Cautions According To WebMD

Possible Side Effects:
Barberry can lower blood sugar so diabetics should use only under the supervision of their physician.

Possible Interactions:
B. vulgaris might decrease how fast the body breaks down cyclosporine (Neoral, Sandimmune). This might cause there to be too much cyclosporine (Neoral, Sandimmune) in the body and potentially cause side effects.

Barberry might decrease how quickly the liver breaks down some medications. Taking barberry along with some medications that are broken down by the liver might increase the effects and side effects of some medications. Before taking barberry, talk to your healthcare provider if you are taking any medications that are changed by the liver. Some medications changed by the liver include cyclosporin (Neoral, Sandimmune), lovastatin (Mevacor), clarithromycin (Biaxin), indinavir (Crixivan), sildenafil (Viagra), triazolam (Halcion), and many others.

Barberry might increase levels of certain chemicals in the body that work in the brain, heart, and elsewhere. Some drying medications called "anticholinergic drugs" can also affect these same chemicals, but in a different way. These drying medications might decrease the effects of barberry and might in turn decrease the effects of drying medications. Some of these drying medications include atropine, scopolamine, some medications used for allergies (antihistamines), and some medications used for depression (antidepressants).

Barberry might decrease blood sugar. Taking barberry along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed. Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, metformin (Glucophage), pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Barberry might decrease blood pressure in some people. Taking barberry along with medications used for lowering high blood pressure might cause your blood pressure to go too low. Do not take too much European barberry if you are taking medications for high blood pressure. Some medications for high blood pressure include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.

Barberry might slow blood clotting. Taking barberry along with medications that also slow clotting might increase the chances of bruising and bleeding. Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

Barberry might cause sleepiness and drowsiness. Medications that cause sleepiness are called sedatives. Taking barberry along with sedative medications might cause too much sleepiness. Taking barberry along with sedative medications used in surgery might cause prolonged sedation. Some sedative medications include pentobarbital (Nembutal), phenobarbital (Luminal), secobarbital (Seconal), thiopental (Pentothal), fentanyl (Duragesic, Sublimaze), morphine, propofol (Diprivan), and others.

Barberry might increase certain chemicals in the brain, heart, and elsewhere in the body. Some medications used for glaucoma, Alzheimer disease, and other conditions also affect these chemicals. Taking barberry with these medications might increase the chance of side effects.