Nuclear stress tests are used to diagnose heart problems by producing images of the heart at rest and after exercise. A technician injects a nuclear isotope into the patient and takes images with a nuclear camera of the resting heart, reports the University of Maryland Medical Center. For the second set of images, the patient either walks on a treadmill or receives intravenous medications to stress the heart to its maximum tolerance. The patient may be instructed to stop taking certain medications prior to the test to avoid false results and should follow all such directions exactly.
Caffeine
Caffeine may produce a false-negative result, so patients are instructed to avoid any products containing caffeine for 24 hours prior to the test, according to the Merck Manual. Some over-the-counter and prescription medications used for staying awake, relieving headaches or curbing appetite contain caffeine, notes the Cleveland Clinic. Patients must also avoid coffee, tea, chocolate and sodas containing caffeine, including those labeled as decaffeinated.
Asthma Medications
Certain asthma medications, including aminophylline and theophylline, can produce false-negative results, reports the Merck Manual. The patient should avoid these medications for 24 hours prior to the test, but should bring an inhaler with him to the testing site.
Diabetes Medications
The patient may not eat or drink anything for 4 to 6 hours prior to testing, so a diabetic patient should not take oral medication on the morning of the test, according to the Cleveland Clinic. The physician may recommend that an insulin-dependent diabetic take half of her usual dose and eat a light meal 4 hours before the test.
Heart Medications
Certain medications for heart conditions work by limiting the heart rate, an effect that would prevent the patient from reaching a maximal heart rate during a stress test. Unless instructed otherwise, nitrates--isosorbide dinitrate, isosorbide mononitrate or nitroglycerin--and beta blockers--atenolol, metoprolol and metropolol XL--should not be taken on the day before or the day of the test, according to Dr. Donald A. Underwood in a report published in the June 2002 issue of the "Cleveland Journal of Medicine."
Sexual Stimulants
Patients taking sexual stimulants should avoid them for 24 hours prior to the test, according to the University of Maryland Medical Center. A patient who has taken a sexual stimulant within 24 hours of the test could not be given nitroglycerin if he experiences chest pain.
