How do I reduce the embarrassing side effects?

Follow a reduced-fat diet — keep each meal to under about 15g of fat. The oily stools, urgency, and spotting are directly caused by unabsorbed fat passing through your system. Less fat in means fewer side effects. Most people who experience severe side effects are eating too much fat.

Do I need a prescription?

For the 120mg prescription-strength version (Xenical), yes. The 60mg lower-dose version (Alli) is available over the counter from pharmacies without a prescription — no doctor's visit required.

Do I need to take vitamins?

Yes — orlistat reduces the absorption of fat-soluble vitamins A, D, E, and K. Take a multivitamin daily, ideally at bedtime (at least 2 hours away from your orlistat doses) so the vitamins can be absorbed properly.

How does it compare to the newer drugs?

Orlistat produces more modest weight loss — trials show about 3–6% of body weight on average, versus 8–21% for the newer GLP-1 drugs. But it is the only weight loss drug available without a prescription, has a 4-year safety record (XENDOS trial), and works entirely in the gut with no effects on the brain.

Xenical & Alli (Orlistat)

Key facts

At a glance

The numbers you need before deciding.

Weight loss

8.5%

~19 lbs for a 220 lb person

Monthly cost

$40–$400/mo

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

How you take it

3x 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

No body scan data published yet for this drug

If you stop

Weight regain expected

Same pattern as similar drugs

Before you start

Learn about this treatment

Everything you'd want to know before deciding.

Weight loss resultsTrial data, timelines, what's realistic Side effectsRates, what helps, and when to call your doctor Cost & savingsList price, insurance, manufacturer programs How it works & dosageFat blocker — dose levels and what that means for you

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Clinical evidence1 trial, all linked See every treatment on one pageWhere this drug sits alongside older medicines, devices, procedures and surgery

On treatment

Already taking this?

Practical guides for people currently on this medication.

Dose titration scheduleStep-by-step dose increases Not losing weight yet?Troubleshooting — what to check first Nausea or GI issuesWhat helps right now — from trial data Missed a doseWhen to take it, when to skip

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How to take itWhen, how, storage What to eatProtein targets, meal timing, appetite shifts Week-by-week journeyWhat to expect from week 1 to month 12

Compare

Side-by-side comparisons

See how this drug compares with another, side by side.

Zepbound vs XenicalFull side-by-side comparison Wegovy vs XenicalFull side-by-side comparison Foundayo vs XenicalFull side-by-side comparison Saxenda vs XenicalFull side-by-side comparison

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Qsymia vs XenicalFull side-by-side comparison Contrave vs XenicalFull side-by-side comparison

Clinical evidence

How it compares in trials

Average weight loss % — from individual phase 3 trials

Xenical / Alli8.5%

Wegovy (semaglutide injection)14.9%

Zepbound (tirzepatide)20.9%

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

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 a lower-cost, non-prescription 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.

See what the label says about pregnancy and breastfeeding.

Practical guide

How to take Xenical & Alli

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

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

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

Stored at room temperature. No refrigeration needed.

Common questions

FAQ

Questions to ask your doctor

→Am I a good candidate given my health history and any other conditions I have?
→Do I have any contraindications I should know about?
→What results should I realistically expect, and over what timeframe?
→Which side effects should make me contact you?
→How long should I try this before we decide if it's working?
→What happens if I need to stop — how do I come off it safely?

Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice

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Compare all optionsSee how this stacks up against other treatments Am I eligible?Check if this type of medication is right for you Talk to your doctorWhat to bring up at your next appointment Side effects comparedHow side effects differ across all treatments

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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. Prices shown are United States self-pay or list prices and vary by insurance and country.