HIV is a virus that affects the immune system. Soon after exposure to the virus, a person may experience a rash, a sore throat, a fever, and other flu-like symptoms. As HIV progresses, it can affect various parts of the body.

An estimated 1.2 million people in the United States are living with HIV. However, in the U.S., the number of people getting a new diagnosis of HIV each year has reduced by more than two-thirds since the mid-1980s.

Without treatment, HIV can damage the immune system and increase the risk and effects of other infections. As a result, the virus can affect every part of the body, including the skin, respiratory system, and nervous system.

However, modern treatments are highly effective, and people with HIV can live long and healthy lives.

In this article, we look at how HIV can affect the body, including the early symptoms, effects on the immune system, and late stage opportunistic infections. We also look at how HIV medications can affect the body.

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HIV is a viral infection. It targets and gradually weakens the body’s immune system by damaging cells called CD4 T cells. This damage means that, over time, the body becomes less able to fight off other infections.

If the immune system becomes impaired enough, infections that are typically mild can be life threatening. These are known as opportunistic infections.

When a person contracts HIV, if they do not receive treatment, the infection will typically progress through three stages:

  • Acute infection: Soon after contracting the virus, the person has a large amount of HIV in their blood, and the risk of the virus transmitting to others is high. Some people may experience flu-like symptoms, but others will have no symptoms.
  • Chronic infection: Without treatment, this stage can last for a decade or longer. People may not have any symptoms, but the virus can still transmit to other people.
  • Stage 3 infection (also known as AIDS): At this stage, a person’s immune system is badly damaged, and their CD4 cell count drops below 200 cells per cubic millimeter (cells/mm3) of blood. They will become vulnerable to opportunistic infections, and the risk of viral transmission can be high.

However, HIV treatment, also known as antiretroviral therapy, is effective in slowing or preventing this progression. Antiretroviral therapy has been a treatment option since 1996.

The availability of effective treatment has meant that many people with HIV can have a typical life expectancy and never develop stage 3 HIV. The incidence of opportunistic infections is much lower than before.

When a person first comes into contact with HIV, they may develop flu-like symptoms. These symptoms usually appear within 2–4 weeks of exposure and may last for several days or weeks. Doctors refer to this as seroconversion illness.

Seroconversion is the stage when a person’s body is producing antibodies against HIV, which means that their immune system is fighting the infection.

Many people do not experience any symptoms at this stage, making it easy to have HIV without knowing it. In fact, an estimated 1 in 7 people do not know that they have HIV, which makes testing very important.

If symptoms do occur, the person may feel as though they have the flu. Symptoms of acute HIV infection can include:

After the seroconversion period, the person may not experience any symptoms for a decade or longer. This stage is known as chronic HIV infection.

Although people tend to feel well during this stage, the infection is still active. The virus continues to reproduce, attack new cells, and damage the immune system. It is also possible that the virus will spread to others.

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HIV primarily affects the body by targeting and damaging cells in the immune system. The immune system protects the body against viruses, bacteria, and fungi.

After attaching itself to a type of white blood cell called a CD4 T cell, the virus merges with it. These T cells are an important part of the immune system.

Once inside the CD4 T cell, the virus multiplies. It damages or destroys the cell, then moves on and targets other cells.

A person’s CD4 T-cell count is an indication of the health of their immune system.

A healthy CD4 T-cell count is 500–1,600 cells/mm3 of blood. If a person does not receive treatment for HIV, their CD4 T-cell count drops over time.

When it drops below 200 cells/mm3, the person’s immune system is significantly impaired, making them more susceptible to opportunistic infections.

Opportunistic infections

Opportunistic infections are viral, bacterial, or fungal infections that take advantage of a weakened immune system.

These infections are typically mild in people without HIV but can be severe or life threatening in people with a low CD4 T-cell count, such as those with stage 3 HIV.

A person may receive a diagnosis of stage 3 HIV if they develop an opportunistic infection.

Some of the most common opportunistic infections in the U.S. are:

The treatment for an opportunistic infection will depend on the type of infection, but options include antiviral drugs, antibiotics, and antifungal medications.

Other opportunistic infections include:

Many people with HIV develop coinfections, which means that they have two or more infections at the same time.

Hepatitis B and hepatitis C are common coinfections. People can contract these viruses in similar ways as HIV, such as through sexual contact and sharing equipment to inject drugs.

Tuberculosis, which is a respiratory condition that a bacterium called Mycobacterium tuberculosis causes, is another common coinfection. A person may have latent tuberculosis, which means that these bacteria live in their body, but they do not get sick.

The risk of developing tuberculosis after exposure to the bacteria is higher for people with HIV who are not receiving treatment for it.

The Centers for Disease Control and Prevention (CDC) recommend that everyone with HIV undergo testing for hepatitis B, hepatitis C, and tuberculosis, even if they have no current signs or symptoms.

Receiving a diagnosis of HIV and living with the condition can have significant effects on a person’s mental health.

According to the National Institute of Mental Health, people living with HIV are twice as likely to have depression than those without HIV. They are also at a higher risk for mood, anxiety, and cognitive disorders.

There are specific sources of stress relating to the condition, such as having to find and manage medical support, managing the lifelong use of medications, and dealing with the stigma and discrimination associated with HIV.

Some antiretroviral drugs may also cause mental health side effects, such as anxiety.

Many mental health problems are treatable. Talking therapies, medications, and social support can all help.

The CDC provide a list of services that can help people manage the stigma and discrimination linked with HIV and receive additional support.

For more information about where to find support when living with HIV, people can visit the website.

While there is no cure for HIV, antiretroviral therapy can reduce the amount of the virus in the blood to very low levels. By doing this, it keeps the person healthy and prevents the transmission of the virus to other people.

A very low, or undetectable, viral load means that the risk of transmission to others is virtually zero, which has led to the phrase: undetectable = untransmittable (U=U).

Experts encourage all people with HIV, regardless of their CD4 T-cell count, to start taking antiretroviral drugs as soon as possible after their diagnosis. Early treatment is key to a good outcome.

As with other medications, antiretroviral drugs can cause side effects in some people. However, modern drugs tend to produce fewer and less severe side effects than older drugs.

Possible side effects of antiretroviral drugs include:

  • fatigue
  • headaches
  • diarrhea
  • nausea or vomiting
  • difficulty sleeping
  • dry mouth
  • a skin rash
  • dizziness
  • pain

Some side effects may last for a few days or weeks after the person starts treatment. Others may start later or last longer.

If a person experiences severe side effects that make them consider stopping treatment, they can talk to their healthcare provider. Stopping treatment or skipping doses can lead to drug resistance and limit a person’s treatment options.

Some people can reduce some side effects by taking the medication 2 hours before going to bed. Other people may prefer to take it in the morning to prevent sleep disturbances.

When taking antiretroviral drugs, a person needs to be aware that their medication may interact with other prescription medications, as well as herbal remedies and recreational drugs.

Certain HIV drugs may also lead to less obvious changes, such as:

  • increased cholesterol and other fats in the blood
  • liver or kidney problems
  • changes in the distribution of body fat, in people taking older HIV drugs

Healthcare providers can monitor for these issues during routine checkups.

Despite these problems, there is now evidence of the long-term safety of antiretroviral therapy, which can significantly increase life expectancy for many people with HIV.

Read more about treatments for HIV here.

HIV is a virus that affects the immune system. Without treatment, it can damage the immune system, increasing the risk of other infections and leading to possible complications across the body.

However, antiretroviral therapy lowers the amount of HIV in the body, which prevents it from damaging the immune system. This treatment has led to opportunistic infections becoming much less common.

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