The central nervous system (brain and spinal cord) controls all of your body's actions. When MS damages the myelin coating around the nerve fibres that carry messages to and from your brain, symptoms can occur in any part of your body.
There are many different symptoms of MS and they affect each person differently. Some of the most common symptoms include:
- extreme tiredness (fatigue)
- numbness and tingling
- blurring of vision
- problems with mobility and balance
- muscle weakness and tightness
Most people with MS only have a few of these symptoms and it is unlikely someone would develop all possible symptoms.
The symptoms are unpredictable. Some people's MS symptoms develop and increase steadily over time, while for others, they come and go periodically.
These periods when symptoms get worse are known as relapses. Periods when symptoms improve or disappear are known as remissions.
In around one in five cases of MS, the first noticeable symptom is problems with one of your eyes. You may experience:
- some loss of vision in the affected eye – this can range from mild to severe (total loss of vision occurs in one in 35 cases)
- colour blindness
- eye pain; usually made worse when moving the eye
- flashes of light when moving the eye
These symptoms are the result of optic neuritis, which is inflammation (swelling) of the optic nerve that transmits visual information to the brain. This normally only affects one eye.
Other visual problems that can occur in MS include:
- double vision
- eye pain in both eyes
- involuntary eye movements (usually from side to side), known as nystagmus
Abnormal sensations can also be a common initial symptom of MS. This can take the form of numbness or tingling in different parts of your body.
Muscles in your arms and legs may also feel unusually weak.
Muscle spasms and spasticity
If messages between your brain and muscles are disrupted, this can cause problems with muscle movements. It can cause muscles to contract tightly and painfully (spasm) or your muscles may also become stiff and resistant to movement, known as spasticity.
Around half of people with MS experience pain, which can take two forms:
- Neuropathic pain – caused by damage to the nerve fibres in the brain and spinal cord. It can be a stabbing pain, extreme skin sensitivity, or a burning sensation.
- Musculoskeletal pain – this is not caused directly by MS, but can occur if there is excess pressure on muscles or joints as a result of spasms and spasticity.
MS can affect balance and co-ordination. It can make walking and moving around difficult, particularly if you also have muscle weakness and spasticity. You may experience:
- ataxia – difficulty with co-ordination
- tremor – shaking of the limbs, which is rare, but can be severe
- dizziness and vertigo can happen late on and can make you feel as if your surroundings are spinning
Extreme tiredness (fatigue)
Feeling extremely tired (fatigue) is a common symptom of MS that many people describe as one of the most troublesome.
It is estimated that as many as nine out of 10 people with MS will experience episodes of fatigue.
People with MS have reported feeling an overwhelming sense of weariness where even the most simple physical or mental activity seems to be a tremendous struggle to carry out.
Fatigue may be worse in hot weather, after exercising, or during illness.
Problems with thinking, learning and planning
Around half of people with MS have problems with thinking, learning and planning (known as cognitive dysfunction). They may experience:
- problems understanding and using language
- a shortened attention span
- problems learning and remembering new things (long-term memory is usually unaffected)
- problems understanding and processing visual information, such as reading a map
- difficulty with planning and problem solving – people often report that they know what they want to do, but can’t grasp the method of how to do it
- problems with reasoning, such as mathematical laws or solving puzzles
Mental health issues
Around half of all people with MS experience at least one episode of depression at some point in their life.
It is unclear whether the depression arises from the damage to the brain caused by MS, or due to the stress of having to live with a long-term condition, or both.
Anxiety can also be a problem for people with MS, possibly due to the unpredictable nature of the condition.
Some people with MS can sometimes experience rapid and severe mood swings, suddenly bursting into tears, laughing or shouting angrily for no apparent reason.
MS can have an effect on sexual function.
Men with MS often find it hard to obtain or maintain an erection (erectile dysfunction). They may also find it takes a lot longer to ejaculate when having sex or masturbating, and may even lose the ability to ejaculate altogether.
For women, problems include difficulty reaching orgasm as well as decreased vaginal lubrication and sensation.
Both men and women with MS may find they are less interested in sex than they were before. This could be directly related to the MS, or it could be the result of living with the condition.
Bladder problems are common in MS.
They may include:
- difficulty emptying the bladder completely
- having to urinate more frequently
- having a sudden, urgent need to urinate which can lead to unintentionally passing urine (urge incontinence)
- having to get up frequently during the night to pass urine (nocturia)
Many people with MS have problems with their bowel.
Constipation is the most common problem, affecting around half of people with MS. They may pass stools much less frequently than normal, and find this difficult.
Bowel incontinence is less common but is often linked to constipation. If a stool becomes stuck, it can irritate the wall of the bowel, causing it to produce more fluid and mucus that can leak out of the anus (back passage).
Speech and swallowing difficulties
Around a third of people with MS experience difficulty chewing or swallowing (dysphagia) at some point. In some cases, speech may also become slurred, or difficult to understand.
However, for most people with MS, speech and swallowing symptoms are mild and only last for a few minutes at a time. They are often at their worst during a relapse.