Living with multiple sclerosis means learning which everyday triggers can worsen your symptoms or speed up disease progression. Some are well-established, like smoking and overheating. Others, like certain supplements marketed as immune boosters, carry risks that aren’t immediately obvious. Here’s what the evidence says about the most important things to watch for.
Smoking
If there’s one lifestyle factor with the clearest link to worse MS outcomes, it’s smoking. Smokers with MS are 2.72 times more likely to experience a relapse compared to non-smokers, and more than twice as likely to experience any form of disease activity. Beyond relapses, smoking increases the risk of MS progression by roughly 55%. These numbers make quitting one of the most impactful things you can do for long-term disease management, and the benefits apply whether you’ve been smoking for years or just started.
Heat and Overheating
Heat sensitivity is one of the most distinctive features of MS. When your core body temperature rises even slightly, nerve signals slow down along damaged pathways, temporarily worsening symptoms like vision problems, weakness, and poor balance. Research shows that a core temperature increase of just 0.6°C (about 1°F) is enough to measurably worsen visual symptoms. In some people, even skin warming alone can trigger problems like increased postural sway and motor difficulties without any change in core temperature at all.
This phenomenon, called Uhthoff’s phenomenon, limits participation in exercise, daily activities, and work for many people with MS. The good news is that it’s temporary and doesn’t represent actual disease progression. Practical strategies like drinking cold water and applying cooling packs to the skin have been shown to reduce symptom worsening even when core temperature still rises. Avoiding hot tubs, saunas, and prolonged direct sun exposure during peak heat are straightforward ways to prevent flare-ups.
High-Fat Diets
The relationship between dietary fat and MS activity has been studied for decades. One of the longest-running dietary studies in MS began in 1951, following 144 patients who agreed to limit saturated fat to under 20 grams per day. Those who stuck with the diet showed significantly less disability and lower mortality rates than those who didn’t, though the study lacked the controls needed to rule out other explanations.
More rigorous recent work has reinforced the pattern. A prospective study of 219 children and adolescents with MS found that for every 10% increase in the proportion of calories coming from fat, relapse risk rose by 56%. While the exact mechanism is still debated, the direction of the evidence consistently points toward keeping saturated fat intake low. Processed meats, full-fat dairy, fried foods, and baked goods made with butter or lard are the biggest contributors to saturated fat in most diets.
Immune-Boosting Supplements
MS is an autoimmune disease, meaning the immune system is already overactive and attacking the body’s own nerve coverings. Supplements marketed as “immune boosters” can theoretically make this worse. Echinacea is the most commonly flagged example. It has been shown to stimulate immune activity, which poses a real concern for anyone with an autoimmune condition. The effects of echinacea specifically on MS have not been studied, but the biological logic is straightforward: ramping up the system that’s already causing damage is not a good idea.
The same caution applies to elderberry, astragalus, and other herbal products sold for cold and flu prevention. These supplements can also interact with MS medications, so it’s worth checking with a pharmacist before adding anything new to your routine.
Live Vaccines on Certain MS Medications
If you’re taking a disease-modifying therapy that suppresses or alters your immune system, live-attenuated vaccines are generally contraindicated. The American Academy of Neurology recommends against live vaccines for people on immunosuppressive MS therapies because of the biologically plausible risk that a weakened but live virus could cause infection in someone whose immune defenses have been deliberately lowered.
The timing matters even after you stop treatment. For some therapies, the recommendation is to avoid live vaccines for two months after discontinuation. For others, the window extends to six months or until your immune cell counts recover. Common live vaccines include the nasal flu spray (the injectable flu shot is fine), the MMR vaccine, the chickenpox vaccine, and the yellow fever vaccine. Inactivated and mRNA vaccines don’t carry this risk, though your immune response to them may be weaker while on treatment.
Alcohol
Alcohol doesn’t directly trigger MS relapses in the way smoking does, but it compounds many of the symptoms you’re already managing. Balance problems and coordination difficulties are central features of MS, and alcohol impairs those same systems independently. Research on alcohol dependence and MS has documented that excessive sway during standing is a hallmark of alcohol misuse, and this instability can persist even after long periods of sobriety. When you layer alcohol’s effects on top of MS-related balance impairment, the combined result is a meaningful increase in fall risk.
Alcohol also worsens bladder dysfunction, disrupts sleep quality, and can interfere with medications. Moderate or occasional drinking may be fine for some people with MS, but paying attention to how even small amounts affect your specific symptoms is more useful than following general population guidelines.
Chronic Stress
The link between stress and MS flares has biological backing. When your body mounts a stress response, it triggers a cascade of hormones and signaling molecules that can dysregulate immune function. In people with MS, research has identified alterations in immune cells and inflammatory markers during periods of stress, and the body’s main stress-response systems, including the hormonal axis that controls cortisol release and the sympathetic nervous system, show measurable dysfunction in MS patients.
None of this means every stressful week will cause a relapse. But sustained, unmanaged stress appears to shift the immune environment in a direction that favors disease activity. Stress management isn’t just a wellness nicety for people with MS. It’s a practical tool for reducing flare risk. What works varies from person to person, but cognitive behavioral therapy, mindfulness-based approaches, and regular physical activity all have evidence behind them for stress reduction.
Overexertion During Exercise
Exercise is consistently recommended for people with MS, and avoiding it entirely is itself something to avoid. But pushing too hard can backfire, especially through worsening fatigue, which is already the most common and disabling MS symptom. The key is staying within a moderate intensity range.
In clinical studies of exercise for MS fatigue, effective programs generally kept heart rate between 40% and 75% of the predicted maximum and capped perceived exertion at “somewhat hard” on a standard effort scale. Programs that stayed within these boundaries had very low rates of adverse events. Falls were rare, reported in only two trials across a large body of research. A practical approach is to use the “talk test”: if you can carry on a conversation during exercise, you’re likely in a safe zone. If you can’t get a sentence out, dial it back. Building in rest days and planning activity for cooler parts of the day (to avoid compounding heat sensitivity) makes it easier to stay consistent without overdoing it.
Infections and Illness
Common infections are a well-known trigger for MS relapses. When your body fights off a virus or bacterial infection, the resulting immune activation can spill over into increased activity against your own nerve tissue. Epstein-Barr virus has received particular attention because of its deep connection to MS. Active EBV infection in immune cells has been identified in the brains of nearly all patients studied with secondary progressive or acute MS, and the immune cells that target EBV-infected cells can cross-react with the protective coating around nerves, directly causing damage.
While you can’t avoid every cold or flu, basic precautions like staying current on recommended (non-live) vaccines, practicing good hand hygiene, and treating infections promptly all reduce your exposure to a known relapse trigger.