If people with intolerance to fructose take sorbitol, it can lead to stomach upset and diarrhoea. Tegretol liquid contains parahydroxybenzoates which may cause allergic reactions. View detailed reports from patients taking tegretol who experienced dyspepsia. Reports are from official medical reports as well as online extractions from user reviews and forum discussions. Signs of a pancreas problem (pancreatitis) like very bad stomach pain, very bad back pain, or very bad upset stomach or throwing up. Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain. Summary. Stomach upset is found among people who take Tegretol, especially for people who are female, 60+ old , have been taking the drug for 1 month, also take medication Neurontin, and have Pain. Doctors give unbiased, trusted information on whether Tegretol can cause or treat Indigestion: Dr. Fowler on stomach upset from carbamazepine: Common side effects include dizziness, sleepiness, headache, swelling of the extremities, and diarrhea. Drug interactions are possible too. Sounds like a call to your doctor is in order. Tegretol (carbamazepine) is an anticonvulsant used to treat seizures and nerve pain such as trigeminal neuralgia and diabetic neuropathy. Tegretol is also used to treat bipolar disorder. Tegretol (Carbamazepine) is an anticonvulsant and mood stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder.migraines, motor coordination impairment and/or upset stomach. I am on tegretol and gabapentin it makes me dopey but I still have the pain. I take 2 tegretol and 6 600mg. gab. I have been taking for 5 days. Does anyone know when relief will come. Tegretol (carbamazepine) is an anticonvulsant. It works by decreasing nerve impulses that cause seizures and pain. Tegretol is used to treat certain types of seizures (partial, tonic-clonic, mixed). Upset stomach is found among people who take Tegretol, especially for people who are female, 60+ old , have been taking the drug for 1 month, also take medication Neurontin, and have Pain.