throat blood test explained

Overview

A throat blood test is a lab test that checks a sample of your blood for signs of infection or inflammation linked to throat problems. It can help tell the difference between a bacterial infection (like strep throat) and a viral infection (like glandular fever). The test looks for things like antibodies, white blood cell counts, or markers of inflammation.

This test is fairly common when a doctor suspects a more serious throat infection, like glandular fever (mononucleosis) or when a sore throat does not improve with simple care.

Anyone can have a throat blood test, but it is most often done in teenagers and young adults (common age for glandular fever) and in people with recurring or severe sore throats.

Symptoms

Common symptoms

• Sore throat that is very painful or lasts more than a week
• Swollen lymph nodes in the neck
• Fever over 38°C (100.4°F)
• Fatigue or feeling very tired
• White patches or pus on the tonsils

Symptoms in children

• Sore throat with difficulty swallowing
• Fussy or irritable behaviour
• Refusing to eat or drink
• Fever that does not improve

Symptoms in older adults

• Persistent sore throat with hoarseness
• Unexplained weight loss
• Swelling in the neck or throat that does not go away
• Difficulty breathing or swallowing

Causes

Main causes

• Bacterial infection, most commonly group A Streptococcus (strep throat)
• Viral infection, such as Epstein-Barr virus (glandular fever/mononucleosis) or adenovirus
• Inflammatory conditions like tonsillitis or pharyngitis

Risk factors

• Close contact with someone who has a sore throat or fever
• Age (teenagers and young adults are more likely to get glandular fever)
• Weakened immune system (due to illness, stress, or medications)
• Smoking or exposure to secondhand smoke

When to see a doctor

See a doctor urgently if:

• If you have difficulty breathing or swallowing
• If you have a high fever (over 39°C / 102°F) that does not respond to simple fever reducers
• If you cannot drink fluids due to throat pain

Book a routine appointment if:

• If your sore throat lasts more than a week
• If you have repeated sore throats that affect your daily life
• If you have a lump in your neck that does not go away

Diagnosis

Your doctor will first ask about your symptoms and examine your throat and neck. If they suspect a bacterial or viral infection that is not straightforward, they may order a blood test to get more information.

Tests that may be done

• Complete blood count (CBC) – checks for a high white blood cell count, which can mean infection
• Monospot test – looks for antibodies to the Epstein-Barr virus (glandular fever)
• C-reactive protein (CRP) – measures inflammation in the body

What to expect at your appointment

A small sample of blood is taken from a vein in your arm. It feels like a quick pinch. The sample is sent to a lab. You can usually go home right after, and results are available within a day. Your doctor will explain the results and what they mean for your treatment.

Treatment

Treatment depends on what the blood test shows. If it is a bacterial infection, antibiotics may be prescribed. If it is a viral infection, antibiotics will not help – the focus is on managing symptoms and letting your body fight the virus. Always follow your healthcare provider's advice.

Self-care at home

• Drink plenty of warm or cool fluids to stay hydrated
• Rest your voice and get extra sleep
• Gargle with warm salt water (half a teaspoon of salt in a glass of warm water)
• Use over-the-counter pain relievers like paracetamol or ibuprofen (follow the instructions on the label)
• Avoid smoking and smoky environments

Medical treatments

For bacterial throat infections, a course of antibiotics is often prescribed. It is important to take all the medication as directed, even if you start to feel better. For viral infections like glandular fever, treatment focuses on rest, pain relief, and staying hydrated. In some cases, your doctor may recommend steroid medicine to reduce severe swelling of the throat.

When is surgery considered?

Surgery is rarely needed for throat infections. In very rare cases of repeated severe tonsillitis that does not respond to treatment, a doctor may discuss removing the tonsils (tonsillectomy). This is only considered after other options have been tried.

Living with this condition

While recovering from a throat infection, take things slowly. Rest as much as you can, especially if you have glandular fever, which can cause fatigue for weeks. Avoid heavy physical activity until you feel better.

Lifestyle tips

• Avoid sharing drinks, food, or utensils to prevent spreading the infection
• Wash your hands regularly, especially after coughing or sneezing
• Use a separate towel and toothbrush until you are fully recovered

Diet and exercise

Eat soft, easy-to-swallow foods like soup, yogurt, and mashed potatoes. Avoid spicy or acidic foods that can irritate your throat. Gentle exercise is fine once your fever is gone and you have energy, but do not push yourself too hard.

Mental health and emotional wellbeing

Dealing with a long throat infection can feel frustrating and isolating, especially if you miss school or work. It is normal to feel low or anxious. Talk to friends or family about how you are feeling. If you feel very down or hopeless, reach out to your healthcare provider.

Prevention

You cannot always prevent a throat infection, but you can reduce your risk by practising good hygiene, such as washing your hands often and not sharing cups or utensils. Avoiding close contact with people who are sick also helps.

Vaccines

There is no vaccine for the most common throat infections (strep throat or glandular fever). However, the flu vaccine can help prevent flu-related sore throats. Talk to your doctor about which vaccines are right for you.

Screening programmes

There is no routine screening for throat infections. Blood tests are only done when symptoms suggest a specific infection that needs confirmation.

Complications

If left untreated

• Untreated strep throat can occasionally lead to rheumatic fever, which affects the heart and joints
• Glandular fever usually resolves on its own, but complications like an enlarged spleen or liver inflammation can occur
• Severe swelling of the throat can sometimes cause breathing difficulties

Long-term outlook

Most throat infections get better with rest and simple care. When treated properly, the risk of serious complications is very low. Even glandular fever, which can take several weeks to fully recover from, usually goes away without lasting problems. Your healthcare provider will monitor you to make sure you heal well.

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