People on Certain Beta Blockers Should Be Wary of Epinephrine

Beta blockers are widely prescribed to lower blood pressure and for other purposes. In 2007, more than 86 million prescriptions were filled for these drugs.

But since the 1970s, case studies have shown that the interaction of certain beta blockers and epinephrine (adrenalin) can raise blood pressure. One report, for instance, described a 22-year-old man on propranolol (INDERAL) who was given epinephrine to treat an allergic reaction to a blood transfusion. He soon developed a blood pressure of 220/130 with a severe headache and weakness of his right arm and leg.

What causes the spike in blood pressure?

Epinephrine simultaneously constricts (shrinks) and dilates (opens) the arterioles (smaller arteries that branch out to form capillaries). The result is that the average blood pressure does not change drastically when the amount of epinephrine circulating in the blood is elevated.

However, taking a drug that blocks the dilating effects of epinephrine, such as a non-selective beta blocker, leaves the constricting effects unopposed. This results in an increase in blood pressure.

Does this interaction occur with all beta blockers?

No. Although all “non-selective” beta blockers, such as carvedilol (COREG) and propranolol, are likely to produce the same hypertensive effect if epinephrine is given, “cardioselective” beta blockers, such as metoprolol (LOPRESSOR), do not appear to produce hypertensive reactions when epinephrine is given (see Table). This is because the cardioselective beta blockers have much less effect in blocking the blood vessel dilating effects of epinephrine and therefore do not result in a net increase in blood pressure.

Who is at risk for this interaction?

Virtually anyone who receives the combination of a non-selective beta blocker and epinephrine may experience a dramatic increase in blood pressure.

Although most people would just have a bad headache from the interaction, occasionally, a severe reaction like a stroke may occur.

Because it is usually not possible to know ahead of time if a person has a pre-existing abnormality in the blood vessels in the brain (which might increase the chances of a stroke), the best course is to avoid the use of a non-selective beta blocker and epinephrine together.

People taking a beta blocker who have allergies severe enough to require them to carry an epinephrine injection (such as EPI-PEN) may not experience the beneficial effects of epinephrine should they develop anaphylaxis. Talk to your prescriber about this issue; he or she may want you to use a blood pressure-lowering drug other than a beta blocker.

More to watch for: Epinephrine and local anesthetics

The reported cases of hypertensive crises (sudden sharp elevations of blood pressure) involved full systemic doses of epinephrine, but sometimes people get smaller amounts.

In some cosmetic surgical procedures, enough epinephrine may be used to interact with a beta blocker, even though it is injected locally.

When six patients on propranolol undergoing facial or eyelid surgery were injected with lidocaine and epinephrine, they developed elevated blood pressures. However, much smaller amounts of epinephrine such as is used in dental work and minor dermatologic procedures, appear less likely to be a problem in people receiving nonselective beta blockers.

Nevertheless, you should always let the health care professional know you are on a beta blocker before undergoing any procedure that involves doses of epinephrine and local anesthetics.

What You Can Do

Patients taking a non-selective beta blocker should make sure the provider is aware of this before they receive an injection of epinephrine, as your physician or other health care provider may not be aware that a systemic dose of epinephrine may produce a dangerous spike in blood pressure.

Table. Non-selective and cardioselective beta blockers