To: Editors & Health Journalists

Issued by: Department of Health

Date: Monday, 18 January 2021


Blood thinners for COVID-19 patients


Pretoria: Patients with severe COVID-19 symptoms may develop extensive blood clotting, which can cause serious health problems and death. For this reason, many guidelines, including the South African guidelines have recommended the use of blood thinners (usually low-molecular weight heparin) for all hospitalised patients with COVID-19.


The blood thinner can be given in two different doses: low-dose to reduce the risk of blood clots developing and high-dose to treat blood clots that have already developed. The risk of bleeding is a lot higher with high-dose blood thinners. High-dose blood thinners have been recommended for the most severely ill COVID-19 patients, even if there is no proof that blood clots have formed, because it is difficult to exclude small blood clots.

Recently, evidence2 has emerged from a large randomised controlled clinical trial (a collaboration of three international groups) that high-dose compared to low-dose blood thinners did not help critically ill ICU patients. This new evidence also suggests that high-dose blood thinners may harm critically ill patients. Because of these findings, the trial oversight committees have recommended stopping further enrolment of critically ill patients to the trial.

No data is available yet to review these findings. However, the clinical trial design is strong and the National Essential Medicines List sub-committee on COVID-19 recommends against the use of high-dose blood thinners in critically ill patients with COVID-19.

In the absence of contraindications, low-dose blood thinners are still recommended for all hospitalised patients, as recommended in the rapid review3 and Standard Treatment Guidelines and Essential Medicines List.



For more information, please contact:


Mr Popo Maja

National Health Department Spokesperson

Cell: 0725853219