Blood test
Informed by recognized medical guidance
Overview
A blood test is a medical test that checks your health by taking a small sample of blood from your body. The sample is sent to a lab to measure things like your red and white blood cells, cholesterol, blood sugar, or signs of infection or disease.
Key facts
- Blood tests are one of the most common and safest medical tests.
- They can help diagnose many conditions, from anaemia (low iron) to diabetes and infections.
- Results usually take a few hours to a few days, and your doctor will explain what they mean.
Yes, blood tests are extremely common. Most people will have several blood tests in their lifetime, often as part of a routine check-up or to investigate symptoms.
Anyone can need a blood test at any age. They are used for people of all backgrounds and health statuses.
Symptoms
- If you have symptoms like severe chest pain, trouble breathing, sudden weakness on one side of the body, or heavy bleeding that won’t stop – call your local emergency number immediately.
- ⚠If you have a high fever that does not go down, severe pain anywhere, or you feel faint or very weak after a blood test, contact your doctor or go to an urgent care centre.
Common symptoms
- Feeling very tired or weak
- Unexplained weight loss or gain
- Frequent infections or fevers
- Persistent bruising or bleeding
- Changes in appetite or thirst
Symptoms in children
- Poor growth or weight gain
- Frequent illnesses
- Pale skin or easy bruising
- Unusual tiredness or irritability
Symptoms in older adults
- Sudden confusion or memory problems
- Unexplained falls or dizziness
- Loss of appetite or weight loss
- Fatigue that does not improve
Causes
Main causes
- Infection or inflammation in the body
- Chronic conditions such as diabetes, kidney disease, or anaemia
- Side effects of certain medications or treatments
- Hormonal imbalances or thyroid problems
- Dietary deficiencies (e.g., low iron or vitamin levels)
Risk factors
- Family history of certain diseases
- Being overweight or having an unhealthy diet
- Smoking or drinking too much alcohol
- Not getting enough exercise
- Taking medicines that affect blood counts or clotting
When to see a doctor
See a doctor urgently if:
- If you have severe symptoms that worry you, such as chest pain, shortness of breath, or fainting – call emergency services.
Book a routine appointment if:
- As part of a regular check-up, especially if you have a chronic condition like high blood pressure or diabetes.
- If you are planning a pregnancy or have certain risk factors.
- If your doctor recommends one to monitor a health condition or treatment.
Diagnosis
A blood test is a diagnostic procedure. A healthcare professional draws a small amount of blood from a vein in your arm (or sometimes a finger prick). The sample is sent to a laboratory for analysis.
Tests that may be done
- Full blood count (FBC) – checks red and white blood cells and platelets
- Lipid profile – measures cholesterol and fats in your blood
- Blood glucose test – checks blood sugar levels
- Liver function tests – checks how well your liver is working
- Kidney function tests – checks how well your kidneys are working
- Thyroid function tests – measures thyroid hormone levels
- Iron studies – checks iron levels in your blood
What to expect at your appointment
You may be asked to fast (not eat or drink anything except water) for 8–12 hours before some tests. The blood draw takes just a few minutes. You might feel a small pinch, and there may be a bruise afterwards, but it usually heals quickly. Your doctor will discuss your results with you.
Treatment
Treatment is not for the blood test itself, but for the condition the test helps find. Depending on the results, your doctor may recommend lifestyle changes, medicines, or further tests. Always follow your healthcare provider’s advice.
Self-care at home
- Prepare for the test as instructed (e.g., fasting if needed)
- Drink plenty of water before the test (unless told not to) – it can make veins easier to find
- Wear a short-sleeved shirt or loose clothing to make the arm accessible
- After the test, eat a light snack and rest if you feel faint
Medical treatments
If your blood test shows a problem, your doctor may suggest treatments such as dietary changes, supplements, prescription medicines, or referral to a specialist. Never start or stop any treatment without talking to your doctor.
When is surgery considered?
A blood test alone rarely leads directly to surgery. However, abnormal results might point to a condition that requires a surgical procedure – for example, a high PSA (prostate-specific antigen) may lead to further tests like a biopsy. Your doctor will explain your specific situation.
Living with this condition
If you have a condition that requires regular blood tests, you will get used to the routine. Keep a record of your test dates and results, and ask your doctor what the numbers mean for your health.
Lifestyle tips
- Eat a balanced diet with plenty of fruits, vegetables, and whole grains
- Stay active with regular exercise – aim for at least 150 minutes of moderate activity per week
- Get enough sleep and manage stress through relaxation techniques or hobbies
- Avoid smoking and limit alcohol intake
Diet and exercise
Healthy eating and regular exercise can help improve many blood test results, such as cholesterol and blood sugar levels. Your doctor or a dietitian can give you personalised advice based on your results.
Mental health and emotional wellbeing
Waiting for blood test results can cause anxiety. It is normal to feel nervous. Talk to your doctor about your concerns, and remind yourself that most results are reassuring or lead to simple treatments.
Prevention
Blood tests themselves do not need to be prevented. They are a tool to prevent or catch diseases early. However, you can help keep your blood test results healthy by maintaining a balanced diet, staying active, and avoiding smoking and excessive alcohol.
Complications
If left untreated
- If abnormal blood test results are ignored, underlying conditions like high cholesterol, diabetes, or infection can worsen.
- Untreated anaemia can lead to severe fatigue and heart problems.
- Uncontrolled high blood sugar can damage nerves, kidneys, and eyes.
- Delaying treatment for infections can allow them to spread to the bloodstream (sepsis), which is life-threatening.
Long-term outlook
The good news is that most conditions found through blood tests can be managed or cured, especially when caught early. Regular check-ups and following your doctor’s advice give you the best chance for a healthy future.
Find support
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 16, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.