Like all medicines, this medicine can cause side effects, although not everybody experience it. Tell the doctor or pharmacist as soon as possible if the patient experiences any adverse effects during the treatment with Orlistat.
The majority of unwanted effects related to the use of Orlistat results from its local action in the digestive system. These symptoms are generally mild, occur at the beginning of treatment are particularly experienced after meals containing high levels of fat. Normally, these symptoms disappear if the patient continues treatment and keep the recommended diet.
Very common (may affect more than 1 in 10 people): headache, abdominal pain/discomfort, urgent or increased number of bowel movements flatulence (intestinal gas) with or without discharge, oily discharge, or fatty stool, liquid stools, low blood sugar levels (experienced by some people with type 2 diabetes), upper respiratory infections, flu (influenza).
Common (may affect up to 1 in 10 people): rectal pain/discomfort, soft stools, incontinence (stools), bloating (experienced by some people with type 2 diabetes), tooth/gum disorder, irregularity of menstrual cycle, tiredness, anxiety, lower respiratory infections, urinary tract infections.
Not known (frequency cannot be estimated from the available data): Allergic reactions: the main symptoms are itching, rash, wheals (slightly elevated, itchy skin, patches that are paler or redder than surrounding skin), severe difficulty in breathing, nausea, vomiting and feeling unwell. Contact the doctor immediately if the patient experience any of these.
Skin blistering (including blisters that burst).
Diverticulitis (inflammation of the small outpouchings along the wall of the colon).
Bleeding from the back passage (rectum).
Increased in the levels of some liver enzymes may be found in blood tests.
Hepatitis (inflammation of the liver): symptoms can include yellowing skin and eyes, itching, dark coloured urine, stomach pain, and liver tenderness (indicated by pain under the front of the rib cage on the right hand side), sometimes loss of appetite. Stop Orlistat if such symptoms occur and contact the doctor immediately.
Gallstones.
Pancreatitis.
Oxalate nephropathy (built up of calcium oxalate which may lead to kidney stones).
Effects on clotting with anticoagulants.