How does CD4 count relate to the risk of becoming ill?

Your CD4 count is closely related to your risk of becoming ill. Your CD4 count and how it changes over time is used to decide when to start treatment.

Above 500, the risk of HIV-related problems is very low. The START study showed that there are still benefits to being on ART with a high CD4 count. ART reduced the risk of serious complications.

Above 350, you still have a very good immune system but still are at higher risk of TB. As it drops below 350, the risk of skin or digestion problems increase.

Below 200 there is an added risk of a pneumonia called PCP.

Below 100 you become vulnerable to other very serious illnesses.

Below 50 the risks are higher still, including from a virus called CMV that can cause permanent sight loss. A CD4 count this low requires special eye checks.

HIV meds are much easier to take than drugs used to treat these HIV-related problems.

Although you may be worried about treatment, HIV is still a very real and life-threatening illness.

Deciding when to start treatment is discussed in more detail later in this guide.

Last updated: 1 October 2019.