As with any medicine, it is possible that you will experience some side effects whilst using Xenical.
Most unwanted side effects will be related to your digestive system, tend to be very mild and occur mainly at the beginning of your treatment or if you eat a meal containing high levels of fat. Changes in your bowel movements, like an increase in oily or fatty stools, are mostly harmless and occur because your body is working to expel undigested fat. These symptoms should disappear if you continue your regular treatment and stick to the recommended low-calorie diet.
Some common side effects (affecting more than 1 in 10 users) include:
- Changes in your stools (softer, looser, more oily)
- Pain or discomfort in the rectum
- Bloating and stomach pain
- An irregular menstrual cycle
- Tooth or gum disorders
Always tell your prescribing nurse, doctor or pharmacist immediately if you ever start to feel unwell or any your symptoms worsen as a result of using Xenical.
Signs of an allergic reaction include:
- Itching, rashes or blistering of the skin
- Breathing problems
- Vomiting or nausea
- Bloody stools or bleeding from the rectum
If you ever experience any side effects that are not listed in this page, you can report them using the Yellow Card Scheme to help provide more information on the safe and proper use of this medicine: https://yellowcard.mhra.gov.uk/.
Are there any safety precautions to be aware of while using it?
If you are currently on any other form of medication, make sure to inform your nurse, pharmacist or doctor before taking Xenical. In general, losing weight can mean you will have to adjust the dosage of your other medications.
Taking Xenical can modify the activity of:
- Medicines used in the treatment of HIV
- Anticoagulants, like warfarin
- Medicines for high cholesterol or diabetes
- Iodine salts and/or levothyroxine (in some cases, hypothyroidism, or reduced control of hypothyroidism can occur)
- Anticonvulsivant treatment for epilepsy (orlistat may decrease the absorption of antiepileptic drugs, leading to an increase in convulsions - contact your doctor if you think that the severity and/or frequency of your convulsions have changed whilst taking Xenical).
Xenical is not recommended for use by people who are also taking the anti-diabetic drug acarbose, used to treat diabetes mellitus (Type 2).
Xenical will also reduce the absorption of some important fat-soluble nutrients like beta-carotene and vitamin E. Talk to your doctor for advice about having a well-balanced nutritional diet whilst taking Xenical, and take multivitamin supplements if advised.
If you suffer from chronic kidney disease, orlistat can be associated with renal stones. Talk to your doctor before taking Xenical if you suffer from kidney problems.
There is no known effect on a user’s ability to drive or operate heavy machinery whilst on Xenical.
If you are sexually active and experience severe diarrhoea whilst using Xenical, it is recommended that you use condoms as an additional precaution to prevent the possible failure of oral contraceptives.
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