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Heparin sodium flush solution

Updated 2 Feb 2023 | Parenteral anticoagulants


Flushing solution containing heparin sodium

Drugs List

  • heparin sodium 200unit/2ml flush solution
  • heparin sodium 50unit/5ml flush solution
  • Therapeutic Indications


    Catheter/cannula patency - maintenance of



    10 to 200 units should be flushed through the catheter or cannula every 4 to 8 hours as required.


    (See Dosage; Adult)


    For injection into the indwelling catheter or cannula.


    History of heparin-induced thrombocytopenia

    Precautions and Warnings


    Do not administer systemically
    Monitor platelet count if used for more than 5 days
    Discontinue if thrombocytopenia occurs
    Repeated use of heparin flushes may cause systemic effects

    The role of heparin flushes in maintaining patency of arterial and central venous catheters is unclear. Systemic anticoagulant effects may be seen if a catheter or cannula is repeatedly flushed with heparin.

    Caution should be taken with patients sensitive to low molecular weight heparins.

    When an indwelling device is used for repeated withdrawal of blood for laboratory analyses, the presence of heparin or saline is likely to interfere with or alter results of the desired blood tests. In this case, before the desired blood sample is taken, the in situ heparin flush solution should be cleared from the device by aspirating and discarding a volume of solution equivalent to that of the indwelling venipuncture device.

    Pregnancy and Lactation


    Use heparin sodium flush with caution during pregnancy.

    The manufacturer states the dose of heparin in this product would not be expected to constitute a hazard. Heparin does not cross the placental barrier.

    Studies have failed to find detectable levels of heparin in the umbilical cord vein after it has been administered to pregnant women, or in the foetal circulation following dual perfusion of an isolated placental lobule (Schaefer, 2015). Heparins are one of the anticoagulants of choice during pregnancy.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Heparin is considered safe for use in breastfeeding.

    Heparin does not pass into breast milk, nor is it absorbed in relevant quantities in the infants gastrointestinal tract. Schaefer (2015) notes that breastfeeding can continue without limitations when the mother has been administered heparin.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Side Effects

    Anaphylactic shock
    Angioneurotic oedema
    Hypersensitivity reactions
    Sense of oppression


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: March 2017

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Summary of Product Characteristics: Heparin Sodium 100 I.U./ml flushing solution for maintenance of patency of intravenous devices. Wockhardt UK Ltd. Revised November 2015.

    Summary of Product Characteristics: Heparin Sodium 10 I.U/ml flushing solution for maintenance of patency of intravenous devices. Wockhardt UK Ltd. Revised December 2015.

    NICE Evidence Services Available at: Last accessed: 25 August 2017

    US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
    Available at:
    Heparin. Last revised: 06 November 2015
    Last accessed: 08 March 2017

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