Does Trandate (labetalol) cause side effects?

Trandate (labetalol) is a beta-blocker used to treat high blood pressure (hypertension). 

Nerves from the adrenergic nervous system travel from the spinal cord to the arteries where they release norepinephrine. Norepinephrine attaches to adrenergic receptors on arteries and causes the arteries to contract, narrowing the arteries, and increasing blood pressure

Trandate blocks receptors of the adrenergic nervous system. When Trandate attaches to and blocks the receptors, arteries expand, resulting in a fall in blood pressure. 

The brand name Trandate is discontinued; generic forms of labetalol are available. 

Common side effects of Trandate include

Serious side effects of Trandate include

  • sexual dysfunction,
  • abnormal heart rhythm,
  • slow heart rate,
  • liver failure, and
  • allergic reactions.

Drug interactions of Trandate include medications that lower blood sugar such as insulin or oral antidiabetic medications, because Trandate can mask early warning symptoms of hypoglycemia (low blood sugar) such as tremors and increased heart rate, which are the result of activation of the adrenergic nervous system. 

Combining Trandate with tricyclic antidepressants such as amitriptyline, imipramine, or nortriptyline may lead to an increase in tremor which is a side effect of tricyclic antidepressants

If combined with adrenergic stimulating drugs used for treating asthma, for example, albuterol or pirbuterol, the adrenergic blocking effects of Trandate may counteract the effects of the stimulating drugs and reduce their effectiveness for treating asthmatic attacks. More of the adrenergic drug may be needed. 

Glutethimide may decrease the effectiveness of Trandate by increasing its elimination. When both drugs are used together, more Trandate or less glutethimide may be needed. 

Cimetidine may increase the effectiveness of Trandate by blocking its elimination and increasing its levels in the blood. Therefore, less Trandate may be needed when cimetidine and Trandate are used together. 

Halothane anesthesia may contribute to the blood pressure lowering effects of Trandate. 

There are no adequate studies of Trandate during pregnancy. Trandate is excreted in breast milk. It should be used cautiously in breastfeeding mothers because of the risk that the infant may develop a slow heart rate.

What are the important side effects of Trandate (labetalol)?

The most common side effects of labetalol are:

Postural hypotension (a rapid decrease in blood pressure when going from the lying or seated position to the standing position that may cause light-headedness or fainting) occurs rarely. Patients should be observed for this possible side effect within two to four hours of the first labetalol dose and after any changes in dose.

Other important side effects include:

  • sexual dysfunction,
  • abnormal heart rhythm,
  • slow heart rate,
  • liver failure, and
  • allergic reactions.

Trandate (labetalol) side effects list for healthcare professionals

Most adverse effects are mild and transient and occur early in the course of treatment. In controlled clinical trials of 3 to 4 months' duration, discontinuation of Trandate (labetalol) Tablets due to one or more adverse effects was required in 7% of all patients.


The incidence rates of adverse reactions listed in the following table were derived from multicenter, controlled clinical trials comparing labetalol HCl, placebo, metoprolol, and propranolol over treatment periods of 3 and 4 months. Where the frequency of adverse effects for labetalol HCl and placebo is similar, causal relationship is uncertain.

The rates are based on adverse reactions considered probably drug-related by the investigator. If all reports are considered, the rates are somewhat higher (e.g., dizziness, 20%; nausea, 14%; fatigue, 11%), but the overall conclusions are unchanged.

Labetalol HCI
(n = 227)
(n = 98)
(n = 84)
(n = 49)
Body as a whole
  Abdominal pain0012
  Taste distortion1000
Central and peripheral nervous systems
Autonomic nervous system
  Nasal stuffiness3000
  Ejaculation failure2000
  Increased sweating<1000
  Postural hypotension1000
Special senses
  Vision abnormality1000


Clinical trials also included studies utilizing daily doses up to 2,400 mg in more severely hypertensive patients. Certain of the side effects increased with increasing dose, as shown in the following table that depicts the entire US therapeutic trials data base for adverse reactions that are clearly or possibly dose related.

Labetalol HCl Daily Dose (mg)2003004006008009001,2001,6002,400
Number of patients522181606608503117411242175
Dizziness (%)23335191316
Nausea< 10124071119
Vomiting00< 1< 1< 10123
Nasal stuffiness112222456
Ejaculation failure021230435


Body as a Whole: Fever.


Central and Peripheral Nervous Systems: Paresthesia, most frequently described as scalp tingling. In most cases, it was mild and transient and usually occurred at the beginning of treatment.

Collagen Disorders: Systemic lupus erythematosus, positive antinuclear factor.

Eyes: Dry eyes.

Immunological System: Antimitochondrial antibodies.


Musculoskeletal System: Muscle cramps, toxic myopathy.

Respiratory System: Bronchospasm.

Skin and Appendages: Rashes of various types, such as generalized maculopapular, lichenoid, urticarial, bullous lichen planus, psoriaform, and facial erythema; Peyronie's disease; reversible alopecia.




Potential Adverse Effects


Central Nervous System



Intensification of A-V block (see CONTRAINDICATIONS).




Agranulocytosis, thrombocytopenic or nonthrombocytopenic purpura.


Mesenteric artery thrombosis, ischemic colitis.


Clinical Laboratory Tests

There have been reversible increases of serum transaminases in 4% of patients treated with labetalol HCl and tested and, more rarely, reversible increases in blood urea.

What drugs interact with Trandate (labetalol)?

  • In one survey, 2.3% of patients taking labetalol HCl in combination with tricyclic antidepressants experienced tremor, as compared to 0.7% reported to occur with labetalol HCl alone. The contribution of each of the treatments to this adverse reaction is unknown, but the possibility of a drug interaction cannot be excluded.
  • Cimetidine has been shown to increase the bioavailability of labetalol HCl. Since this could be explained either by enhanced absorption or by an alteration of hepatic metabolism of labetalol HCl, special care should be used in establishing the dose required for blood pressure control in such patients.
Risk of Anaphylactic Reaction

Drug/Laboratory Test Interactions

  • The presence of labetalol metabolites in the urine may result in falsely elevated levels of urinary catecholamines, metanephrine, normetanephrine, and vanillylmandelic acid when measured by fluorimetric or photometric methods. In screening patients suspected of having a pheochromocytoma and being treated with labetalol HCl, a specific method, such as a high-performance liquid chromatographic assay with solid-phase extraction (e.g., J Chromatogr 385:241,1987) should be employed in determining levels of catecholamines.
  • Labetalol HCl has also been reported to produce a false-positive test for amphetamine when screening urine for the presence of drugs using the commercially available assay methods TOXI-LAB A (thin-layer chromatographic assay) and EMIT-d.a.u. (radioenzymatic assay).


Trandate (labetalol) is a beta-blocker used to treat high blood pressure (hypertension). Common side effects of Trandate include fatigue, dizziness, nausea, headache, diarrhea, fluid retention (edema), shortness of breath, and rarely, postural hypotension (a rapid decrease in blood pressure when going from the lying or seated position to the standing position that may cause light-headedness or fainting). There are no adequate studies of Trandate during pregnancy. Trandate is excreted in breast milk. It should be used cautiously in breastfeeding mothers because of the risk that the infant may develop a slow heart rate.

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Medically Reviewed on 10/1/2020
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