Uhthoff's Phenomenon: What It Is and How Medications Can Trigger It

When your Uhthoff's phenomenon, a temporary worsening of neurological symptoms due to a rise in body temperature. Also known as Uhthoff's sign, it most often affects people with multiple sclerosis, a chronic condition where the immune system attacks the protective covering of nerves. Even a small increase in core temperature—like from a hot shower, exercise, or a fever—can make fatigue, blurry vision, or muscle weakness suddenly worse. The symptoms don’t mean your MS is getting worse; they’re just temporarily amplified by heat.

What makes Uhthoff’s phenomenon tricky is that it’s not just heat doing the work. Some medications can raise your body temperature or interfere with how your body regulates it. For example, drugs like anticholinergics, used for overactive bladder, Parkinson’s, and some psychiatric conditions block sweat production, making it harder to cool down. Others, like certain antidepressants, including SNRIs and tricyclics, can affect your body’s thermostat. Even common OTC painkillers like ibuprofen can sometimes mask early signs of overheating, letting the problem build unnoticed. If you have MS and are on any of these meds, you’re not just managing your disease—you’re managing a delicate balance with your environment and your pills.

It’s not about avoiding all heat or stopping your meds. It’s about recognizing the pattern. Keep a log: when do your symptoms flare? After a workout? After taking your evening pill? Did you just drink a hot coffee? Many people with Uhthoff’s phenomenon learn to adjust their routines—cool showers before bed, avoiding saunas, wearing cooling vests on hot days. Some even time their meds to avoid peak heat exposure. The goal isn’t to live in an air-conditioned bubble. It’s to take back control so heat doesn’t decide how you feel each day.

The posts below dive into the real-world side effects of medications that can make Uhthoff’s worse, how to spot hidden triggers, and what alternatives might help you stay cool—literally and figuratively. You’ll find practical advice on managing drug interactions, avoiding overheating from common prescriptions, and protecting your nervous system from everyday heat stress.