CME INDIA Presentation by Admin.

  • Dr Prabhat Agarwal, Agra and Dr Monica Arora, Varanasi ask – Serum institute and Bharat Biotech mention in their list to avoid vaccination if the patient is on blood thinners. So, what is the carry home message for blood thinners and covid vaccination. Site bleeding possible?
  • What to do if patient is on warfarin?
  • What to do if patient on Clopidogrel? Aspirin?

Covid-19 and Blood Thinners

Covaxin – Fact Sheet to Avoid Vaccination
If History of Allergy
If have got Fever
If have a bleeding disorder or are on a Blood Thinner
If Immunocompromised or on a medicine that affects your immune system
In Pregnancy
If Breast-feeding
If received another COVID Vaccine

COVISHIELD makers also mention that the recipients should mention to the healthcare provider, if they have fever, if they have a bleeding disorder or are on a blood thinner and also if they are immuno-compromised or are on a medicine that affects immune system.

What comes in Blood Thinners?

As per literature two categories of blood thinners: antiplatelets and anticoagulants are available.


Oral in our practice: Aspirin, Clopidogrel Ticagrelor, Prasugrel. The injectable or intravenous antiplatelet drugs include: Tirofiban, Eptifibatide.


There are three classes of anticoagulants:

  • Heparin and low molecular weight heparin
  • Vitamin K antagonists, such as warfarin
  • Newer direct oral anticoagulants

Vitamin K antagonistsNewer direct oral anticoagulantsHeparins
Warfarin (Coumadin)Dabigatran (Pradaxa)Heparin
Edoxaban (Savaysa)Enoxaparin (Lovenox)
Rivaroxaban (Xarelto)Dalteparin (Fragmin)
Apixaban (Eliquis)

CME INDIA Discussion:

Dr Ambrish Mithal DM Endo, Delhi:

  • This blood thinner thing – is there any basis for this? Half my patients will get excluded. We should check if they are following this in UK with the same vaccine. If it’s not a contraindication to Oxford vaccine in the UK, why should it be a contraindication to Covishield in India.
  • Public Health England and the Department of Health have said that you can have the vaccine if your anticoagulant treatment is stable. Injections into your muscle may bleed a little more than injections that are given under the skin, but less than those that are given into a vein.
  • If you are taking a blood thinner such as warfarin, or a new anticoagulant, the bleeding may take a little longer to stop and you may get more bruising on your upper arm.
  • We should rebut this strongly. So many people calling.
  • British Heart Foundation, a charity for heart and circulatory diseases, said the Covid jab poses less of bleeding risk than other types of jab. Like most vaccines, the coronavirus vaccine is injected into the muscle of your upper arm. As with any injection, there is some risk of bleeding.

Dr Manoj Chawla. Diabetologist, Mumbai:

  • A lot of doctors who have already taken the vaccine including covaxin have been on these blood thinners and had no issues.
  • Theoretically, the risk is the same for any IM injection for someone on aspirin and clopidogrel which is minimal.  Unnecessary confusion and scare.

Dr Purvi Chawla, Diabetologist, Mumbai:

  • But this has not been clarified enough. Patients are asking their doctors to clarify as this is doing the WhatsApp rounds. They shouldn’t have caused this stir and half message here.
  • There should be an official guideline to those in charge of vaccine administration. None of us were even asked if we had any of the contraindicated conditions or medications ongoing, before the vaccine was administered.

Dr Deepak Gupta, DM Card Pulse Hospital, Ranchi:

  • No issue with clopidogrel and Aspirin.
  • Patient on Oral anticoagulant may get local hematoma.

Dr Vijay Laxmi, Interventional cardiologist & Paediatric Echo cardiologist, Bangalore:

  • Better not advise to stop Aspirin or clopidogrel before vaccination for the fear of hematoma or ecchymosis instead press the site of injection for few minutes.
  • Risk is much less with vaccine as the amount is just half ml and needle are very fine and short.
  • I have seen many nurses injecting vaccine are not withdrawing to check if blood comes, they should be instructed.


Dr Awadhesh K Singh, DM Endo., Kolkata: 

  • Exactly! This is not exclusive for any vaccine but for all IM injection those who are on anticoagulants.
  • Apparently Medical fraternity making more noises than lay people in this case – the reason people are more scared.

Covid-19 and Blood Thinners
Joy of taking Vaccine: Dr Sanjeev Yadav, Asso.Prof. of Haematology, SGPGI, Lucknow, Says: All patients on blood thinner should take vaccination, unless they are on any immunosuppressive drugs as well, taking blood thinner is not at all a contraindication for COVID19 vaccination. These blood thinners may be anticoagulant or anti-platelet

Dr Mangesh Tiwaskar, API Sec, National:

  • True. I am on with Aspirin since I had Covid in July 2020, yesterday I got vaccinated… No haematoma till now at Injection site… No other side effect.

Covid-19 and Blood Thinners

Dr Mahadev Desai, Senior Physician, Ahmedabad:

  • Probably because in clinical trials, the persons on these drugs were not included, the Drug Authorities would want the manufacturers to mention such narratives in the product insert of such vaccines.
  • In case of Covaxin, since its approval is in “clinical mode,” it is imperative to exclude patients on blood-thinners. “So, it becomes an “off label” but justifiable use with usual precautions in individuals such as those at high risk of covid19 infection.
  • So many of our colleagues currently on anti-platelets (including DAPT) in Ahmedabad have received Covishield vaccine without any excess local or systemic adverse effects other than the ones observed in general population.

Dr Venkatesh Molio, Maregoan Goa:

  • No need to withhold vaccination if on Anti-Platelets.

Dr Keyur Acharya, Intensivist, UK:

  • Please refer to Green book which should be available freely. It’s standard book for all vaccination used extensively to check usual vaccinations and travel related vaccinations in adults.
  • Israel has vaccinated 10% of its population and US around 2% and UK approximately 7% so far. This issue has not been raised anywhere else.

CME INDIA Learning Points

  • A COVID-19 vaccination has brought a glimmer of light in an exceptionally challenging and painful year of the COVID-19 pandemic.

  • The use of intramuscular injections is widely recommended to be avoided in patients who are prescribed anticoagulant agents, both oral and parenteral due to concerns of haematoma. IM injections may cause bleeding, bruising, or hematomas.

  • Thus, Patients on anticoagulants should ideally avoid IM injections because of the risk of hematoma formation; this risk is expressed in anticoagulation treatment guidelines. IM injections may cause tissue injury and may also puncture small blood vessels in their way.

  • Worth to note, many studies have documented the relative safety of IM injections in anticoagulated patients. Some authorities say: Planned IM injections in patients on oral anticoagulation treatment can be undertaken by discontinuing the anticoagulation medication for a short period, such as 3 days, and then resuming the medication after the IM injection.

  • It has been suggested that if IM injections are required, sufficient pressure should be applied at the site of injection for a sufficient period of time to ensure that there is no leakage of blood into muscle tissue

  • The Green Book, UK: has explicit guidance in chapter 14a on the management of patients being offered the COVID-19 vaccination and who are also prescribed anticoagulants: “Individuals on stable anticoagulation therapy, including individuals on warfarin who are up-to-date with their scheduled INR testing and whose latest INR is below the upper level of the therapeutic range, can receive intramuscular vaccination. A fine needle (23 or 25 gauge) should be used for the vaccination, followed by firm pressure applied to the site without rubbing for at least 2 minutes (ACIP 2019). The individual/parent/ carer should be informed about the risk of haematoma from the injection.”

Taking anticoagulants or a bleeding disorder is not a contraindication to intramuscular injections, but the recipient needs to be aware that they may have increased bruising and be advised to apply pressure.

Ensure every operator managing the booking and reviewing of patients for the COVID-19 vaccination is made aware that confirming the individual uses anticoagulants does not exclude them from receiving the vaccine.

  • As increasing numbers of people are prescribed oral anticoagulants, for conditions such as atrial fibrillation, it is likely that a number will require a small volume intramuscular (IM) injection at some point.

 Factors that need to be considered in these cases include:

  • Is there an increased risk of adverse effects, such as bruising or haematoma?
  • Could the injection affect anticoagulant control?
  • Could the anticoagulant alter the effectiveness of the injection e.g., vaccines?

We do not have information at present about blood thinners and effectivity issues post vaccination.

  • Most of the published studies available on this subject relate to IM influenza vaccination in patients taking older anticoagulants, such as warfarin. Data are limited and some findings are contradictory. Over recent years there has been a wider uptake of the newer oral anticoagulants, apixaban, rivaroxaban, dabigatran and edoxaban, collectively named novel or direct oral anticoagulants (NOACs or DOACs), but there is very little published information about the risks of adverse effects with DOACs and IM injections.

  • CME INDIA Editor ‘TAKE HOME: No need of panic if your patient is on Anti-platelets, proceed for vaccination. If on anti-coagulants, defer the drug for 3 days if needed. Anyway, only problem patient may face is not very serious, it can be managed with proper technique and prior-assessment.

CME INDIA Tail Piece

Is Joint Aspiration or Injection Safe in Patients Taking Direct-Acting Oral Anticoagulants?

In a retrospective study of 1050 procedures, no bleeding complications occurred. This study demonstrates the safety of joint or bursa aspirations or injections in patients who are taking DOACs; risk for bleeding complications appears to be negligible.  Mayo Clin Proc 2017 Aug.


  4. Influenza vaccination and warfarin anticoagulation: a comparison of subcutaneous and intramuscular routes of administration in elderly men.Delafuente JC, Davis JA, Meuleman JR, Jones RA.Pharmacotherapy. 1998 May-Jun; 18(3):631-6.
  5. Royal Children’s Hospital, Melbourne, Australia, Clinical Practice Guideline on Anticoagulation Therapy. [Last accessed on 2015 Oct 12]. Available from: 
  6. Fox, E., Misko, J., Rawlins, M. et al. The risk of intramuscular haematoma is low following injection of benzathine penicillin G in patients receiving concomitant anticoagulant therapy. J Thromb Thrombolysis 50237–238 (2020).

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