reduced calorie, lower fat diet. Alli is the only clinically proven, pharmacy-only weight loss aid medicine in the UK – it isn’t a miracle pill or quick-fix solution.

What Are The Side Effects Of Alli?

The most serious side effect concerns the cases of severe liver injury that have been reported with the use of this medication by the FDA.

How Much Does Alli Cost?

Alli costs £50 for a one month pack (84 capsules).

Our Verdict On Alli

By carefully following a low-fat diet and regular exercise programme, then this product may offer modest weight loss at best.

We can see no reason why any consumers would wish to suffer the unpleasant side effects that seem to have affected many consumers, and pay the high cost for what is such little weight loss.

Other clinically proven brands such as Proactol Plus and XLS Medical Fat Binder have less side effects reported by consumers and been shown to work, often cost less too!

For these reasons, we do not recommend Alli diet pills to our readers.

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Alli Review

Alli, pronounced “Ally”, was first launched in the US in June 2007 as the only Food and Drug Administration (FDA) approved weight loss aid available without prescription. Alli became available in 2009 in the UK when promoted as the lower strength over the counter version of the effective prescription drug, Xenical owned by Roche.

Alli Facts

  • Contains 60mg Orlistat compared to 120mg in Xenical prescription drug
  • Marketed by GlaxoSmithKline
  • Unpleasant side effects reported by consumers

Whereas Xenical contains 120mg of the active ingredient Orlistat, Alli contains half the dose of 60mg. It was allowed to be sold in licensed chemists under the guidelines that staff ensured anyone buying it was over 18 years old and had a Body Mass Index (BMI) of over 28. Source

There were a number of anecdotal reports from consumers and watchdog organisations that suggested the “only sell to consumers with a BMI of 28 or more” was largely not enforced.

Alli Concerns:

  • Diet pill that coined the phrase “Alli Oops” due to the unpleasant side effects!
  • Some UK retailers may have pulled the product off the shelves
  • Fairly expensive for what is very modest weight loss

Alli is marketed by GlaxoSmithKline (GSK) and in 2011 they were reported to be trying to sell this brand along with other over the counter weight loss products they owned. It’s been reported that they took this decision due to the poor performance of Alli sales and the wish to diversify. Source

Looking at the Official website now and it seems that GSK still own the brand.

What Does Alli Claim To Do?

It claims to…

For every 2 lb you work to lose through healthy eating, alli can help you lose 1 lb more…

It does this by…

alli works by blocking 25% of the fat you eat from being absorbed so makes your healthy choices even healthier.

Does Alli Work?

There are a number of studies supporting the use of Orlistat in the treatment for obesity. Clinical trials undertaken by GSK with Alli showed that…

when used in conjunction with a reduced calorie, lower-fat diet, can help people lose 50 per cent more weight than by dieting alone

Interestingly trials with Orlistat have given mixed results with the weight loss achieved, with one study showing on average a 5-10% decrease in body mass during a one-year clinical trial.

This same study showed a significant number of the subjects regaining up to 35% of weight after stopping taking Orlistat!

More information can be found here.

It would seem that Alli can trigger modest reductions in weight loss, although Orlistat can cause gastrointestinal side effects.

More information here.

What Are The Ingredients of Alli?

Alli belongs to the type of diet pills called Fat Binders that aims to reduce the amount of dietary fat absorbed in your meal. Studies have shown that up to 25% of the fat can be absorbed by blocking the enzymes that break down fats in the intestine. These undigested fats are then later removed from the body by the bowels.

There is only one active ingredient in this product, which is Orlistat the ingredient found in higher strength in the prescription only drug, Xenical. As the dose is half that seen in Xenical no medical supervision is required when taking it.

So, what is Orlistat?

  • Orlistat (60mg): Clinically proven to help weight loss although the results have been fairly modest. Possible unpleasant side effects experienced by consumers led to the phrase “Alli Oops”. Recently the FDA has reported concerns of the small number of consumers suffering from liver injury. Source

Alli is a non prescription, safer (although not side effect free, see below), over the counter versions of prescription drug Xenical.

When taken alongside a diet low in fat and regular exercise, this product can help in reducing calorie consumption by reducing the breakdown of some dietary fats in your meal.

Does Alli Have Any Side Effects?

The most concerning side effect concerns the cases of severe liver injury that have been reported with the use of this medication by the FDA.

Read the full FDA Report on Alli here

We should make clear that only 13 cases of severe liver injury have been reported worldwide between April 1999 and August 2009.

Other common side effects do occur though, the most common being consumers have reporting loose bowels when taking Alli, which has led to the phrase “Alli Oops”. These rather unpleasant side effects occurs because of the urgent bowel movements from having oily, loose stools that contain excessive fats! The need to frequently need the toilet has meant consumers have been confined to the bathroom!

When taking this, you are recommended to take a multivitamin with a meal because the supplement can reduce the levels of some essential fat-soluble vitamins.


Alli is not recommended for pregnant or nursing mothers, anyone taking warfarin or ciclosporin, and anyone allergic to Orlistat. In 2010 the FDA said that Alli should carry new warnings about the potential of severe liver injury.

Are There Any Customer Reviews For Alli?

There are mixed reviews from consumers who have tried it.

Some of positive reviews include…

Best product to aid a healthy eating plan for safe weight loss . Easy to take with each meal .I have tried many things on the market and Alli is the best .

In contrast negative reviews include…

This product worked in a way that it made me go to the toilet more often but it did not have any effect on weight loss overall!

Common themes amongst consumers with negative experiences are related to the need to frequently use the toilet. This was by all means not the experience for consumers taking Alli though.

Does Alli Offer a Money-Back Guarantee?

Alli does not provide for money back guarantee.

Where Can I Buy Alli?

Alli used to be one of the main weight loss brands promoted by High Street shops Boots and Lloyds Pharmacy, not to mention clearly visible on TV adverts day and night.

Anyone selling Alli are suppose to check the supplement is suitable by ensuring the Body Mass Index (BMI) is above 28. We have received reports that this rarely happens!

This product comes in various packs from 42, 84 and 120 tablets, as you take up to 3 tablets per day only the largest pack contains enough for one month’s supply.

How does Alli compare to Phentaslim?

Criteria Alli Comparison Phentaslim comparison
Clinically Proven Ingredients
Side Effect Free
Positive Customer Reviews
24/7 Support
Money-back Guarantee

The Diet Pills Watchdog does not recommend Alli.


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Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

Have Your Say

5 comments on 'Alli'

  1. 120mg in Xenica,ive used these for many years as due to arthritis in my spine it limits my mobility during winter due to lack of exercise i gain weight spring time onwards i can loose 2 stone no trouble but a low fat diet a must

  2. I was 190 in 2009. found out about Alli from a friend and started it with a low fat low calorie diet and by 2010 I was 160. Alli really works! But you must be careful of consuming too much fatty foods or you will have an oily stool when you use the bathroom or when you pass gas. But it works and I didnt have any bad side affects at all.

    1. Hi Lee, my name is Rose and I work for a TV production company called Little Gem. I would really like to talk to you about your Alli pill experience. If you are interested please email me at [email protected] Thank you

    1. Hi Mary,
      Products are sometimes changed and consumer feedback can vary overtime, not too mention that merchants also provide us with more information too. All these factors can affect our ratings and opinions on a particular supplement. Please get in touch and let us know specifics, or if you’re referring to this supplement then please elaborate more here.
      Kind regards,
      Diet Pills Watchdog Team

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