If you are being treated with any of the following medications, you should not use psyllium supplements without first talking to your health care provider.

Antidepressant medications, Tricyclics -- Dietary fiber has been shown to lower the blood levels and effectiveness of tricyclic antidepressant medications in some patients. If you take tricyclic antidepressants, talk to your doctor before taking psyllium. Tricyclic antidepressants include:

• Amitriptyline (Elavil)
• Doxepin (Sinequan)
• Imipramine (Tofranil)

Carbemazepine (Tegretol) -- Taking psyllium with carbamazepine, a medication used to treat seizures, may decrease the absorption and effectiveness of carbamazepine.

Cholesterol-lowering medications (bile acid sequestrants) -- Taking psyllium with the cholesterol-lowering medications called bile acid sequestrants may help further lower cholesterol levels and may reduce side effects of colestipol. Talk to your doctor about whether this may be an option for you. Bile acid sequestrants include:

• Cholestyramine (Questram)
• Colestipol (Colestid)

Diabetes medications -- Fiber supplements may reduce levels of blood sugar, making the possibility of hypoglycemia (low blood sugar) more likely. Talk to your doctor before taking fiber supplements, as your dose of diabetes medications may need to be adjusted.

Digoxin -- Fiber supplements may reduce the absorption of digoxin, a medication used to regulate heart function. You should not take fiber supplements at the same time as digoxin.

Lithium -- Psyllium may lower lithium levels in the blood, reducing the effectiveness of this medication. If both are used, they should be taken at least 1 - 2 hours apart, and lithium levels should be monitored very closely by your doctor.