Hypertension Home > Important Info on Propranolol/HCTZ

What If I Overdose on This Medicine?

As with most medications, it is possible to take too much propranolol/HCTZ. Symptoms of an overdose may include but are not limited to:
  • Extremely low blood pressure (hypotension)
  • A very slow heart rate (bradycardia)
  • Breathing problems
  • Low energy and weakness
  • Low levels of blood electrolytes, such as sodium, potassium, and chloride.
If you happen to overdose on this medication, seek immediate medical attention.
(Click Inderide Overdose for more information.)

What Should I Do If I Forget a Dose?

If you forget to take your propranolol/HCTZ dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the one you missed and continue with your regular schedule. Do not take a double dose.

How Does Propranolol/HCTZ Work?

Because propranolol/HCTZ combines two blood pressure drugs, it works in two different ways to lower blood pressure.
Propranolol, one of the components in the medication, is a beta-adrenergic blocking agent, or beta blocker for short. Beta blockers work by blocking beta receptors. These receptors are located in a number of places within the body, including the heart and blood vessels. Normally, when stress hormones (such as adrenaline) bind to beta blockers, certain reactions occur in the body, such as an increase in:
  • Heart rate
  • Blood pressure
  • The force with which the heart pumps blood.
By blocking beta receptors, propranolol causes the reverse effect of stress hormones. It decreases heart rate, blood pressure, and the workload on the heart, so the heart requires less oxygen and blood to work properly.
Propranolol also blocks beta receptors in the lungs. This can cause the air passages in the lungs (the bronchi) to narrow, leading to breathing problems, especially in people with emphysema, asthma, or other breathing difficulties. This is why propranolol may not be a good choice for people with breathing problems.
Hydrochlorothiazide (HCTZ), the other component of the medicine, is a diuretic or "water pill." It works by increasing the amount of salt and water the kidneys remove from the blood. This extra salt and water is then passed out through the urine. This action decreases blood volume, resulting in lower blood pressure.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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