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Human immunodeficiency virus (HIV)

Human immunodeficiency virus (HIV) is a virus that weakens your body’s immune system by destroying CD4 (T-cell) lymphocytes.

Last updated 20 May 2025

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What is human immunodeficiency virus (HIV)?
What is acquired immunodeficiency syndrome (AIDS)?
How is HIV transmitted?
What are the symptoms of HIV?
What are the risk factors?
How to test for HIV? 
Understanding HIV test results
What to do when diagnosed with HIV?
Do I need to tell my sexual partner that I have HIV?
How to prevent HIV?
What is pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP)treatment?
How to treat HIV?
Educational materials
About the National HIV Programme

What is human immunodeficiency virus (HIV)?

HIV is a virus that weakens your body’s immune system by destroying CD4 (T-cell) lymphocytes. This makes it harder for the body to fight infections, and increases the severity of common conditions and diseases, including cancer.

HIV is spread through bodily fluids like breast milk, blood, semen, or vaginal discharge from a person living with HIV. 

If untreated, HIV can lead to acquired immunodeficiency syndrome (AIDS). 

What is acquired immunodeficiency syndrome (AIDS)?

AIDS is an advanced stage of HIV infection, causing your immune system to be severely weakened. You receive an AIDS diagnosis when:

  • Your CD4 cell count falls below 200 cells/mm3; or

  • You develop one or more opportunistic infections regardless of your CD4 cell count.

For reference, a healthy CD4 cell count is above 500 cells/mm3.

How is HIV transmitted?

HIV is most commonly transmitted through the act of unprotected sex with a person with HIV, but it can also be transmitted by:

  • Sharing injection needles or piercing instruments (e.g. tattoo guns or acupuncture needles) with a person with HIV.

  • Receiving infected blood or blood products (e.g. blood transfusion, organ transplant).

  • An HIV-infected mother during pregnancy, childbirth, or breastfeeding.

HIV does not spread via:

  • Shaking hands, hugging, or touching

  • Saliva, tears, or sweat

  • Kissing

  • Coughing or sneezing

  • Sharing food and drinks

  • Toilet seats

  • Touching of common surfaces

  • Mosquitoes, ticks, or other insects

  • Air or water

  • Drinking fountains

What are the symptoms of HIV?

Symptoms of HIV vary from person to person and may differ depending on the stage of infection. Early symptoms may include:

  • Tiredness

  • Weight loss

  • Prolonged fever

  • Skin rash

  • Night sweats

  • Persistent diarrhoea

  • Lowered resistance to infections

You cannot tell if someone has HIV just by their symptoms. The only way to know for sure is to take an HIV test.

HIV can take up to 10 years to progress to AIDS without medical intervention.

What are the risk factors?

Risk factors include:

  • Unprotected sex

  • Use of non-sterile needles or instruments such as people with a history of injection drug use, body piercing, or tattoos

How to test for HIV? 

Getting tested for HIV is the only way to know your status. Delaying detection and diagnosis could lead to poorer prognosis and treatment outcomes, increasing the risk of transmission.

The Communicable Diseases Agency (CDA) recommends people aged 21 years old and above or those who are sexually active should undergo HIV testing at least once in their lifetime. For individuals who engage in at risk behaviours, such as having multiple sexual partners or casual sex, it is encouraged to go for HIV testing more frequently, or every 3 to 6 months.

You can get yourself tested for STIs or HIV/AIDS at most GP (General Practitioner) clinics, polyclinics, Department of Sexually Transmitted Infections Control (DSC) clinic, and hospitals in Singapore. Some sites provide anonymous or rapid testing services, where the latter can provide results in 20 minutes. Find out where to test for HIV here.

You can also use HIV self-test kits. They can be purchased at selected retail pharmacies nationwide and Action for AIDS (AfA)*. Learn about HIV self-testing here.

*Designated supply sites for HIV self-testing kits are limited to licensed retail pharmacies nationwide (in-store and online) and at the AfA.

Understanding HIV test results

You tested negative for HIV. What’s next?

A negative result means there were no signs of a HIV infection in your sample. However, you might still be infected because HIV takes about one to six weeks to incubate. The time between potential exposure and testing is called the window period.

Different HIV tests have different window periods. Ask your healthcare provider about the window period for the HIV test you are taking. For HIV self-test kits, you can find the information in the package. 

If you have a negative HIV test result and the last possible HIV exposure was:

Less than 72 hours ago

You may need post-exposure prophylaxis (PEP).

Less than 90 days ago

You will need to repeat the HIV test.

If you get a negative test result again after the window period, and have no possible HIV exposure during that time, then you do not have HIV. 

You tested HIV positive, What’s next?

All positive test results require a follow-up test for confirmation. 

If you test positive:

On a HIV self-test kit

Repeat the testing at a healthcare facility; includes anonymous testing sites.

At a healthcare facility

Repeat testing will be done automatically.

If you get a positive test result again, it means you have HIV. 

What to do when diagnosed with HIV?

There is currently no effective cure for HIV, but it can be controlled with proper care. This can be done through antiretroviral therapy (ART). With effective treatment, the HIV virus can be suppressed to undetectable levels, allowing people living with HIV to lead a long, healthy lives and protect their partners.

HIV treatment is available in most public hospitals and private healthcare institutions in Singapore.

Most HIV medications are subsidised, making them accessible and affordable.

Do I need to tell my sexual partner that I have HIV?

Under the Infectious Diseases Act, you must inform your sexual partner of the risks of getting HIV from you before having sex, unless you have maintained a stable undetectable HIV viral load (see below criteria). This is to allow your partner to make a choice to take appropriate precautions.

You are considered to have maintained a stable undetectable HIV viral load if you satisfy the following criteria:

  1. Stable, consecutive undetectable HIV viral load test results (below 200 copies per millilitre of blood), for at least 6 months;

  2. Most recent HIV viral load test shows a result of undetectable (below 200 copies per millilitre of blood), and is dated 9 months or less before you have sex;

  3. All the HIV viral load test results mentioned above are from a licenced laboratory in Singapore; and

  4. Adhered to medical treatment for HIV infection up to the time of when you have sex.

If the above criteria are satisfied, you do not pose a risk of transmitting of HIV to your sexual partner. Therefore, you do not need to inform your sexual partner of the risks of getting HIV from you.

How do I show that I have adhered to medical treatment for HIV infection?

You should go for regular follow-up visits for HIV with your doctor, including regular HIV viral load testing, and prescription refills. Documented medical records serve as evidence that you have adhered to medical treatment.

If you are alleged to have committed an offence, the strongest evidence that you have adhered to medical treatment is an undetectable HIV viral load test result (from a licenced laboratory in Singapore) at the next medical visit for HIV after the sexual activity in question (which should not be more than 9 months after the sexual activity in question). This is because maintenance of undetectable HIV viral load is not possible unless you have adhered to treatment.

How to prevent HIV?

You can protect yourself from HIV by:

  • Practising the ABCD approach to prevent HIV (Abstinence from casual sex, Be faithful, Correct and consistent condom usage, and early Detection).

  • Visiting a reliable service provider who uses clean, sterile needles for any tattoos, piercings or injections.

What is pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP)treatment?

In Singapore, Pre-exposure prophylaxis (PrEP) and Post-exposure prophylaxis (PEP) are supplementary HIV preventive options. Those who wish to use PrEP/PEP can visit their doctor to be assessed for their suitability to be prescribed the drugs.

What is Pre-exposure prophylaxis (PrEP) treatment?

PrEP involves the use of HIV medication for people who do not have HIV but are at risk of HIV infection. When taken as prescribed, PrEP can protect against HIV, but condom use is still important to prevent other sexually transmitted infections (STIs).

What is post-exposure prophylaxis (PEP) treatment?

PEP is a short course of HIV medication to prevent its transmission. It must be used within 72 hours of possible high-risk exposure and should only be used during emergencies. High-risk exposure to HIV includes:

  • Any unprotected sex with someone who is HIV positive

  • Sharing or exposure to contaminated needles or blades, particularly needle-stick injuries

  • Victims of sexual assault

Should you require PEP during emergencies, please visit the Emergency Department of any public hospital and request for it.

How to treat HIV?

Antiretroviral Therapy (ART) is recommended for all individuals living with HIV. Although ART cannot cure HIV, it can control the virus and help them live longer, healthier lives. ART can also reduce the risk of HIV transmission, but it does not prevent transmission of other STIs.

People living with HIV who take the medicine as prescribed can suppress their HIV viral load to an undetectable level (less than 50 copies/ml), reducing the risk of HIV transmission to others (i.e. Undetectable = Untransmittable, U=U).

Educational materials

National HIV recommendations and guidelines 

Developed by the National HIV Programme (NHIVP), the following recommendations and guidelines are used to promote HIV prevention, treatment, and care:

  • HIV Testing Recommendations

  • Pre-Exposure Prophylaxis (PrEP) Guidance

  • Antiretroviral Therapy (ART) Recommendations 

  • Primary Care Recommendations

Find the guidelines here.

To read more about HIV, click here.

HIV Doesn’t Differentiate (2022 to 2024)

Content Pieces

With Early and Effective Treatment, People Living with HIV Can Lead Lives No Different from Others (2021) 

Content Pieces

It’s Time to Spread the Facts (2019)

Articles in media and publications

About the National HIV Programme

Get more information on the programme here.