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COVID Vaccine and Blood Clot Risks Explained

Know about covid vaccine and blood clot risks, understanding what it is, cause of blood clot, what should be done if you are concerned and lifestyle tips to reduce the blood clot risk.

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Written by Dr. D Bhanu Prakash

Reviewed by Dr. Vasanthasree Nair MBBS

Last updated on 30th Jul, 2025

Introduction 

The COVID-19 vaccines have played a crucial role in protecting millions of people from severe illness and hospitalization. However, like all medical treatments, vaccines can have rare side effects. One such concern that has been discussed is the potential risk of blood clots after receiving certain COVID-19 vaccines.

If you’re worried about this, you’re not alone. Many people have questions about vaccine safety, and it’s important to get clear, accurate information. In this article, we’ll explain what blood clots are, their connection (if any) to COVID vaccines, symptoms to watch for, and what you can do to stay safe.

Understanding Blood Clots

A blood clot is a clump of blood that forms when blood changes from a liquid to a gel-like state. While clotting is a normal process that helps stop bleeding when you’re injured, sometimes clots form inside blood vessels when they shouldn’t. This can block blood flow and cause serious health problems.

There are two main types of dangerous blood clots:

  • Deep Vein Thrombosis (DVT) – A clot in a deep vein, usually in the leg.

  • Pulmonary Embolism (PE) – A clot that travels to the lungs, which can be life-threatening.

Consult a top general practitioner for the best advice

Dr Syed Mateen Pasha, General Physician

Dr Syed Mateen Pasha

General Physician

2 Years • MBBS

Bengaluru

PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru

400

Do COVID-19 Vaccines Cause Blood Clots?

Most COVID-19 vaccines are very safe, and severe side effects are extremely rare. However, some vaccines (like AstraZeneca and Johnson & Johnson) have been linked to a very small risk of a specific type of blood clotting disorder called Thrombosis with Thrombocytopenia Syndrome (TTS).

The key facts for vaccine-related blood clots include:

  • Extremely rare – The risk is estimated to be around 1 in 100,000 to 1 in 250,000 doses.

  • More common in younger adults – Cases have been reported mostly in people under 60.

  • Different from usual clots – TTS involves both clotting and low platelet counts (cells that help blood clot).

Other vaccines, like Pfizer and Moderna (mRNA vaccines), have not been linked to this risk.

Symptoms to Watch For

If you’ve recently received a COVID-19 vaccine, be aware of the following symptoms, which usually appear within 4 to 28 days after vaccination:

  • Severe or persistent headache (not relieved by painkillers)

  • Blurred vision or confusion

  • Shortness of breath or chest pain

  • Leg swelling or pain (sign of DVT)

  • Unusual bruising or bleeding (due to low platelets)

If you experience any of these, seek medical attention immediately.

Who Is at Higher Risk?

While the overall risk is very low, some groups may have a slightly higher chance of developing TTS:

  • Women under 60 (though men can also be affected)

  • People with a history of blood clots or clotting disorders

  • Those with low platelet counts

If you fall into any of these categories, talk to your doctor before getting vaccinated.

What Should You Do If You’re Concerned?

  • Get the Right Vaccine – If you’re worried about blood clots, consider opting for mRNA vaccines (Pfizer or Moderna), which have no known link to TTS.

  • Stay Alert for Symptoms – Monitor yourself for any unusual signs in the weeks after vaccination.

  • Consult a Doctor – If you have a history of clotting disorders, discuss the best vaccine option for you.

  •  Don’t Delay Vaccination – The benefits of COVID-19 vaccination far outweigh the risks for most people.

 Lifestyle Tips to Reduce Blood Clot Risk

Even if you’re not at high risk, these habits can help maintain good circulation:

  • Stay active – Avoid sitting for long periods; take short walks.

  • Stay hydrated – Drink plenty of water to keep blood flowing smoothly.

  • Wear compression socks (if recommended by a doctor).

  • Avoid smoking – Smoking increases clotting risks.

When to See a Doctor?

If you experience any unusual symptoms after vaccination, don’t ignore them. Early detection and treatment can prevent serious complications.

Final Thoughts

The risk of blood clots from COVID-19 vaccines is extremely low, and vaccines remain one of the best tools to protect against severe COVID-19. Staying informed, recognizing symptoms early, and making healthy lifestyle choices can help keep you safe.

Consult Top Specialists

Dr Syed Mateen Pasha, General Physician

Dr Syed Mateen Pasha

General Physician

2 Years • MBBS

Bengaluru

PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru

400

Consult a top general practitioner for the best advice

Dr Syed Mateen Pasha, General Physician

Dr Syed Mateen Pasha

General Physician

2 Years • MBBS

Bengaluru

PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru

400

Dr. Gaddam Manoj, General Practitioner

Dr. Gaddam Manoj

General Practitioner

1 Years • MBBS

Hyderabad

Aaradhya clinic, Hyderabad

125

IMAGE
Dr. Syed Ismail Ali, General Practitioner

Dr. Syed Ismail Ali

General Practitioner

7 Years • MBBS

Hyderabad

Apollo 24|7 Clinic, Hyderabad

509

Dr. Madhuri Sai Sreepada, General Practitioner

Dr. Madhuri Sai Sreepada

General Practitioner

9 Years • MBBS

Hyderabad

BRIGHT SMILES MEDICARE & DENTAL CARE, Hyderabad

350

300

Dr. Karanam Kondalamma, General Practitioner

Dr. Karanam Kondalamma

General Practitioner

4 Years • MBBS

Hyderabad

KK Clinic, Hyderabad

313

Consult Top Specialists

Dr Syed Mateen Pasha, General Physician

Dr Syed Mateen Pasha

General Physician

2 Years • MBBS

Bengaluru

PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru

400

Dr. Gaddam Manoj, General Practitioner

Dr. Gaddam Manoj

General Practitioner

1 Years • MBBS

Hyderabad

Aaradhya clinic, Hyderabad

125

IMAGE
Dr. Syed Ismail Ali, General Practitioner

Dr. Syed Ismail Ali

General Practitioner

7 Years • MBBS

Hyderabad

Apollo 24|7 Clinic, Hyderabad

509

Dr. Madhuri Sai Sreepada, General Practitioner

Dr. Madhuri Sai Sreepada

General Practitioner

9 Years • MBBS

Hyderabad

BRIGHT SMILES MEDICARE & DENTAL CARE, Hyderabad

350

300

Dr. Karanam Kondalamma, General Practitioner

Dr. Karanam Kondalamma

General Practitioner

4 Years • MBBS

Hyderabad

KK Clinic, Hyderabad

313

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