Because HIV weakens the immune system, it makes an infected person very susceptible to various opportunistic disease, cancers, and viruses that take advantage of weakened immunity.

Antiretroviral drugs used to treat HIV can also cause serious medical complications, such as abnormal fat distribution, abnormal lipid and glucose metabolism, and bone loss.

Common Opportunistic Infections

Tuberculosis

Tuberculosis (TB) is the most common opportunistic infection associated with HIV. For people with healthy immune systems, tuberculosis does not cause as great a danger as those suffering from a weakened immune system. TB affects the lungs or central nervous system and travels through the air, making it very easy to contract. 
Learn more about tuberculosis.

Salmonellosis

Salmonellosis (also known as salmonella food poisoning) is a bacterial infection contracted through contaminated food or water, causing diarrhea, fever, abdominal pain, vomiting, and chills.
Learn more about salmonella.

Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a herpes virus transmitted through saliva, blood, urine, semen, and breast milk. In a healthy person, CMV can remain dormant, but in a person with a weakened immune system, CMV can cause damage to the eyes, digestive tract, lungs, or other organs. It is a highly feared HIV-associated infection because it can cause blindness.
Learn more about CMV infection.

Candidiasis

Also known as “thrush,” this infection can affect the mouth and throat or vagina, causing inflammation and a thick white coating on mucous membranes. This infection can also get into the bloodstream and be very dangerous to people with HIV.
Learn more about thrush.

Toxoplasmosis

This parasitic infection is often spread through cats or contaminated water or meat. A person with a healthy immune system can keep the parasite from causing illness. However, in the case of a compromised immune system, toxoplasmosis can cause brain defects, blindness, and damage to the central nervous system.
Learn more about toxoplasmosis.

Opportunistic Cancers

HIV weakens the immune system, making a patient vulnerable to certain cancers.  It is important to detect early signs of cancers, before they progress too far to be treated and produce untreatable negative effects on the body.  The most common AIDS-related cancers include:

Kaposi’s Sarcoma

Kaposi’s sarcoma is most commonly associated with people infected by HIV. It is a tumor of the blood vessel walls, which usually manifests as pink, red, or purple lesions on the skin and mouth. These tumors may also infect a person internally on the digestive tract or lungs. It is believed to be caused by a virus known as HHV-8.
Learn more about Kaposi's sarcoma.

Lymphoma

This cancer, originating in the white blood cells, usually begins in the lymph nodes, causing swelling in an infected neck, armpit, or groin. 
Learn more about lymphoma.

Other Complications

Wasting Syndrome

Wasting syndrome is marked by unintended weight loss (of at least 10 percent) and accompanied by diarrhea, chronic weakness, and fever.

Neurological Complications

HIV can cause indirect damage to the nerve cells, causing confusion, forgetfulness, depression, anxiety, and trouble walking. Many HIV sufferers develop dementia, which can inhibit mental function.