10 Most Common Symptoms of Legionnaires’ Disease

2. High Fever

A high fever is one of the most common signs of Legionnaires’ disease. Your body temperature can rise quickly, often reaching 102°F (39°C) or higher. This is your immune system reacting to the bacterial infection in your lungs. You may notice that the fever starts within 2 to 14 days of exposure. It often appears along with chills and heavy sweating.

The fever can make you feel weak and drained. A high fever can make it hard for you to think clearly. Some people feel confused or disoriented, especially older adults. When your temperature stays high, your heart may beat faster and your breathing may speed up.

Fever also increases your risk of dehydration. You may lose fluids through sweat and breathe faster than normal. If you already have a chronic illness or a weakened immune system, a high fever can put extra stress on your body.

3. Chills

Chills often start early in Legionnaires’ disease. You may feel sudden waves of cold, even when the room feels warm. Your body may shake or tremble as it tries to raise your temperature, and chills usually happen along with a high fever. As your body fights the infection in your lungs, it raises its internal temperature.

This rapid change can make you feel cold and shaky at the same time. You might notice that chills come in episodes. They can last several minutes and may repeat throughout the day. During these periods, your teeth may chatter, and you may need extra blankets even though your skin feels hot.

Chills can also make you feel weak and tired. The shaking uses energy, and the fever adds stress to your body. You may find it hard to rest comfortably. Pay attention to how severe the chills feel. Strong chills with a high fever and cough can point to a serious lung infection.

4. Headaches

Headaches are a common symptom of Legionnaires’ disease. You may notice a steady, dull pain that starts early in the illness. For some people, the pain becomes strong and hard to ignore. This headache often appears along with fever and muscle aches.

When your body fights the infection, it releases chemicals that can trigger head pain. The fever itself can also make your head feel heavy or tight. You might feel pain across your forehead or at the back of your head. Some people describe it as pressure, while others feel throbbing.

Bright light and noise can make it worse. Headaches linked to Legionnaires’ disease usually do not happen alone. You may also have a cough, shortness of breath, chest pain, nausea, or confusion. When these symptoms show up together, they point to a lung infection rather than a simple cold. Drinking fluids and resting may ease mild discomfort.

5. Soreness

You may feel soreness in your muscles early in Legionnaires’ disease. This muscle pain often starts suddenly and can affect your legs, back, or arms. It may feel like the body aches you get with the flu. The soreness can make simple tasks harder, and you might feel stiff when you get out of bed or tired after light activity.

Some people also report joint discomfort along with muscle pain. Chest soreness can happen if you develop pneumonia. When you cough often, the muscles in your chest and ribs can become tender. Deep breathing may also feel uncomfortable. This soreness usually comes with other symptoms such as fever, cough, headache, or fatigue.

You may also notice general body weakness. Your muscles can feel heavy, and you may not have your usual strength. Rest may not fully relieve the discomfort. If the infection becomes severe, you might need care in a hospital. Healthcare providers may use antibiotics to treat the bacterial infection and support your breathing while your body recovers.

6. Chest Pain

You may feel chest pain when Legionnaires’ disease affects your lungs. This infection causes a type of pneumonia, which can irritate the lining around your lungs. When you breathe in or cough, the pain can become sharper. Chest pain often feels worse with deep breaths. Some people describe it as a stabbing or tight feeling in one area of the chest.

Others feel a dull ache that stays constant. You may also notice other symptoms at the same time, such as a cough that is dry at first, fever and chills, shortness of breath, and fatigue. If your lungs fill with fluid or become inflamed, your chest may feel heavy.

You might avoid taking deep breaths because it hurts. This can make you feel more short of breath. Chest pain from Legionnaires’ disease does not always mean a heart problem. However, it can still feel strong and uncomfortable, and chest pain along with fever and cough needs medical care.

7. Fatigue

Fatigue is a common symptom of Legionnaires’ disease. You may feel very tired even after you rest. Simple tasks, like walking across a room or taking a shower, can feel harder than usual. This type of fatigue is more than normal tiredness. Your body works hard to fight the lung infection, and that effort drains your energy.

You may feel weak, slow, or unable to focus on daily activities. Fatigue often appears along with fever, cough, and shortness of breath. When your body temperature rises, your energy levels can drop. If you also have nausea or diarrhea, fluid loss can make you feel even more worn out.

You might notice that your muscles feel heavy or sore. You may want to sleep more than usual but still wake up feeling unrefreshed. This ongoing tired feeling can last for days or even weeks, especially if the infection is severe.

8. Nausea and Vomiting

You may feel nausea or start vomiting when you have Legionnaires’ disease. These symptoms can appear along with fever, cough, and muscle aches. They often begin in the first few days of illness, and nausea is the feeling that you might throw up.

Vomiting is when your body forces the contents of your stomach out through your mouth. Some people also notice stomach pain or diarrhea at the same time. This infection mainly affects your lungs, but it can also upset your digestive system.

The bacteria can trigger inflammation in your body, and that response may affect how your stomach and intestines work. Vomiting can lead to dehydration if it happens often. You may lose fluids and minerals your body needs to function well. Signs of dehydration include dry mouth, dark urine, and feeling dizzy when you stand up.

9. Shortness of Breath

Shortness of breath is a common symptom of Legionnaires’ disease. You may feel like you cannot get enough air, even when you are resting. Simple tasks such as walking across a room can leave you winded. This symptom happens because the infection causes pneumonia, which can fill the lungs with fluid and lead to inflammation.

When this occurs, oxygen has a harder time moving into your blood. Shortness of breath often appears along with a cough and fever. It can start within 2 to 14 days after you breathe in contaminated water droplets. In some cases, it becomes worse over several days.

If your breathing feels harder than usual, your body is working harder to move oxygen. You may also feel tired, anxious, or lightheaded. Severe breathing problems can signal that the infection is serious and may require hospital care.

10. Confusion or Altered Mental State

Legionnaires’ disease can cause confusion or changes in thinking, often appearing along with fever and cough. These mental changes may start a few days after you begin to feel sick. Older adults and people with existing health problems or weak immune systems face a higher risk. Confusion can feel different for each person, but you might have trouble focusing, forget simple things, or struggle to follow a conversation.

Some people seem disoriented and do not know where they are or what day it is. This symptom often links to high fever and low oxygen levels caused by pneumonia. When your lungs cannot move enough oxygen into your blood, your brain may not work as well. Severe infection can also affect how your body controls fluids and chemicals, which can change your mental state.