Report on Xenical Side Effect and Usage by AskDocWeb

About Xenical

Picture of Xenical     Xenical icture

What is Xenical?

Xenical is pronounced: zen’ i-cal. It’s the brand name of the drug orlistat (pronounced, OR lih stat), a white to off-white crystalline powder. It was approved by the FDA April 23, 1999.

Xenical is a weight-loss aid used to help people who fit certain weight and height requirements, lose weight and then maintain their weight. It comes in dark-blue, hard-gelatin capsules, with light-blue imprinting. Xenical is the first of a new class of anti-obesity drugs known as lipase inhibitors.

How does Xenical work?

When you eat fat, it’s broken down by enzymes called lipases so that your body can absorbed it. Xenical interferes with the activity of these enzymes temporarily, which blocks some of the fat you eat from being absorbed. This allows about 30% of the fat eaten to pass through the body undigested.

Xenical works only in the digestive system. It does NOT change your appetite. It blocks absorption of dietary fat into the bloodstream, thereby reducing the number of calories you get from a meal. At the usual dosage level, it cuts fat absorption by almost one-third.

Xenical decreases the absorption of some fat-soluble vitamins and beta-carotene. To compensate, you should take beta-carotene and a multivitamin with vitamins A, E, D, and K once a day, at least 2 hours before or 2 hours after taking Xenical. Use it with a reduced-calorie diet your doctor will recommend.

What side effects do users of Xenical report?

Normally, side effects disappear if you continue treatment and keep to your recommended diet. Don’t be alarmed by this list of side effects. You may not experience any of them. Most patients experienced only one episode. Consult with your doctor on any side effects that are of concern to you.

Abdominal discomfort or pain



Back pain

Diarrhea, generally mild and goes away




Fatty or oily stools – 20% of patients

Fecal urgency or incontinence – 22.1% of patients


Gas with fecal discharge, generally mild and goes away – 23.9% of patients

Gum problems


Increased defecation

Incontinence (fecal) – 7.7% of patients

leaky stools in some patients temporarily

Menstrual problems

Muscle pain


Rectal discomfort or pain

Respiratory tract infections

Skin rash

Sleep problems

Stomach cramps

Tooth problems

Urgency to have a bowel movement

Urinary tract infections

Vaginal inflammation


Less common side effects may include dry skin, ear/nose/throat problems and joint disorders.

Side effects that usually occur after the first year of treatment with Xenical include depression, leg pain, swollen feet and tendonitis.

Due to the presence of undigested fat, it’s natural for the bowel movement to change color. It may be clear to orange or brown. These bowel changes are a natural effect of blocking the fat from being absorbed and indicate that xenical is working.

There’s an unpleasant cost of going off your diet. Side effects are worse with more fat. The more fat you eat, the more side effects you can suffer. Keep to your recommended diet of meals containing no more than 30% fat.

What are the symptoms of overdose or something gone wrong?

Symptoms of an overdose are not known because none have been reported. Studies have been done on doses up to 240 mg for 6 months without significant increase of adverse findings.

Single doses up to 800 mg Xenical and multiple doses of up to 400 mg three times a day have been studied without significant adverse effects.

If you think you have overdosed, call your doctor for advice or go to Emergency at your nearest hospital. Even if there’s no sign of discomfort or poisoning. You may need urgent medical attention. Keep those telephone numbers handy.

A rare allergic reaction may including shortness of breath; closing of your throat; swelling of your lips, tongue, or face; or hives.

If you miss a dose of Xenical

You can take the missed dose up to one hour after a meal. If more than one hour since your last meal, skip the dose and take the next regularly scheduled one as directed. Don’t take a double dose of this medication.

If you miss a meal, or if you have a meal without fat, you can skip your dose of orlistat for that meal also.

If you have missed several doses, tell your doctor and follow his advice.

Conditions you should tell your Doctor about before taking Xenical:


Chronic malabsorption syndrome
Gallbladder problems
You may not be able to take orlistat if you have one of the above conditions.

Anorexia or bulimia
History of kidney stones
Plan on getting pregnant
Pregnant or breastfeeding a child

Tell Your Doctor if you’re taking any of the following medicines:

Any other prescription drug
Atorvastatin (Lipitor)
Cerivastatin (Baycol)
Cyclosporine (Sandimmune, Neoral)
Fluvastatin (Lescol)
Lovastatin (Mevacor)
Pravastatin (Pravachol)
Simvastatin (Zocor)
Warfarin (Coumadin)
Any other dietary supplements, including herbal ones.

You dosage may require adjustment or special monitoring may be used if you’re taking cholesterol-lowering medicines.

Tell your doctor if you have allergies to any other substances, such as foods, preservatives or dyes, or if you have any other health problems.

Storing Xenical

Store at room temperature, away from heat and light, in a tightly sealed container, away from children. Xenical should not be used after the expiration date.

General Notes

Make sure your obesity does not have an organic cause like hypothyroidism, before taking Xenical.

Losing even small amounts of weight produces health benefits especially when you’re at risk for heart disease and diabetes.

Pooled data from 4 clinical studies indicate Xenical was just as effective in the second year as the first. Taking Xenical for more than 2 years has not been studied.

Xenical is not addictive and is available only with a doctor’s prescription. (See below)

On the average, patients lost 5 percent to 10 percent of their body weight, over one year.

Xenical should be used with a reduced-calorie diet with no more than 30% of calories from fat.

Don’t take more Xenical than has been prescribed for you. Taking larger doses has not shown any additional weight-loss benefit.

The effects of Xenical on your bowels are seen as soon as 24 hours after taking it.

The FDA put Xenical in the pregnancy category B. That means it isn’t expected to harm an unborn baby, but don’t take it without first talking to your doctor if you are pregnant.

You may hear your doctor talk about your BMI. That’s your body mass index: The body mass index (BMI) is the most widely accepted measurement of obesity. You can calculate your BMI
(or use our calculator) by dividing your weight in kilograms by your height in meters squared. Or if you don’t use metric, multiply your weight in pounds by 2.2 to get kilograms. Multiply your height in inches by 0.0254 to get your height in meters. Then it’s, height times height, divided into your weight in kilograms.

Xenical is indicated for obese patients with an initial BMI of 30 or greater. Make that 27 in the presence of high blood pressure, high cholesterol or diabetes.

Take each dose with a full glass of water.

In one study, 14119C, the people treated with a placebo regained 52% of the weight they had lost while people treated with Xenical regained only 26% of the weight they had lost.

Each time you take Xenical, your meal should contain no more than about 30% of calories from fat.

Abdominal pain may be worse if you continue eating a high fat diet or even eat a single high-fat meal.

Most patients stay on Xenical for about four months.

Xenical is twice as effective as dieting alone.

Alcohol does not affect Xenical.

Xenical significantly reduces weight among type 2 diabetics and improves long-term blood sugar control.

It is important to check with your doctor before combining Xenical with Cyclosporine or Warfarin.

Common Misspellings for Xenical

Xenical is often misspelled, as many people hear the word verbally, write it down and spell it incorrectly. Here are a few of the most common misspellings for Xenical: Xenicel, Zenical, Zenacal, Xinical, and Zanacal.

Xenical Feedback

If you’ve used Xenical, please help others by sharing your experience with side effects. What would you tell your best friend about this product? Please remember that we do not give medical advice. That is for your local health care provider, who is familiar with your medical history. You can use the form below to add your comments,
feedback or Xenical review.

Subj: Side effects
Date: 1/23/2003
Hi, I just thought I would let you know about my experience with Xenical.
I stopped taking it after 11 days due to the side effects. I had terrible trouble getting off to sleep at nights – I was lucky to get 5hrs. This is extremely unusual for me – I normally fall asleep as soon as my head hits the pillow. I also experienced a cold flushing feeling in my legs and fluid retention.

The Doctor said the fluid retention was propbably due to being overweight, but I believe it was worse (and still is) since taking this drug.

Luckily, I did not have any of the gastro side effects. I also felt my face was a red and blotchy face and I got a few a bit spotty – not good for a 32 year old. 2 days after stopping xenical, I was back to normal sleeping habits.

I reckon it’s safer to lose weight the healthy way and forget about these drugs.


Subj: xenical
I have been using XENICAL for about one year, and I have lost 40 pounds. But for the last 3 months there’s been no change in my weight (no gain, no loss). The only change I made in my diet 3 months ago, was that I started drinking Diet Coke. It may be stupid to ask, but is it possible that the “Aspartame” in the Coke reduce the efficiency of Xenical??


AskDocWeb: We haven’t found anything about Aspartame reducing the effectiveness of xenical, however, you could replace your Coke with water for a couple of weeks and find out what happens.

Subj: Xenical and Kidney problems
Date: 6/19/2003
I have been taking Xenical for about a month, and I have lost about 10 pounds. I have not had many of the common side affects, but last week I experienced my first kidney infection. It really worries me because my sister is on dialysis and another sister died of kidney failure. I went to my doctor about the kidney infection and she didn’t say anything about Xenical causing kidney problems, and in fact said to continue on the medications I am on. I would like to continue the Xenical because it works, but I am concerned. I have stopped taking it for now, but is there any way to know the infection was caused by Xenical? Thanks for any information you can give me.


AskDocWeb: We know that special concern is noted for people with a history of kidney stones but have no information about kidney infections being associated with Xenical.

Subj: feed back on Xenical
Date: 6/25/2003
I had failed at all sorts of weight loss programs … I figured I’d be 212 pounds (5′ 4″) forever. I was having problems with my blood pressure not being under control, and I found out I was developing diabetes. At 43 years old, this wasn’t the sort of life I wanted to have. My insurance didn’t cover Xenical (I “wasn’t obese enough”) so I had to pay $130/month for the medicine myself. Eight months later, I am 155 … and weaning off one of my blood pressure medications! I’ve gone from a size 22 to a 12 … and even wearing shorts again!

I feel like a new person! I can squat to the floor … and get back up! I can walk anywhere I want and not get short of breath or get leg cramps.

As for the side effects of Xenical, I was scared to use it. Many co-workers had failed on the drug because of the side effects. However, I felt this was my “last chance” at losing weight. I found that the side effects were controllable. It doesn’t take a rocket scientist to realize that if you eat a super size serving of french fries and a big mac sandwich and you take Xenical … that you’ll be blowing your brains out in the toilet! After making that mistake ONCE … you think twice before eating a meal high in fat.

Xenical is the ONLY thing that helped me … I am thankful for this medication … and urge other people to try it. You’ll love the results!


Subj: Xenical
Date: 9/17/2003
I lost 30 pounds in 3 months on xenical and a daily 20 minute walk. I have not had any side effects to speak of. As a busy Mom of four who loves to eat, this product has been fabulous. I still have my ‘fast food’ once a week – and balance out the rest of my day – I don’t feel deprived – I love this product!!! It is working for me.


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Most recent post: April 26, 2016

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