Orlistat
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FDA approved 19991 clinical trial reviewed

Orlistat

Xenical

A capsule that blocks about a third of the fat you eat from being absorbed

In short

Orlistat (Alli / Xenical) works differently from other weight loss drugs — it blocks about a third of dietary fat from being absorbed. Average weight loss in trials was about 5.7%–8.5%.

8.5%

average weight loss in clinical trials (1-year RCT (Rissanen 1998))

That's ~19 lbs for a 220 lb person

Key facts

At a glance

The numbers you need before deciding.

Weight loss
6.9%

~15 lbs for a 220 lb person

Monthly cost
$40–$400/mo

OTC version (Alli 60mg): ~$40–$60/month, no prescription needed

How you take it
Capsule 3× daily with meals

With each fat-containing meal — no injection

Main side effect
Oily stools

About 3 in 10 people

Fat vs lean
Limited data

Body composition breakdown not yet published

If you stop
Weight regain expected

Pattern consistent with the drug class

Before you start

Learn about this treatment

Everything you'd want to know before deciding.

Weight loss results
Trial data, timelines, what's realistic
Side effects
Rates, what helps, and when to call your doctor
Cost & savings
List price, insurance, manufacturer programs
How it works & dosage
Lipase inhibitor — what that means for you
Clinical evidence
1 trials, all linked

On treatment

Already taking this?

Practical guides for people currently on this medication.

Dose titration schedule
Step-by-step dose increases
Not losing weight yet?
Troubleshooting — what to check first
Nausea or GI issues
What helps right now — from trial data
Missed a dose
When to take it, when to skip
What to eat
Protein targets, meal timing, appetite shifts
Week-by-week journey
What to expect from week 1 to month 12

Clinical evidence

How it compares in trials

Average weight loss % — from individual phase 3 trials

Orlistat
8.5%
Semaglutide injection
14.9%
Tirzepatide
20.9%

Lower average weight loss than newer medications, but available without a prescription in lower-dose OTC form (Alli 60mg).

Affordability

Cost & savings

$40–$400per month

Savings options

OTC version (Alli 60mg): ~$40–$60/month, no prescription needed. Prescription Xenical (120mg): ~$200–$400/month.

Is this right for you?

Who this tends to fit

Relevant if you

  • Want the only non-prescription option (Alli OTC)
  • Prefer a non-hormonal approach that works in the gut, not the brain
  • Want the most affordable OTC option

Not right if you

  • You eat a high-fat diet and are not willing to change it
  • You have chronic malabsorption or bile flow problems
  • You want significant weight loss

Safety

Important cautions

  • Rare cases of severe liver injury have been reported with orlistat. Tell your doctor immediately if you notice yellowing skin or eyes, dark urine, or itching.

  • Orlistat reduces absorption of fat-soluble vitamins (A, D, E, K). Take a daily multivitamin — at bedtime, at least 2 hours away from your orlistat dose.

  • Orlistat may reduce the absorption of some medications. Tell your doctor and pharmacist about all other medications you take.

Practical guide

How to take Orlistat

1

Take one capsule three times daily — during each main meal that contains fat, or up to 1 hour after

2

If you skip a meal or eat a fat-free meal, skip that dose

3

Take a daily multivitamin at bedtime — at least 2 hours away from your orlistat doses

4

Stored at room temperature. No refrigeration needed.

Common questions

FAQ

Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment.