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Side Effects of Labetalol (Normodyne, Trandate)


Side Effects of Labetalol (Trandate)

Labetalol, which is available under the brands Trandate and Normodyne, belong to the group of medicines called beta blockers. It works by blocking both alpha and beta receptors in the body. It is used to treat alone or in combination with other medicines, such as diuretics to lower blood pressure.

Precautions before Taking Trandate

You should not use Trandate if you are allergic to it, have second- or third-degree (complete) heart block, or moderate to severe first-degree heart block after a heart attack, heart failure. Do not take Trandate if you have abnormal electrocardiogram (ECG) (prolonged QT interval), shock caused by serious heart problems, have asthma, obstructive airway disease, other breathing disorders, or have severe slow heartbeat or severe low blood pressure.


Elderly people may be more sensitive to its effects, especially dizziness, lightheadedness, or fainting so Trandate should be used with caution.


If you become pregnant, contact your doctor. You will need to be informed of the benefits and risks of using Trandate during your pregnancy. Trandate is excreted in human breast milk and should be used cautiously in nursing mothers because of the risk that the infant may develop a slow heart rate.

Common Side Effects

According to the Trandate label reported by the FDA, the most common side effects associated with Trandate are:


  • Dizziness
  • Lightheadedness
  • Nausea
  • Temporary tingling sensation of the scalp
  • Tiredness
  • Stuffy nose
  • Increased levels of urea and creatinine in your blood (which could mean kidney failure)
  • Posture related decrease in blood pressure
  • Absence of ejaculation
  • Abnormal sensations

Drug Interactions

Some side effects such as drowsiness, dizziness, or lightheadedness, may worsen if you consume alcohol, are in hot weather, exercise, have a fever, or take certain medicines combined with Trandate. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects. Avoid driving or performing other possibly unsafe tasks until you are sure about these effects on you.


Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel “normal.” Inform your healthcare provider if you develop any new symptoms.


Tell your health care provider if you are taking any other medicines, especially any of the following: calcium channel blockers (verapamil), cimetidine (Tagamet), or digoxin because they may increase the risk of Trandate’s side effects The side effects of general anesthetics (halothane), nitroglycerin, or tricyclic antidepressants (amitriptylines such as Endep) may be increased by Trandate. Trandate may decrease the effectiveness of beta agonists, such as albuterol.


Trandate can mask early warning symptoms of hypoglycemia (low blood sugar) such as tremors and increased heart rate. People with diabetes taking medications that lower blood sugar, such as insulin or oral anti diabetic medications may need to increase the frequency with which they monitor their blood sugar in order to prevent hypoglycemia.

About Pharmacogenetic Testing

Trandate is metabolized in the body by the polymorphisms CYP2D6 and CYP2C19. Enzymes and genetic variations in CYP2D6 and CYP2C19 may be the reasons for difference in its effects, whether they are beneficial or adverse effects. Pharmacogenetic testing determines activity of these enzymes in an individual and may aid healthcare providers to tailor Trandate treatment.

Know Your Risk with the Rxight® Genetic Test

The Rxight® genetic test examines genes that show how well the body takes in medications. This guides prescribers in finding the optimal dosages or alternative medicines to prevent harmful side effects form occurring. With a simple cheek swab test, Rxight® provides you and your health care provider genetic information on how your genes respond to medicines.


Call us to learn more about Rxight® at 1-888-888-1932 or email us at support@Rxight.com.


Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

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