There isn’t a simple test that can diagnose multiple sclerosis, and everyone’s experience of diagnosis is different. Neurologists use a set of guidelines called the McDonald criteria and a combination of your medical history, physical tests known as a neurological examination, blood tests, MRI scans and other tests to help to establish whether you have MS or not.
On this page we look at the tests you may undergo to get a diagnosis and why it can take some time to diagnose MS. We explore what a neurologist is looking for to make a diagnosis and what happens once your test results are in.
Who should I see if I'm experiencing symptoms associated with MS?
Most people will speak to their GP first if they’re affected by symptoms commonly seen in MS. Although your GP can’t diagnose MS themselves, they may be able to rule out other possible causes for your symptoms, and they can refer you to a neurologist if they agree your symptoms are neurological and might be MS. They are likely to refer you to a general neurologist at first, rather than an MS specialist neurologist.
If you’re experiencing very severe symptoms that come on rapidly, you may decide to go to the accident and emergency (A&E) department of your local hospital. If you are admitted, tests may be carried out at this stage if MS is suspected.
A diagnosis of MS can only be made by a neurologist. They use a set of international guidelines called the McDonald criteria to help them make an accurate diagnosis of MS as early as possible. At your first neurology appointment, they will take your medical history, carry out some simple physical neurological tests such as checking your reflexes, and may request some blood tests (NHS.UK).
Depending on what these initial tests show, your neurologist may then refer you for one or more further tests which will be carried out at a later appointment. This will always include an MRI scan of the brain, and in many cases a scan of the spinal cord will also be performed.
In some circumstances you may also need to have additional tests such as a lumbar puncture, evoked potentials, or an optical coherence tomography (OCT) scan.
You may hear the process of diagnosing MS being described as a ‘differential diagnosis’ or a ‘diagnosis of exclusion’. This means that a neurologist will want to rule out any other conditions that could be causing your symptoms before giving a diagnosis of MS.
Tests used in the diagnosis of MS
A variety of tests can be used to help diagnose MS. They may be used to look for characteristics that are typical in MS or to help rule out other conditions with similar symptoms to MS.
Medical history
Your neurologist will ask you a range of questions about your health. This may include questions about any illnesses or operations you’ve had in the past and any medications you take. You may be asked about the health of your close family members too. They might also ask about your diet and exercise routine.
It is important to tell your neurologist about any symptoms you’ve experienced in the past, as far back as your teenage years, even if they didn’t seem important at the time, were unexplained or explained away as a ‘virus’ or labyrinthitis (NHS.UK).
The next step will be for you to have some physical tests that make up the neurological examination. You will not have to take your clothes off as no intimate examination is needed. The tests are simple checks of your reflexes, vision, movement, strength, balance and coordination. They can indicate if, and where, there is any damage in the brain and spinal cord (central nervous system). You do not need to prepare ahead for these tests.
Watch consultant neurologist Nick Cunniffe demonstrate the tests involved in a neurological examination.
Consultant neurologist Nick Cunniffe demonstrates the physical tests involved in a neurological examination
Blood tests
Your neurologist will probably request that you have blood samples taken for testing. This may be done at your GP surgery or at a hospital phlebotomy clinic.
There isn’t currently a blood test that can diagnose MS, but blood tests may be able to rule out other conditions that have similar symptoms to MS. Common tests might include:
A full blood count to rule out infections and anaemia.
A C-reactive protein (CRP) test which measures inflammation levels.
Checking vitamin levels, especially vitamin B12 or folate deficiency (NHS.UK) which can result in symptoms such as fatigue, pins and needles, muscle weakness and problems with vision.
Checks for specific autoantibodies, such as antinuclear antibody (ANA) which can indicate an autoimmune condition such as lupus (NHS.UK) whose symptoms include muscle pain, fatigue, depression and anxiety.
Thyroid function tests to check for thyroid disorders – an underactive thyroid (NHS.UK) (hypothyroidism) can lead to symptoms such as fatigue, constipation, problems with concentration and memory, low mood and depression; whilst an overactive thyroid (NHS.UK) (hyperthyroidism) can cause anxiety, mood swings, fatigue and heat sensitivity.
Your neurologist may also request blood tests which are not diagnostic but will be important if you do receive a diagnosis of MS. This might include tests to see if you are immune to childhood illnesses, such as chickenpox, measles, mumps and rubella. Or to check if you have a latent hepatitis B or HIV infection – where the virus remains in your body but is not replicating or causing symptoms. Latent infections can become active again due to factors such as a weakened immune system or stress.
There is an increased risk of infection with some of the disease modifying drugs (DMDs) used in MS. So, depending on your results, you may need to be vaccinated, or have a latent infection treated, before you can start a particular DMD.
The next step will be a referral for a magnetic resonance imaging (MRI) scan of your brain. Your neurologist may also ask for an MRI scan of your spine if they think it is appropriate.
A brain MRI scan can show typical features of MS and combined with the medical history and neurological examination, secure a diagnosis as early as possible. It can also help rule out other conditions that have similar symptoms to MS but look different on a scan.
The main reason to do an MRI scan is to look for evidence of lesions, which may also be referred to as scars or scarring. The type of scan that is most used in diagnosis uses settings where lesions show up as white patches and indicate where the myelin sheath has been damaged or destroyed.
Watch research radiographer Victoria Lupson explain how to prepare for an MRI scan and what is involved.
Research radiographer Victoria Lupson explains what an MRI scan involves
Recently it has been found that there are two types of lesions that are very specific to MS – the central vein sign (CVS) and paramagnetic rim lesions (PRLs).
Central vein sign – MS lesions often have a blood vessel running through the middle of them which can be seen on an MRI scan. Detecting lesions with the CVS on an MRI scan can help differentiate MS from other conditions with similar symptoms, or lesions which are due to ageing.
Paramagnetic rim lesions – these lesions have a very distinctive dark rim of iron around their edge.
If lesions with the central vein sign or a paramagnetic rim are seen on an MRI scan, it can help make the diagnosis of MS quicker and further tests may not be needed.
You might be asked to have an additional scan which involves injecting a contrast dye called gadolinium into your veins. This can help differentiate between any new active lesions or lesions which are becoming larger, and areas of older scarring. But this is not always necessary.
Find out how MRI scans help diagnose MS, what neurologists look for and why you can’t interpret your own scan with consultant neurologist Will Brown.
Consultant neurologist Will Brown explains how MRI scans can help diagnose MS
Lumbar puncture
If an MRI scan does not give enough evidence to make a diagnosis, you may have a lumbar puncture (also known as a spinal tap). This involves a needle being inserted into your lower back between the bones in your spine, to take a small amount of cerebrospinal fluid (CSF) which is then sent for analysis. It is not unusual to feel anxious about having a lumbar puncture.
Watch consultant Nick Cunniffe explain how to prepare for a lumbar puncture and what is involved.
Consultant neurologist Nick Cunniffe demonstrates a lumbar puncture
Your CSF sample will be examined for evidence of inflammation. This may be seen as a higher number of a type of white blood cells known as lymphocytes in your CSF than expected. Or there may be increased amounts of antibodies in the fluid, which can be detected in one of two ways:
by looking for oligoclonal bands – this is the test that has been carried out historically, or
measuring levels of kappa free light chains – a newer test which is quicker and easier to perform.
MS damage can slow down the transmission of nerve signals. Evoked potential tests measure the speed of messages along the sensory nerves to your brain. They can be used in the diagnosis of MS to detect damaged nerve pathways by identifying even very small delays in the transmission of messages.
An optical coherence tomography (OCT) scan is an imaging test which is widely used by optometrists at your local opticians and specialist eye doctors (ophthalmologists). Light waves are used to scan the eye to create a picture of the nerve fibre layers of the retina at the back of the eye. This test is very sensitive at detecting any thinning of the retinal nerve layer.
OCT is routinely used to detect eye problems associated with diabetes and age-related macular degeneration. It can also help diagnose MS if you’ve experienced problems with your eyes or vision, such as optic neuritis. If the nerve at the back of the eye (optic nerve) is damaged by MS, it can cause thinning of the retinal nerve layer. So, like MRI scans and visual evoked potentials (VEPs), OCT can be used to establish if the optic nerve has been damaged.
Watch senior ophthalmic technician Riddhima Gautam perform an OCT scan and consultant neurologist Nick Cunniffe explain what the scan is looking for.
Find out how an OCT scan can be used to help diagnose MS
How long does it take to get an MS diagnosis?
For some people it can be a relatively quick process, especially if you experience severe symptoms that are typical for MS and require hospital admission. For others the route to diagnosis can take longer. It can take time to get answers because MS is unique for everyone affected and can present differently. It can also take time to get a diagnosis because many of the symptoms seen in MS are also common in other health conditions.
This means that it is difficult to estimate how long diagnosis might take. For some people it may only take days or weeks from when you first start to have symptoms investigated, but for most people it will take months. Some people may even go several years before a diagnosis can be made.
Why is MS sometimes difficult to diagnose?
MS can be difficult to diagnose as there isn’t a simple test that can tell you if you have MS or not, and the symptoms of MS are not unique to the condition.
The McDonald criteria for diagnosing MS are regularly reviewed and updated with the aim of making an accurate diagnosis of MS as quickly as possible. They were first developed in 2001, with the most recent update in 2024. Advances in technology and our understanding of MS means that for most people diagnosis is becoming increasingly straightforward. However, there are still some circumstances where it can be more difficult.
Some MS symptoms are very non-specific, which means that early signs of MS may be overlooked either by you or your GP. This is especially true for symptoms such as fatigue, or sensory symptoms like numbness and tingling. You might put them down to something else, like being tired due to caring responsibilities, work, or not sleeping well. Or you may assume you’ve slept or sat awkwardly on a limb or have a trapped nerve. If a symptom only happens once, or only lasts for a short period of time, you may forget about it and only realise its importance later.
MS can also be more difficult to diagnose if you’re older. This is because it can be difficult to distinguish between the normal changes seen in the brain as you age and MS lesions. They both appear as bright white spots or patches on the main type of MRI scan that is used to help diagnose MS. Other conditions, such as migraine (NHS.UK), can also result in lesions in the brain.
It can be harder to make a diagnosis of MS if the scans do not show typical lesions, or if there are no, or very few lesions in the brain, but some in the spinal cord. Often the neurologist will want to repeat scans after a period of waiting, to see if the picture becomes more typical.
Looking after yourself while you wait for your results
The period between having tests done and getting your results can be an unsettling time. The following are some suggestions for places to seek support for your physical and mental health during this time.
You don’t need a diagnosis for support with managing any ongoing symptoms. Your GP may be able to prescribe medication that can help or refer you to specialist support, such as a physiotherapist or continence services, if appropriate.
Listen to our Limbo land podcast where consultant neurologist Emma Tallantyre shares her insights on how to manage during this period.
Reach out to our helpline team if you’ve got questions about MS. Talking things through can help you feel more in control.
What happens when you get your results?
Ideally, your results will be sent to your neurologist. They will make an appointment to discuss them with you and explain what they mean.
Sometimes your results might be sent in a letter or be available on an online portal, such as the NHS App, before you see your neurologist. If this happens, it is best not to try and interpret the results yourself as this could lead to unnecessary worry. Instead write down any questions you might have about anything you’ve read that you don’t understand to take to your appointment with you. While you wait for your appointment try to stay calm, stick with your normal routine and keep yourself busy. It can be tempting to slip into relying on unhealthy foods and not exercising when you’re facing uncertainty, so try to eat well (NHS.UK) and get some exercise (NHS.UK) if you can.
What happens if tests confirm MS?
What happens next will depend on several factors. Everyone is affected by MS differently and the way MS teams work varies across the UK. In some centres, you may see an MS specialist nurse immediately after your neurologist has talked through your results and given you your diagnosis, but it is more usual for your neurologist to make you an appointment to see them several weeks later. This can give you some time to think about any further questions you might have.
Not all areas have an MS specialist nurse, if this is the case where you’re being cared for you might be managed by your GP or another member of your MS team.
Depending on which type of MS you have been diagnosed with, your neurologist may suggest a follow-up appointment to discuss disease modifying drugs (DMDs) with you. Ideally, this will be within a few weeks of your MS diagnosis. DMDs don’t treat individual symptoms and they’re not a cure for MS. They try and alter how your MS develops over time, for example by reducing the number and severity of any relapses, limiting any new inflammation in the brain and spinal cord and some can help delay the progression of disability.
It is possible that you might not get a diagnosis of MS. This can happen if tests have been inconclusive or results aren’t what would typically be expected for MS. If this happens, your neurologist may:
suggest a period of ‘watching and waiting’ to see how your symptoms develop. They may suggest a further MRI scan in another three, six or 12 months, depending on circumstances. They should tell you how best to get back in touch if you have further symptoms before then. While this can be frustrating, they will want to be sure that it is MS and not another condition, so you don’t start on any medication unnecessarily
refer you for further neurophysiology tests, such as nerve conduction tests and electromyography (EMG) (NHS.UK). These are tests that can help identify problems with peripheral nerves and muscles. They are often helpful in diagnosing issues such nerve injuries, compressed nerves or peripheral neuropathy. They are also helpful for diagnosing conditions such as motor neuron disease and myasthenia gravis.
If your neurologist thinks you are experiencing neurological symptoms but you don’t have signs of any physical changes in your brain or nerves, they may refer you for further investigations to see if symptoms could be due to functional neurological disorder (FND). This is a condition where the brain doesn’t process nerve signals correctly and this faulty processing of information leads to the symptoms of FND, many of which overlap with those of MS.
Your neurologist may refer you back to your GP, or a specialist in another field, if they do not think your symptoms are neurological.
Where to get support
When you receive your diagnosis, your neurologist should tell you who you’ll see next and when. If this does not happen, and you do not hear within a month, contact your neurologist’s secretary or MS specialist nurse.
Who you see, and how often, will depend on your MS and how your MS service works. Read more about getting support from your MS team, friends and family, and the MS community.
Our free, confidential helpline is available Monday to Friday 10am to 4pm to answer any questions you may have. Or you can email your questions to: ask@mstrust.org.uk
Do get in touch.
Find out more
McDonald criteria – our comprehensive page on the guidelines used to diagnose MS
Lumbar puncture – our page with more information on using lumbar puncture to diagnose MS
What else might it be? (NICE) – information from the National Institute for Health and Care Excellence (NICE) on other conditions that can mimic MS
References
Montalban X, et al. Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria. Lancet Neurology 2025;24(10):850–865. Summary (link is external)
Clark KA, et al. Early MRI features of new paramagnetic rim lesions in multiple sclerosis. Annals of Neurology 2023;94(4):736-744. Full article (link is external)
Cambridge University Hospitals NHS Foundation Trust. Optical coherence tomography (OCT) and photography clinic with virtual review. [Accessed 18 December 2025] Full article (link is external)
Cleveland Clinic. Optical coherence tomography (OCT) in the diagnosis and management of MS. [Accessed 18 December 2025] Full article (link is external)
Contains introductory information that may be helpful if you have been recently diagnosed with MS. It covers what MS is, what happens after you’re diagnosed, preparing for appointments with health professionals and how to live well with MS.
