The symptoms of a weak immune system are directly related to its inability to effectively protect the body from disease-causing organisms. When functioning correctly, the immune system defends against bacteria, viruses, fungi, malignant cells and other harmful substances. The first line of defense includes barriers, such as the skin and mucous membranes. If invading pathogens pass through these barriers, they face a generalized immune response followed by a specific response from the lymphocytes. When any facet of the immune system is weakened, the result may be increased frequency and duration of infections.
If pathogens are not effectively eliminated by the body’s natural defenses, the symptoms of a weak immune system manifest as increased susceptibility to disease. People with an impaired immune system may have more frequent colds, flu or fungal infections. The severity of the illnesses may be worse and last longer than average. Infections that recur — such as frequent kidney, sinus or ear infections — may also indicate a compromised immune system. Other symptoms might be slow-healing or frequently-infected wounds.
Illnesses are sometimes more difficult to treat when people have a weakened immune system. A regular course of antibiotics might not kill an infection in someone with a compromised immune system. Intravenous antibiotics may be required to effectively eliminate tenacious infections. Many signs of illness are actually due to the immune system fighting the infection. The aches, pains and fever associated with some illnesses are signs that the immune system is working.
An immune system disorder may also play a role in the development of some long-term diseases. There is evidence that an impaired immune system is linked to chronic fatigue syndrome and chronic inflammation. It may also show up as long-term digestive disorders. Persistent vomiting, diarrhea or loss of appetite may signal an underlying immune deficiency. Certain types of anemia and other blood disorders may also be symptoms of a weak immune system.
Autoimmune disorders are a dysfunction of the immune system that prevent it from recognizing parts of the self. Rather than targeting only pathogens, the immune system mistakenly attacks the body’s own cells. People suffering from lupus, rheumatoid arthritis and other autoimmune disorders may also exhibit the symptoms of a weak immune system. They may experience more frequent infections than the general population.
It is normal for young children and the elderly to have weaker immune systems than people of other ages. Alcoholism, drug use and smoking can also lower the functioning of the immune system. In addition, the lack of adequate nutrition is a frequent cause of immune deficiencies in developing countries. An illness may also temporarily weaken the immune system. Nutrient dense foods, exercise and sufficient sleep are recommended for maintaining a healthy immune system.