Active HIV Infection
When your HIV infection is active, your body uses its stored energy to fight the invading infectious organisms, or pathogens. Fatigue will set in unless this energy is replenished.¹

Other Diseases or Infections
Opportunistic infections, fungal diseases and parasitic diseases are common in people with HIV/AIDS, and many, such as Pneumocystis (carinii) jiroveci pneumonia, can cause fatigue.

Anemia
Anemia occurs when you don't have enough red blood cells or if they aren't carrying enough oxygen to your tissues and vital organs, leading to fatigue. In people with HIV/AIDS, there are many causes of anemia, including opportunistic infections, the medications used to treat HIV/AIDS, and a lack of essential nutrients, such as iron, vitamin B12 and folic acid.²

Hormonal Imbalances
Low levels of hormones, such as testosterone, thyroid hormone and cortisol, can cause fatigue. People with HIV/AIDS may experience hormonal imbalances due to the virus itself or due to opportunistic infections and the drugs used to treat them.³

Medications
Drug side effects are a major cause of fatigue in people with HIV/AIDS. In some cases, fatigue is a side effect of the medications used to treat HIV/AIDS. In other cases, the medications cause anemia or disrupt sleep patterns, leading to fatigue.

Psychological Factors
At some point, many people with HIV/AIDS suffer from depression, symptoms of which include decreased energy, lack of stamina or a feeling of tiredness or fatigue all the time.⁴ Anxiety, common among people with HIV/AIDS, is also associated with fatigue.⁵

Insomnia/Poor Sleep
Many people with HIV/AIDS have problems sleeping, which can lead to fatigue. Common reasons for insomnia or disrupted sleep include psychological factors (such as depression, anxiety and stress), physical conditions (such as diarrhea or pain), and certain medications and recreational or illegal drugs.⁶

Substance Use/Abuse
Caffeine and alcohol can interfere with sleep and cause fatigue, as can the use of recreational or illegal drugs.

Malnutrition
People with HIV/AIDS may not be able to maintain an adequate and healthful diet, putting them at risk of malnutrition and fatigue. The disease itself, symptoms caused by opportunistic infections and medication side effects can cause loss of appetite, nausea, changes in taste, and sores in the mouth or throat, making it difficult for those with HIV/AIDS to consume enough calories and nutrients.⁷

Lack of Physical Exercise
Unlike physical inactivity, which can actually cause fatigue, light to moderate exercise has been shown to increase energy. Physical activity also helps to increase muscle mass, reduce stress, regulate sleep patterns and increase the appetite, all of which are beneficial to those with HIV/AIDS.⁸