Intravenous Mannitol to reduce raised intra-ocular pressure (Guidelines)





  • North Highland, Western Isles and Orkney (ophthalmology service provided to these areas from Raigmore)


Acute angle-closure glaucoma (see resources) is a medical emergency requiring immediate treatment with therapies to lower intra-ocular pressure, which may include mannitol infusion. Any delays in treatment may be sight-threatening. Patients may present via the Eye Clinic or Emergency Department, and this protocol has been developed to provide guidance for nursing staff on all aspects of mannitol administration, as it is an uncommon occurrence and staff are unlikely to maintain familiarity/competency in this area.

Prescribing of mannitol infusion

Within normal working hours, patients presenting with acute angle-closure glaucoma will be managed under the care of an Ophthalmologist, who is responsible for the prescribing of mannitol.

Patients presenting out-of-hours (OOH) may be assessed and managed by OOH/Emergency Department doctors or Advanced Nurse Practitioners, following the management plan for Acute Angle-Closure Glaucoma within the Ophthalmology Emergency Protocols on TAM (see resources). This documents the role of mannitol infusion within the overall treatment pathway for acute angle-closure glaucoma. Ophthalmology will take over the care of the patient the next working day at 08.00.

Location of mannitol administration

  • Patients requiring intravenous mannitol should receive the infusion within an inpatient ward area. It is not appropriate for mannitol infusion to be administered in an outpatient setting.
  • Within the National Treatment Centre – Highland [NTC-H] it should be administered in the Inpatient Ward or Eye Day Case Unit, on a monitored bed or trolley.
  • When patients present via the Eye Clinic, clinic staff should liaise with clinical staff in the above areas to arrange administration. This should be treated as a clinical emergency to avoid delays in administration.


The following patients should not receive mannitol, please discuss with Ophthalmologist or prescriber if any concerns.
Treatment should not be delayed awaiting laboratory results, the patients should be assessed for cautions/contra-indications using the most recent pre-admission laboratory results.

  • Severe renal impairment, CKD 4 or 5 (eGFR <30ml/min/1.73m2) or haemodialysis/peritoneal dialysis
  • Severe hepatic impairment
  • Severe heart failure: New York Heart Association Stage 3 or 4 (significant limitation in activities or symptoms at rest) or hepatic impairment
  • Pulmonary oedema
  • Hypersensitivity to mannitol or any of its excipients (identified within Summary of Product Characteristics (SPC))
  • Pregnancy or breast feeding


The following groups of patients may require a reduce dose and/or more careful monitoring, please discuss with Ophthalmologist or prescriber:

  • Heart failure
  • Renal impairment (eGFR 30 to 50ml/min/1.73m2) – additional monitoring required, see also under “Monitoring and observations”
  • Frail elderly patients


Should the patient decline treatment, this must be discussed immediately with the Ophthalmologist or prescriber.

Qualifications and training of nursing staff administering therapy

  • Registered nurse
  • Completed the following:
    • Venepuncture training
    • Intravenous (IV) cannulation training
    • IV drug administration course
    • Sharps training module
  • Anaphylaxis training and Basic Life Support via Turas

Dose, prescribing and documentation

  • Standard dose: mannitol 10%, 500ml by intravenous infusion over 60 minutes
  • Prescribe on fluid prescription chart
  • It should also be recorded in the patient’s paper or electronic notes that mannitol was required and administered.

Monitoring and observations required

  • Routine bloods to be taken prior to infusion: FBC, U&E and bicarbonate. If patient is being treated at NTC-H, these can be sent on routine transport to Raigmore Laboratories; administration should not be delayed awaiting blood results.
  • Commence observations (routine NEWS2) 15 minutes prior to infusion, then every 15 minutes during infusion and at 30 minutes post infusion. A small rise in BP and HR may be observed during the infusion, but should not be sustained post infusion. A NEWS2 chart should be used for observations.
  • Monitoring patients with renal impairment or heart failure: fluid balance chart and monitoring of urine output should be performed whilst an inpatient especially if repeat doses required, and also bloods as above.
  • If patients have to have repeated infusions, then bloods should be repeated, depending on risk (e.g. frail or elderly, previous renal impairment), and at least before discharge. Ophthalmologist or prescriber to advise on blood tests required. Ophthalmologist should review blood results prior to discharge.

Method of administration and special precautions

  • Use administration set which includes a final in-line filter (15 micron filter) because of the potential for mannitol crystals to form. Standard Alaris and volumetric giving sets have a 15 micron filter. The equipment should be primed with the solution in order to prevent air entering the system.
  • Do not remove unit from overwrap until ready for use. The inner bag maintains the sterility of the product.
  • Use only if the solution is clear, without visible particles or discoloration and the seal is intact. Confirm the integrity of the bag. Use only if the container is undamaged. Administer immediately following insertion of the infusion set.
  • Mannitol is a hypertonic solution and should be administered via a large peripheral vein. Rapid infusion in peripheral veins may be harmful. Mannitol has a high osmolarity and may cause venous irritation and tissue damage. Monitor insertion site closely and re-site cannula if any signs of inflammation. See NHS Highland extravasation protocol on intranet.
  • Mannitol solutions may crystallize when exposed to low temperature. At higher concentrations, the solutions have a greater tendency to crystallize. Inspect for crystals prior to administration. If crystals are visible, re-dissolve by warming the solution up to 37°C followed by gentle agitation. Solutions should not be heated in water or in a microwave oven due to the potential for product contamination or damage. Only dry heat (for example: a warming cabinet) should be used. Allow the solution to cool to room or body temperature before re-inspection for crystals and use
  • Flush with glucose 5% (this is to avoid precipitation with sodium chloride 0.9%).

Advice to be provided to patients

  • Common side effects: cough, headache and vomiting. Uncommon side effects: dizziness, fever, malaise, nausea, pain and skin reactions
  • Ability to perform tasks that require mental or physical alertness or co-ordination may be impaired. Avoid driving
  • Ask patient to report any pain, stinging or redness at injection site
  • Offer a copy of the patient information leaflet to patient.

Identification and management of adverse effects

  • Monitor for symptoms of hypersensitivity, including airway, breathing or circulation problems, fever, flushing, urticaria, pruritus and angioedema. Monitor injection site (high pH; risk of extravasation)
  • If an adverse reaction does occur give immediate treatment and inform on call doctor based on site, and duty ophthalmologist as soon as possible.
  • Report the reaction to the MHRA using the Yellow Card System (see resources)

Referral to medical staff

  • All patients requiring IV mannitol should be discussed with the duty Ophthalmologist after administration for further advice and to recommend ongoing management (this may need to be within working hours, the next working day)
  • Appearance or suspicion of an adverse reaction, as above, should be discussed with medical staff.

Facilities and supplies required

  • Stock of 10% 500mls Mannitol
  • Glucose 5%
  • Access to BNF/SmPC/Injectable Medicines Guide

Last reviewed: 25/01/2023

Next review date: 31/01/2026

Author(s): Ophthalmology.

Version: 1

Approved By: TAM Subgroup of the ADTC

Reviewer name(s): Dr T Leslie, Consultant Ophthalmologist .

Document Id: TAM544

Internal URL:

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