Some people with multiple sclerosis (MS) experience spells of fainting (syncope) or blacking out (temporary loss of vision and consciousness). These may be related to extreme dizziness and vertigo (feeling off-balance), or they may have other causes. If you’re living with MS and experiencing these symptoms, it’s important to understand what could be going on so you can find the best treatment for you.

Here is what you need to know about fainting or blacking out with MS, including what these symptoms may feel like, what causes them, and how they can be managed.

What Does Fainting or Blacking Out With MS Feel Like?

Fainting and blacking out are not among the more common symptoms of MS. However, a number of MyMSTeam members have described episodes. As one shared, “I experienced what my doctors called syncope after standing — total blackout!” “I suffer from random blackouts,” wrote another member.

Some people deal with episodes repeatedly, over an extended period. “I have blacked out at least five or six times,” one member shared. “The last time, I was out cold on the bathroom floor for about five hours.”

Fainting can prompt the need for emergency medical help. “I had a drop-down blackout,” a member explained. “I slammed my brain and hit my skull. I didn't wake up until I was in the hospital.”

For some MyMSTeam members, episodes of fainting or blacking out came on quickly, seemingly out of nowhere. For others, these episodes occurred alongside dizziness or vertigo that they’d been experiencing for a while. As one member wrote, “The dizziness I’ve been dealing with for a year or so has become really bad the last couple of months. Tonight is the first time that I blacked out and fell on the floor.”

Fainting and blacking out can be serious, indicating that something significant is going on in your body. Although fainting can have a number of causes, many can be traced back to MS.

What Causes Fainting and Blacking Out in MS?

MS is an autoimmune disease in which the immune system mistakenly attacks healthy tissues in the central nervous system (CNS), which includes the brain and spinal cord. Lesions, or areas of damaged tissue, then form on the nerves’ protective myelin coating (a process referred to as demyelination).

Fainting and blacking out in MS may be caused by new or growing MS-related lesions. It also can be caused by autonomic dysfunction (also known as autonomic failure), which results when the autonomic nervous system (ANS) does not work appropriately. The ANS regulates unconscious body functions and is responsible for helping people maintain balance. Autonomic dysfunction can lead to falls among people with MS.

In some cases, however, blacking out and fainting may stem from factors unrelated to MS.

Orthostatic Intolerance

Orthostatic intolerance (or orthostatic dysregulation or dysfunction) refers to a drop in blood pressure after a change in body position (most often going from lying or sitting to standing). This can lead to passing out, as well as hot flashes, heart palpitations, weakness, sweating, nausea, and more. One of the better-known forms of orthostatic dysregulation is postural orthostatic tachycardia syndrome (POTS).

Up to 63 percent of people diagnosed with MS also show signs of orthostatic dysregulation, which could cause fainting. In a study of nine people with POTS and a history of MS, all either passed out or nearly passed out.

People with MS are more likely to experience orthostatic dysregulation because of demyelination. The lesions caused by demyelination get in the way of the electrical messages the nerves are trying to pass to various parts of the brain. Lesions in the CNS areas that control heart function, lung function, and blood pressure could cause orthostatic dysregulation.

Epileptic Seizures

Epilepsy is a bit more common in people with MS than it is in the general population. Researchers are not sure why MS is linked with epilepsy and seizures. However, it is likely related to the different ways demyelination caused by MS affects the brain.

Multiple types of seizures are possible in people living with MS and epilepsy. Though not all seizures lead to blacking out, some can cause total loss of consciousness.

At least one MyMSTeam member said they’d had seizures that led to blackouts: “I’ve had a few and saw a specialist in epilepsy, and he said it was my MS,” the member wrote.

Medications

Some people diagnosed with multiple sclerosis experience dizziness and vertigo as a side effect of certain medications they are taking, whether for MS or another condition. Anytime dizziness gets too bad, it can cause fainting. Thus, it’s important to work with your neurologist and other health care professionals to get medical advice and find treatments that don’t cause adverse side effects.

Other Potential Causes of Fainting and Blacking Out

Fainting and blacking out can result from conditions unrelated to MS or its symptoms. These causes include:

• Use of illicit drugs
• Heart conditions
• Stress
• Problems with an artery in the neck

People may also faint because of:

• Skipping too many meals in a row
• Overdoing physical activity, especially when it’s hot and humid
• Becoming dehydrated

How To Manage Fainting and Blacking Out With MS

It’s a good idea to talk with a doctor anytime you faint, especially when you are also living with MS. Your neurologist may be able to help you determine what caused your fainting and make sure the help you get is compatible with your MS treatments.

Get immediate medical care if your fainting occurs with any of the following symptoms, which can be signs of a more serious underlying issue:

• Confusion
• Incoherent or slurred speech
• Blurry vision
• Shortness of breath
• Bladder or bowel control problems
• Chest pain
• Irregular heartbeat

Treat Any Underlying Conditions

If your neurology team finds an underlying condition, such as POTS or epilepsy, it’s important to treat these effectively. A number of therapeutic options are available, and your doctor will help you find one that is right for you. These treatments should control or eliminate the fainting and blacking out you experience.

Stand Up Slowly

Several MyMSTeam members note that standing up slowly helps them deal with orthostatic dysregulation problems. One member explained, “My doctor diagnosed it as ‘orthostatic hypotension.’ Not much to do for it except always remember to get up very slowly.” Another added, “I haven’t had another blackout but keep coming close — just stand up slower.”

This won’t eliminate the problem, but it can help you manage it until a suitable treatment is found.

Take Care of Yourself

If you faint or black out regularly — whether or not an underlying condition is involved — taking time for self-care can help you avoid the worst of these episodes. Make sure you eat and drink enough and that you don’t get overheated when it’s warm outside. Since these are all common causes of fainting, caring for yourself well may help you avoid these episodes.

Know What To Do When You Feel Faint

If you feel faint, take a few steps to avoid blacking out. Tensing your body can help get blood and oxygen flowing to the brain. Try crossing your legs or squeezing them together. You can also tense your torso and arms and even squeeze your hands into fists.

If you’re standing, sit down so you don’t fall and potentially injure yourself. This can also help equalize your blood pressure. Put your head between your legs to help your brain get the blood it needs to retain consciousness.

Find Your Team

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. On MyMSTeam, more than 186,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.

Do you struggle with fainting or blacking out? Are you wondering if this is associated with your MS? Share your thoughts or questions in the comments below or by posting on MyMSTeam.