Methemoglobinemia can happen as fast as a few minutes or methemoglobinemia can happen slowly over hours, depending on the agent and cause of the methemoglobinemia.
Some topical anesthetics cause issues and methemoglobinemia within 20 to 60 minutes, and others like nitrite exposure or dapsone can take overs for the symptoms of methemoglobinemia to appear, even up to 10 hours or longer for transformation.
The first signs of methemoglobinemia are bluish skin also known as cyanosis, especially around the lips and nails, and the bluish skin with methemoglobinemia is often also accompanied with other symptoms like shortness of breath, fatigue, dizziness and headache.
The key indicator of methemoglobinemia is also hypoxia, which is low blood oxygen, that does not improve with oxygen.
Sometimes a person with methemoglobinemia may also have noticeably chocolate brown colored blood.
The symptoms of methemoglobinemia will also depend on the severity of the , but methemoglobinemia often starts with mild signs like paleness (10-20% MetHb)and progress to confusion, rapid heart rate and weakness (20-45% MetHb as levels rise.
The early signs of methemoglobinemia, which occur at MetHb of 10-20% are bluish tint to skin, lips and nail beds and is sometimes described as slate gray.
Pale skin or pallor and sometimes no symptoms in early methemoglobinemia in healthy people, but people with underlying issues may feel weakness or fatigue.
Moderate signs of methemoglobinemia at MetHb 2-45% are shortness of breath or dyspnea, headache and dizziness, fatigue and weakness, increased heart rate also known as tachycardia and Rapid breathing also known as tachypnea and nausea and vomiting.
The key diagnostic clues of methemoglobinemia are refractory cyanosis, with bluish skin color that does not go away with supplemental oxygen, chocolate brown colored blood.
And a pulse oximeter that shows low oxygen or SpO2 Gap, but arterial blood gas is (SaO2) is also low and inconsistent.
You should seek emergency care if you have symptoms like seizures, confusion, severe drowsiness, loss of consciousness or extreme difficulty breathing, as severe cases of methemoglobinemia with MetH>50% can be life threatening.
Methemoglobinemia is a blood disorder where too much methemoglobin forms, reducing the blood's ability to carry oxygen to the body, leading to symptoms like bluish skin (cyanosis), headache, dizziness, and shortness of breath, often triggered by certain drugs (like benzocaine, dapsone) or toxins (nitrates in water) and sometimes inherited, with treatment typically involving methylene blue and oxygen.