mannitol at a glance
Medicine class
Osmotic diuretic when infused; bronchial provocation agent when inhaled.
Administration
Given into a vein by clinical staff or inhaled during a supervised lung-function test.
What is mannitol used for?
Selected products are licensed for:
Identifying bronchial hyperresponsiveness using supervised inhalation and repeated spirometry.
Promoting urine production during the potentially reversible oliguric phase of acute renal failure.
Reducing intracranial pressure and cerebral oedema when the blood–brain barrier is intact.
Reducing raised intraocular pressure when other measures cannot lower it.
Increasing elimination of certain substances excreted through the kidneys in poisoning.
How does mannitol work?
Intravenous mannitol draws water into the bloodstream and retains water in the urine, increasing urine flow. It can also move water out of brain or eye tissue. Inhaled mannitol increases airway-fluid osmolarity, which can narrow sensitive airways and be detected by spirometry.
mannitol preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 10%, 15% w/v
Capsule
Route: Oral
Strengths: 40 mg
How to take mannitol
Mannitol is administered by trained healthcare professionals.
Infusion is given into a vein; staff inspect the solution and use a final in-line filter.
Osmohale capsules are inhaled through the supplied device during a supervised test and must not be swallowed.
Follow the testing department’s instructions about temporarily withholding medicines and avoiding caffeine before a challenge test.
mannitol side effects
Common or expected effects
- During inhalation testing: cough, breathlessness, chest tightness or worsening asthma symptoms
- Throat pain or irritation, runny nose, headache, nausea or vomiting
- With infusion: thirst, dry mouth, headache, dizziness, nausea or infusion-site irritation may occur, but frequency is unknown
Get urgent medical advice
- Severe bronchospasm or falling oxygen levels
- Severe allergic reaction
- Fluid overload or pulmonary oedema causing worsening breathlessness
- Serious dehydration or electrolyte disturbance, which may cause confusion, abnormal heart rhythm or seizures
- New or worsening kidney failure, falling urine output or blood in the urine
- Tissue injury from leakage around the infusion site
mannitol in pregnancy
Osmohale should not be given during pregnancy because the effect of an induced airway reaction is unknown. Evidence for intravenous mannitol is limited, so it should be used only when clearly needed.
mannitol while breastfeeding
Osmohale may be used while breastfeeding because systemic exposure after inhalation is negligible. It is unknown whether intravenous mannitol enters breast milk, so infusion should be used only when clearly needed after clinical assessment.
mannitol interactions
The clinical team should review all medicines before mannitol is used.
Asthma and allergy medicines
Bronchodilators, inhaled corticosteroids, antimuscarinics, theophylline, antihistamines and leukotriene antagonists can reduce airway responsiveness and alter an Osmohale result.
Other diuretics
They may increase diuretic effects and the risk of fluid or electrolyte disturbance.
Lithium
Mannitol increases lithium excretion and may reduce its therapeutic effect.
Aminoglycosides or ciclosporin
Renal and neurological toxicity may be increased, requiring close monitoring.
Common questions about mannitol
Answers are fully visible for fast scanning and source review.
Is mannitol a diuretic?
Intravenous mannitol is an osmotic diuretic. It retains water in the kidney filtrate, increasing urine flow and electrolyte excretion.
Can mannitol be used to test for asthma?
Inhaled mannitol tests whether the airways are unusually sensitive. Results are interpreted alongside symptoms and other clinical findings.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.