Conditions and symptoms
What Is Agranulocytosis? Why Labels Warn About Fever
Agranulocytosis · say it: ay-GRAN-yoo-loh-sy-TOH-sisAlso written: severe neutropenia, granulocytopenia
Short answer
Agranulocytosis is a serious drop in a type of white blood cell that fights infection, leaving the body much less able to fight germs.
What it means
Granulocytes, mainly neutrophils, are white blood cells that are the body's first defence against bacteria. In agranulocytosis their number falls to very low levels. The person may feel well until an infection starts, which can then become serious quickly. Fever, sore throat, mouth ulcers or flu-like illness while on a medicine that carries this warning need urgent medical attention and a blood test.
It is listed on labels because some medicines can rarely cause it, including clozapine, some antithyroid medicines, some antibiotics and metamizole (dipyrone). Labels explain which symptoms to report and whether regular blood counts are required, as with clozapine.
Neutropenia means a low neutrophil count of any degree; agranulocytosis is the most severe end. It is different from aplastic anemia, where all types of blood cell drop.
Where you may see it
- 'Warnings' sections of clozapine, antithyroid and some antibiotic labels
- Leaflets under 'Serious side effects: sore throat, fever'
- Full blood count reports showing very low neutrophils
📄 How it looks on a report
Agranulocytosis has been reported. Advise patients to report promptly any sore throat, fever or other signs of infection.
🙅 What it does not mean
- It is rare; being on the label does not mean it will happen to you.
- Not every sore throat means agranulocytosis, but on these medicines it should be checked.
- A slightly low white count is not the same as agranulocytosis.
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “Agranulocytosis”
Plain-English explanations of each medicine, from its official FDA label.
- Albendazole
an anthelmintic drug, a medicine used to treat infections caused by parasitic worms
- Carbamazepine
a mood stabilizer, and an anticonvulsant (seizure) medicine, according to the label
- Diphenhydramine Hydrochloride
an antihistamine (an antihistaminic agent) given by injection into a vein or deep into a muscle
- Furosemide
A loop diuretic, a type of medicine that helps the body get rid of extra fluid through urine
- Hydrochlorothiazide
A thiazide diuretic, a type of medicine often called a 'water pill'
- Mirtazapine
An antidepressant medicine. The label describes it as having a tetracyclic chemical structure and belonging to the piperazino-azepine group of compounds.
- Sulfamethoxazole and Trimethoprim
An antibacterial combination of two medicines: a sulfonamide antimicrobial and a dihydrofolate reductase inhibitor antibacterial.
🔗 Read more from trusted sources
- “Agranulocytosis” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “agranulocytosis”
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