Feeling unwell for days or weeks at a time can be unsettling, particularly when there is no clear explanation. At London Blood Tests, many patients contact us because they are feeling sick all the time or experiencing ongoing digestive discomfort, and want to understand whether blood testing could help identify an underlying cause. In these situations, carefully selected blood tests for nausea and abdominal pain may provide useful clinical insight rather than reassurance alone.
Nausea can present in different ways. Some people describe nausea for no reason, while others notice patterns such as nausea after eating, nausea in the morning, or persistent morning nausea. It may also occur alongside broader symptoms like dizziness and nausea, extreme fatigue nausea, or episodes of unexplainable nausea that affect concentration, appetite, and energy levels. Although nausea and stress can play a role, persistent or worsening symptoms should be assessed more thoroughly.
Blood testing allows clinicians to assess key systems that may influence nausea, including inflammation, liver and kidney function, electrolyte balance, thyroid activity, and blood sugar regulation. Initial investigations often include a full blood count test and inflammatory markers such as a CRP blood test. Depending on individual symptoms, further tests may be appropriate to build a clearer picture. This guide explains how these blood tests are used, what they may help identify, and when further medical review is recommended.
Core blood tests used for nausea and abdominal pain
When investigating ongoing symptoms, clinicians usually take a broad but structured approach. For patients arranging blood tests for nausea and abdominal pain, this means assessing multiple systems at the same time rather than relying on a single marker. At London Blood Tests, this approach is reflected in comprehensive testing options such as our Nutritional Health Profile, which includes many of the markers commonly used when nausea is persistent or unexplained.
Initial screening often begins with a full blood count test, which helps assess overall blood health and may highlight infection, inflammation, or anaemia, all of which can contribute to nausea, weakness, or feeling generally unwell. Inflammatory activity is commonly reviewed using a CRP blood test, which measures C-reactive protein and can indicate whether the body is responding to an underlying inflammatory process.
Digestive and abdominal symptoms frequently prompt liver and protein assessment. A liver function blood test is used to evaluate markers linked to liver health, while an albumin blood test helps assess protein balance, nutritional status, and liver function. Abnormal liver function results can be associated with nausea, bloating, or discomfort after eating.
Pancreatic involvement may be considered when nausea is accompanied by upper abdominal pain or worsens with food intake. In these cases, a lipase blood test can help assess pancreatic enzyme activity.
Hydration status and mineral balance are also important. A urea & electrolytes test allows clinicians to review urea and creatinine levels alongside electrolytes such as sodium, potassium, and chloride. Abnormal results on a urea blood test, creatinine blood test, or electrolyte measurements can contribute to nausea, dizziness, and fatigue, particularly if vomiting or reduced fluid intake is present.
Hormonal and metabolic factors are assessed through thyroid and glucose testing. A thyroid stimulating hormone blood test, together with free thyroid hormone measurements, is commonly used when nausea is associated with fatigue, weight changes, or temperature sensitivity. Blood sugar regulation is reviewed using a glucose blood test, with longer-term trends assessed through an hba1c blood test, as unstable glucose levels may contribute to nausea and low energy.
Because nausea is often linked to nutritional imbalance, vitamin and mineral status is also relevant. Tests such as ferritin, vitamin B12, folate, magnesium, calcium, and zinc are frequently included in broader profiles, helping to identify deficiencies that may contribute to ongoing symptoms.
By combining these markers, comprehensive testing provides a clearer overview of how the body is functioning as a whole. For many patients, a broader panel such as the Nutritional Health Profile offers a practical way to assess multiple potential contributors to nausea in one appointment, rather than testing individual markers in isolation.
Blood tests based on associated symptoms
Nausea is rarely a standalone symptom, and understanding what else is happening in the body often helps guide appropriate testing. People attending for a blood test for nausea frequently report additional symptoms that shape how results are interpreted and which markers are most relevant.
When nausea is accompanied by low energy or exhaustion, patterns such as extreme fatigue nausea may suggest a broader systemic issue rather than a short-term illness. In these cases, blood testing focuses on identifying potential contributors that may affect energy levels, including inflammation, metabolic balance, or nutritional status.
Balance-related symptoms are also common. Experiences such as feeling dizzy and nausea may point towards fluid or electrolyte imbalance, blood sugar fluctuations, or dehydration. Reviewing these markers together can help explain why symptoms worsen with movement, standing, or changes in posture.
Digestive timing provides further clinical clues. Some people notice nausea after eating, while others struggle with ongoing nausea and bloating, which may be linked to digestive strain or metabolic changes. By contrast, nausea in the morning or persistent morning nausea can be associated with blood sugar regulation, hormonal patterns, or nutritional factors, particularly when symptoms improve later in the day.
Nausea may also overlap with head-related symptoms. Individuals reporting fatigue and nausea and headache or head pain nausea fatigue often benefit from blood tests that assess inflammation and glucose balance, as these factors can contribute to headaches when combined with nausea and tiredness.
In many cases, people seek testing simply because they are feeling sick without a clear explanation. When symptoms persist or feel disproportionate to everyday triggers, using blood tests to look at the body as a whole can help clarify whether there is a measurable imbalance or whether further clinical assessment is required.
What blood tests can and cannot explain
Some people seek testing because nausea is accompanied by more complex symptom patterns rather than occurring on its own. For example, combinations such as fatigue and nausea and headache or head pain nausea fatigue can suggest that nausea is part of a broader systemic issue rather than a purely digestive one. In these situations, blood tests may help identify contributing factors linked to inflammation, metabolic stress, or nutritional imbalance.
Nausea that occurs alongside balance symptoms, such as feeling dizzy and nausea, may raise questions about hydration status, mineral balance, or blood pressure regulation. Blood testing can sometimes highlight abnormalities that help explain why these symptoms occur together, particularly when they worsen with movement or positional change.
Digestive timing also plays an important role. Symptoms such as nausea after eating or nausea and bloating may point towards digestive strain or impaired processing of nutrients, while morning nausea can sometimes be associated with metabolic or hormonal patterns rather than acute illness. Blood tests can help assess whether these patterns are linked to measurable changes in the body.
It is also important to recognise that blood tests have limits. Some people experience unexplainable nausea or ongoing nausea for no reason, where standard blood results fall within normal ranges. This does not mean symptoms are insignificant, but rather that the cause may lie outside what blood testing alone can detect, such as functional digestive conditions or nervous system responses.
Blood tests are therefore best used to support clinical decision-making, helping to rule out medical causes, identify contributors that can be addressed, and guide whether further investigation or specialist input may be appropriate.
When thyroid testing is relevant
In some cases, nausea is linked to how the body regulates energy and metabolism rather than digestion alone. When symptoms persist without a clear trigger, thyroid assessment may help clarify whether hormonal imbalance is contributing to ongoing nausea, fatigue, or changes in appetite.
Initial evaluation often begins with a TSH test, which helps assess how the thyroid gland is being regulated. Where symptoms suggest a more detailed assessment is needed, measuring active thyroid hormones can add useful context. A free t4 test reflects circulating thyroxine levels, while a free t3 test looks at the hormone most directly involved in metabolic activity.
Reviewing these markers together can help determine whether thyroid-related imbalance may be contributing to symptoms and whether further clinical assessment or follow-up testing is appropriate.
When nausea needs urgent medical attention
While nausea is often mild and self-limiting, there are situations where it should not be managed with blood testing alone. If symptoms are severe, sudden, or worsening, urgent medical assessment is essential before arranging a blood test for nausea.
You should seek urgent medical care if nausea is accompanied by severe or persistent abdominal pain, chest pain, confusion, fainting, or signs of significant dehydration. Ongoing vomiting, an inability to keep fluids down, or symptoms that escalate rapidly should also be assessed promptly.
Nausea combined with neurological or balance symptoms, such as sudden dizziness and nausea or new weakness, requires immediate attention, particularly if symptoms are severe or appear without warning. Similarly, nausea associated with high fever, a stiff neck, or severe headache should not be investigated through routine blood testing alone.
Blood testing can play a role once urgent causes have been excluded, helping to assess recovery or identify contributing factors. However, in emergency situations, hospital-based assessment, imaging, or specialist care may be required before any outpatient investigations are considered.
If you are unsure whether your symptoms are urgent, it is always safer to seek immediate medical advice. Blood tests are most appropriate when symptoms are stable, ongoing, and not associated with red-flag features.
Take the next step
Persistent nausea can be difficult to ignore, especially when symptoms linger or feel unexplained. Blood testing can help provide clarity by checking for common medical causes and guiding next steps when symptoms do not resolve on their own.
If nausea has become ongoing or disruptive, booking blood tests for nausea and abdominal pain can help you move forward with confidence. You can choose individual tests or a broader option such as our Nutritional Health Profile, depending on your symptoms and needs.
View available blood tests or book your appointment with London Blood Tests today.