How does topical benzocaine cause methemoglobinemia?

Acquired methemoglobinemia results from exposure to chemicals that oxidize the ferrous iron in hemoglobin to the ferric state at a rate that exceeds the reducing capacity of the methemoglobin reductase enzyme in erythrocytes. A wide variety of agents are known to induce methemoglobinemia (Table), including lidocaine.

Which local anesthetic can cause methemoglobinemia?

Drugs causing MetHb:

• local anesthetics: prilocaine (with lidocaine in EMLA cream.
• lidocaine.
• benzocaine (Hurricane spray, Cetacaine – benzo- and tetracaine)
• nitroglycerine, sodium nitroprusside.
• phenytoin.
• sulfonamides.
• metoclopramide.

What are the symptoms of methemoglobinemia?

What are the symptoms of methemoglobinemia?

• headache.
• shortness of breath.
• nausea.
• rapid heart rate.
• fatigue and lethargy.
• confusion or stupor.
• loss of consciousness.

How likely is it to get methemoglobinemia from Orajel?

The second most common dosage form was oral gel (n=20). Four cases resulted in death, including one infant and three adults. In 36 of the 119 cases (30 percent) the reported methemoglobin level was 30 to 55 percent, with the normal concentration typically around one to two percent.

Can you get methemoglobinemia from lidocaine use?

Methemoglobinemia, or exces – sive levels of methemoglobin (MetHb) in the blood,1 is a rare and unusual complication associated with lidocaine use, and many clinicians—particularly those who infre- quently use lidocaine or similar compounds—may be unaware of this potentially fatal condition.

What are the side effects of methemoglobinemia?

Methemoglobinemia is a rare blood disorder that can be life-threatening and result in severe side effects, including death. It can be caused by medications, including over-the-counter topical anesthetic Benzocaine.

Is there a risk for topical anesthetic induced methemoglobinemia?

Topical anesthetics are commonly used, and methemoglobinemia is a known and potentially life-threatening complication of these agents. However, little is known about the incidence of and risk factors for topical anesthetic–induced methemoglobinemia.

What happens if you take lidocaine and benzocaine?

Methemoglobinemia is a potentially severe complication of lidocaine and benzocaine, especially when used concomitantly. Among the acquired causes of methemoglobinemia, although caine-induced methemoglobinemia is rare, it may have a fatal outcome.