Rarely, this product causes potentially severe reactions, mostly if taken at high doses or with some other drugs. If you experience agitation, confusion, diarrhea, fever, tremor and muscular rigidity or contractions, you should contact your doctor. Because this medication may affect your ability to perform tasks requiring alertness, such as driving a car, it is advised to wait until you are familiar with the effects of your medication before engaging in these activities. This medication may interact with other medications or supplements, sometimes significantly. Many interactions, however, may be dealt with by a dosage adjustment or a change in medication schedule. Check with your pharmacist before using this medication in combination with any other medications (including non-prescription products), vitamins or natural products.