Have you ever noticed that half of your body felt different from the other — like the left side was hotter, sweatier, or more uncomfortable than the right? Perhaps this sensation occurred during the night, or maybe it took you by surprise while you were going about your day. What might cause this uneven feeling, and how can you manage it?

If you’re living with systemic lupus erythematosus (SLE, sometimes called lupus), an autoimmune disease that affects many organs, puzzling symptoms like one-sided heat can sometimes happen. In this article, we’ll explore why someone with lupus may experience warmth on just one side and suggest how to turn down the heat.

What Does One-Sided Heat Feel Like?

One MyLupusTeam member asked, “Has anyone experienced heat on just one side of the body? The left side of my body feels so much hotter than my right side.” Another agreed, adding, “My lupus tends to swell my left arm and leg more than my right.”

Lupus symptoms can affect the entire body, but they’re not always symmetrical. Some MyLupusTeam members mention feeling warmer on one side — that the right side of their body is hotter than the left or vice versa. Others notice a body temperature difference in just one arm or leg, sometimes as a sudden warm sensation, or between the two sides of their face.

Lupus-Related Causes of One-Sided Heat

Feeling heat on one side of your body could be related to your lupus, your treatment, or an unrelated condition. Lupus causes a variety of symptoms, and some could increase the likelihood of one-sided heat.

Sun Sensitivity

People with lupus often experience photosensitivity and heat intolerance. Exposure to sunlight can lead to various types of rashes (some may resolve within hours, whereas others may persist and need treatment), fever, and joint pain, which might affect one side of your body more than the other.

Sitting in the sun or driving can leave one side of your body more exposed and make that side hotter. Wearing sunscreen or protective clothing on all exposed skin is a good way to prevent this.

Circulation Problems

People with lupus have a higher risk of developing blood clots or blood vessel issues. Blood clots usually occur in one leg at a time and could cause sudden warmth in the leg, along with more prominent symptoms such as pain, tenderness, swelling, and discoloration. These symptoms require immediate medical attention — blood clots are a dangerous condition that may require emergency treatment.

Rashes

Rashes, a common symptom of SLE and cutaneous lupus (a type that affects the skin), are most likely to occur on skin that’s been exposed to the sun, such as chest, upper back, and face. The thick, discolored, scaly rashes and sores can be symmetrical but usually show up on one limb at a time. A rash may feel itchy and produce a burning sensation that could be described as hot.

Muscle and Joint Pain

Lupus often causes musculoskeletal issues such as joint pain and stiffness, which can affect different joints at different times. The symptoms may seem to "migrate" around the body, perhaps affecting one side more than the other. One MyLupusTeam member shared, “I have experienced the one-side-hot feeling. My doc says it happens when your muscles or joints are inflamed.”

Inflammation can occur during a flare (when disease activity is high) and should be managed with proper treatment. Other factors can also trigger inflammation. For instance, after physical activities like yard work or exercise, the immune response may cause inflammation, swelling, and heat in a specific area of the body.

Treatment-Related Causes of One-Sided Heat

Some MyLupusTeam members wonder if side effects of lupus treatment include one-sided heat. While this isn’t a common side effect of most lupus medications, certain treatments could lead to localized reactions. For example, muscle pain and weakness can result from long-term use of glucocorticosteroids.

One member shared, “I experienced one-sided heat this summer. Half of my face felt like it was burning up. When I mentioned it to one of my doctors, he said it might have come from whatever meds I was on at the time.”

Injection Site Reactions

Many treatments for SLE, especially injectables like biologics, can cause localized heat at the injection site. This warmth, along with swelling and soreness, typically happens on the side of the body where the medication was given. For example, if you receive an injection in your left arm, the left side of your body may feel hotter than your right in that area for a short time.

Some people with lupus take antihypertensive drugs (used to treat high blood pressure) for related heart problems. One-sided heat is not a common side effect of these medications or of nonsteroidal anti-inflammatory drugs (NSAIDs) or steroids, often used to manage lupus symptoms.

Drug Allergies

A rare type of drug allergy called a hypersensitivity reaction can cause a rash, itching, fever, and swelling. These symptoms usually affect both sides of the body within 24 hours of receiving a new drug and signal an emergency situation. If you recently began a new IV infusion or injectable biologic, such as rituximab (Rituxan), belimumab (Benlysta), or anifrolumab-fnia (Saphnelo), speak to your doctor about any side effects you are experiencing, whether they affect both sides or just one.

Other Causes of One-Sided Heat

There’s always the possibility that one-sided heat is unrelated to lupus. Other conditions can cause similar sensations, and it’s important to consider these possibilities.

Infection

Infections can cause fevers, making you feel warm. Having a fever, swelling, abnormal skin markings, chills, or flu-like symptoms along with the sensation of one-sided heat could indicate an infection. Check in with your doctor to get medical advice and proper testing, if necessary.

Stroke

One-sided symptoms can sometimes signal an emergency. For example, a stroke can cause sudden, one-sided symptoms, including numbness or warmth. Other symptoms of stroke include vision problems, weakness, dizziness, and lack of coordination. If you believe you may be having a stroke, call your doctor immediately.

Heart Attack

A heart attack, also known as a myocardial infarction, may cause left-sided discomfort, burning, squeezing, pain, or pressure in the chest, arm, jaw, and back. According to the Centers for Disease Control and Prevention (CDC), heart attack symptoms often show up differently in women, who are likely to have other, nonspecific symptoms. If you have a history of cardiovascular disease or high blood pressure and are experiencing these symptoms, seek emergency services.

Managing the Sensation of One-Sided Heat

You can take steps to manage one-sided warmth and find some relief. These tips may help cool you down and reduce discomfort:

• Stay hydrated — Drinking plenty of fluids can help regulate your body temperature. Dehydration can lead to overheating, so stay well hydrated, especially during a lupus flare.
• Wear light, loose clothing — Breathable fabrics help keep your skin cool and reduce sweating and discomfort if one side of your body is overheating.
• Use cold compresses — Applying a cold compress or cool water to the warmer side of your body can bring down the temperature and provide quick relief. You might also consider taking a cool shower.
• Avoid overexertion and overheating — Take a rest and cool down if you notice a sudden warm feeling in your leg or arm during physical activity. Fans or air conditioning can keep your home at a comfortable temperature.

When To See a Doctor

If you’re experiencing persistent, repeating, or worsening one-sided heat as a potential lupus symptom, it’s important to talk with your doctor right away. Your health care team can help determine the underlying cause and suggest the best ways to treat, manage, and reduce this and other symptoms. If you believe this sensation is the side effect of a drug, tell your doctor so that they can determine if your treatment plan is safe and effective for you.

Talk With Others Who Understand

MyLupusTeam is the social network for people with lupus and their loved ones. On MyLupusTeam, more than 231,000 members come together to ask questions, give advice, and share their stories with others who understand life with lupus.

Have you experienced heat on one side of your body while living with lupus? What worked best to help manage this symptom? Share your experience in the comments below, or start a conversation by posting on your Activities page.