Methemoglobinemia: Overview of Causes and Treatment
Explore methemoglobinemia, its causes, symptoms, and treatment options. Understand how this blood disorder affects oxygen delivery and ways to manage it effectively.
Written by Dr. Siri Nallapu
Reviewed by Dr. D Bhanu Prakash MBBS, AFIH, Advanced certificate in critical care medicine, Fellowship in critical care medicine
Last updated on 27th Aug, 2025
Methemoglobinemia is a rare but serious blood disorder where an abnormal form of hemoglobin (called methemoglobin) builds up in the blood, reducing its ability to carry oxygen efficiently. This condition can lead to symptoms like shortness of breath, fatigue, and even life-threatening complications if left untreated.
In this article, we’ll discuss what methemoglobinemia is, its causes, symptoms, and available treatments in a simple and easy-to-understand way.
What is Methemoglobinemia?
Hemoglobin is a protein in red blood cells that carries oxygen from the lungs to the rest of the body. Normally, hemoglobin binds oxygen and releases it where needed. However, in methemoglobinemia, some hemoglobin gets converted into methemoglobin, a form that cannot release oxygen properly.
When too much methemoglobin accumulates, the blood cannot deliver enough oxygen to tissues and organs, leading to a condition called hypoxia (low oxygen levels).
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Types of Methemoglobinemia
There are two main types:
1. Congenital (Inherited) Methemoglobinemia – A rare genetic condition where the body produces too much methemoglobin due to enzyme deficiencies.
2. Acquired Methemoglobinemia – More common and caused by exposure to certain medications, chemicals, or toxins.
Common Causes of Methemoglobinemia
Below are few common causes of Methemoglobinemia,
1. Inherited Causes
Some people are born with a genetic mutation that affects the enzyme cytochrome b5 reductase, which normally converts methemoglobin back to hemoglobin. Without this enzyme, methemoglobin builds up.
2. Acquired Causes (More Common)
This type occurs due to exposure to certain substances, including:
Medications:
- Local anesthetics (benzocaine, lidocaine)
- Antibiotics (dapsone, nitrofurantoin)
- Antimalarial drugs (chloroquine, primaquine)
Chemicals & Toxins:
- Nitrates (found in contaminated water, fertilizers)
- Nitrites (used in food preservatives)
- Industrial chemicals (aniline dyes, benzene derivatives)
Babies are particularly vulnerable because their bodies are less efficient at converting methemoglobin back to normal hemoglobin.
Symptoms of Methemoglobinemia
Symptoms depend on the level of methemoglobin in the blood:
Mild Cases (10-20% methemoglobin):
- Bluish or grayish skin (cyanosis)
- Fatigue
- Headache
- Shortness of breath
Moderate to Severe Cases (20-50% or higher):
- Confusion
- Rapid heartbeat
- Dizziness or fainting
- Chest pain
- Seizures or coma (in extreme cases)
If methemoglobin levels exceed 50-60%, the condition can be life-threatening and requires emergency treatment.
Diagnosis of Methemoglobinemia
If a doctor suspects methemoglobinemia, they may perform:
- Pulse oximetry (though it may give misleading readings in this condition).
- Arterial blood gas test (to check oxygen levels).
- Methemoglobin blood test (confirms the diagnosis).
- Genetic testing (if inherited causes are suspected).
Treatment Options
Below are few treatment options of Methemoglobinemia,
1. Methylene Blue Therapy
- The most common treatment for severe cases.
- Given intravenously (IV) to convert methemoglobin back to normal hemoglobin.
Note: People with G6PD deficiency (a genetic condition) should not take methylene blue as it can cause complications.
2. Oxygen Therapy
- Supplemental oxygen helps improve oxygen delivery to tissues.
3. Blood Transfusion (In Extreme Cases)
- If methylene blue is ineffective, a blood transfusion may be needed.
4. Avoiding Triggers
- If caused by medications or chemicals, stopping exposure is crucial.
5. Genetic Counseling (For Inherited Cases)
- Families with inherited methemoglobinemia may benefit from genetic counseling.
Prevention & Lifestyle Tips
- Avoid known triggers (certain medications, contaminated water, industrial chemicals).
- Check well water for nitrates if living in rural areas.
- Inform doctors about any family history of blood disorders before taking new medications.
- Stay hydrated to help flush out toxins.
When to See a Doctor?
Seek immediate medical help if you or a loved one experience:
- Severe shortness of breath
- Bluish lips or skin
- Confusion or loss of consciousness
If you have concerns or need expert advice, you can book a consultation with a hematologist on Apollo 24|7 for personalized care.
Early treatment can prevent serious complications.
Final Thoughts
Methemoglobinemia is a rare but treatable condition. While inherited forms are uncommon, acquired cases can be prevented by avoiding certain medications and chemicals. If you suspect symptoms, consult a doctor immediately for proper diagnosis and treatment.
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Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
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HealthYou Speciality Clinic & Diagnostics., Kolkata
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108 DHANA DHANVANTARI Clinic, Kolkata
(25+ Patients)
Dr. Gunashree V L
General Physician/ Internal Medicine Specialist
3 Years • MBBS
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Apollo Clinic, JP nagar, Bengaluru
Dr. Dhanraj K
General Physician/ Internal Medicine Specialist
25 Years • MBBS, MD Internal Medicine - Osmania Medical College, Hyderabad
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(375+ Patients)
Dr. Anand Ravi
General Physician
2 Years • MBBS
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PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Consult a Top Specialist
Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
Kolkata
HealthYou Speciality Clinic & Diagnostics., Kolkata
Dr. Harshendra Jaiswal
General Physician/ Internal Medicine Specialist
12 Years • MBBS , MD (General medicine)
Kolkata
108 DHANA DHANVANTARI Clinic, Kolkata
(25+ Patients)
Dr. Gunashree V L
General Physician/ Internal Medicine Specialist
3 Years • MBBS
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
Dr. Dhanraj K
General Physician/ Internal Medicine Specialist
25 Years • MBBS, MD Internal Medicine - Osmania Medical College, Hyderabad
Hyderabad
Apollo Hospitals Jubilee Hills, Hyderabad
(375+ Patients)
Dr. Anand Ravi
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
