Types of HIV Medication: PrEP, PEP and HIV Treatment Explained

When people search for the types of HIV medication, they may be looking for medicines used to prevent HIV, medicines taken after a potential exposure, or treatment for someone who already has HIV.

These are not the same thing.

In general, HIV medication can be divided according to its purpose:

• PrEP (pre-exposure prophylaxis) is used to reduce the risk of acquiring HIV before potential exposure.
• PEP (post-exposure prophylaxis) is a short course of HIV medication used after a potential exposure.
• Antiretroviral therapy (ART) is used to treat HIV in people living with the virus.

Singapore’s Communicable Diseases Agency (CDA) recognises PrEP and PEP as HIV prevention options and recommends ART for people living with HIV.

This guide explains the different types of HIV medication, the main antiretroviral drug classes, and how PrEP, PEP and HIV treatment differ.

What are HIV medications?

HIV medications are medicines that act against human immunodeficiency virus (HIV). They are commonly called antiretroviral drugs (ARVs).

Depending on the medication and how it is used, antiretroviral drugs can help:

• Prevent HIV infection before exposure
• Reduce the risk of HIV infection after a potential exposure
• Control HIV infection in someone living with HIV
• Reduce the amount of HIV in the blood to an undetectable level when treatment is taken consistently

HIV medications work by interfering with different stages of the HIV life cycle. There are several classes of antiretroviral drugs, and treatment regimens may combine medicines from different classes. 

It is important to understand that PrEP, PEP and ART describe how HIV medicines are used, rather than simply referring to three individual drugs.

What are the main types of HIV medication?

The easiest way to understand the different types of HIV medication is to look at what they are being used for. 

PrEP: HIV medication before exposure

PrEP, or pre-exposure prophylaxis, is HIV medication taken by people who do not have HIV to reduce their risk of acquiring HIV.

PrEP can be taken according to different dosing strategies depending on the medication, clinical guidance and the individual’s circumstances.

PEP: HIV medication after exposure

PEP, or post-exposure prophylaxis, is a short course of HIV medication taken after a potential exposure to HIV.

PEP is an emergency prevention measure. In Singapore, it must be started within 72 hours of a possible high-risk exposure, and it should be started as soon as possible.

ART: HIV treatment

ART, or antiretroviral therapy, is used to treat people living with HIV.

ART does not cure HIV, but it can suppress the virus to very low levels, helping protect the immune system and reducing the risk of transmitting HIV when an undetectable viral load is maintained.

1. PrEP medication

PrEP stands for pre-exposure prophylaxis.

It involves taking antiretroviral medication before potential exposure to HIV. When taken as prescribed, PrEP can significantly reduce the risk of acquiring HIV.

In Singapore, PrEP is available as a prescription-based HIV prevention option following medical assessment.

Oral PrEP commonly uses antiretroviral medicines such as tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC). Other formulations may also be appropriate depending on the individual’s circumstances and current clinical recommendations.

Daily PrEP

Daily PrEP involves taking medication regularly, typically once a day.

It may be suitable for people who have frequent or unpredictable potential exposure to HIV and prefer ongoing protection rather than planning doses around sexual activity.

On-demand PrEP

On-demand PrEP, sometimes called 2-1-1 PrEP, involves taking PrEP around planned sexual activity rather than taking it every day.

Whether this dosing strategy is appropriate depends on the individual’s circumstances and the applicable clinical guidance.

Read more: Daily PrEP vs on-demand PrEP

Related guide: Injectable PrEP

Related treatment page: HIV PrEP in Singapore

2. PEP medication

PEP stands for post-exposure prophylaxis.

It is a short course of antiretroviral medication used after a potential exposure to HIV to reduce the risk of infection.

Unlike PrEP, which is taken before potential exposure, PEP is an emergency measure used after a potential exposure.

In Singapore, PEP must be used within 72 hours of a possible high-risk exposure. The sooner it is started, the better.

Potential situations in which PEP may be considered include:

• condomless sex involving a potential HIV exposure
• a condom breaking during sex
• exposure to blood through a needlestick injury
• sharing or exposure to contaminated needles or blades
• sexual assault

Whether PEP is appropriate depends on the type of exposure, the likelihood that HIV was present and other clinical factors. A doctor should assess the situation rather than relying on symptoms or waiting to see whether symptoms develop.

If you think you may need PEP, seek medical attention promptly. Do not wait until the 72-hour window is nearly over.

Read more: How to get HIV PEP in Singapore

Related treatment page: HIV PEP in Singapore

3. HIV treatment medication: antiretroviral therapy (ART)

For people living with HIV, treatment is known as antiretroviral therapy (ART).

ART uses combinations of antiretroviral medicines to suppress HIV replication. Singapore’s CDA recommends ART for all individuals living with HIV.

ART does not remove HIV from the body or cure the infection. Instead, it keeps the amount of virus in the body under control.

When ART is taken consistently and viral suppression is achieved, the viral load can become undetectable. Maintaining an undetectable viral load prevents sexual transmission of HIV, commonly described as U=U (Undetectable = Untransmittable).

The specific combination of medicines used for HIV treatment depends on factors such as:

• the person’s HIV resistance profile
• other medical conditions
• potential drug interactions
• previous HIV treatment
• kidney and liver function
• other medications being taken
• the individual’s clinical circumstances

For this reason, HIV treatment should be selected and monitored by a healthcare professional.

What are the different classes of HIV medication?

HIV medicines are grouped into different antiretroviral drug classes according to how they interfere with the HIV life cycle.

The major classes include:

1. Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
2. Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
3. Integrase strand transfer inhibitors (INSTIs)
4. Protease inhibitors (PIs)
5. Other, less commonly used antiretroviral classes

Singapore’s Agency for Care Effectiveness (ACE) identifies NRTIs, NNRTIs, INSTIs and PIs among the antiretroviral drug classes used in HIV treatment in Singapore.

Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)

NRTIs interfere with an HIV enzyme called reverse transcriptase.

HIV needs this enzyme to convert its genetic material into a form that allows it to replicate inside human cells.

Examples of NRTIs include:

• tenofovir disoproxil fumarate (TDF)
• tenofovir alafenamide (TAF)
• emtricitabine (FTC)
• lamivudine (3TC)
• abacavir
• zidovudine

NRTIs are commonly used in combination with medicines from another antiretroviral class as part of HIV treatment.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

NNRTIs also target reverse transcriptase, but they bind to the enzyme differently from NRTIs.

Examples include:

• efavirenz
• rilpivirine
• etravirine
• nevirapine
• doravirine

NNRTIs may form part of certain HIV treatment regimens depending on the individual’s clinical circumstances.

Integrase strand transfer inhibitors (INSTIs)

INSTIs block an HIV enzyme called integrase.

HIV uses integrase to insert its genetic material into the DNA of infected human cells. Blocking this process prevents the virus from completing an important stage of its replication cycle.

Examples include:

• dolutegravir
• bictegravir
• raltegravir
• cabotegravir

INSTI-based regimens are an important part of modern HIV treatment.

Protease inhibitors (PIs)

Protease inhibitors block an HIV enzyme called protease.

HIV uses protease to produce mature viral particles. Blocking this enzyme interferes with the production of infectious HIV.

Examples include:

• darunavir
• atazanavir
• lopinavir
• ritonavir

Protease inhibitors may be used in particular treatment situations, including when a person’s clinical history or resistance profile makes them appropriate.

Other antiretroviral drug classes

There are also several other classes of HIV medication that target different stages of the HIV life cycle.

These include:

• fusion inhibitors
• CCR5 antagonists
• post-attachment inhibitors
• attachment inhibitors
• capsid inhibitors

These medicines are generally used in specific treatment situations rather than being the mainstay of routine PrEP.

The NIH currently recognises multiple antiretroviral drug classes based on their mechanisms of action against HIV.

What are combination HIV medications?

HIV treatment often uses more than one antiretroviral medicine.

Rather than taking several separate tablets, some medicines are available as fixed-dose combination pills, where two or more active medicines are combined into one tablet.

For example, Singapore ACE materials describe fixed-dose combinations containing two or three antiretroviral medicines.

Combination treatment allows medicines that work in different ways to be used together and can make treatment easier to take.

The specific combination prescribed depends on the person’s HIV infection, resistance profile, other health conditions, potential drug interactions and other clinical factors.

What is the difference between PrEP, PEP and ART?

Although PrEP, PEP and ART all involve antiretroviral medication, they have different purposes. 

The simplest way to remember it

PrEP = before exposure

PEP = after exposure

ART = treatment for HIV

PrEP and PEP are therefore prevention strategies, while ART is HIV treatment.

Is PrEP the same as HIV treatment?

No.

PrEP is intended for people who do not have HIV and want to reduce their risk of acquiring it.

ART is used by people who have HIV to suppress the virus.

Although both involve antiretroviral medicines, the purpose and clinical management are different.

This is also why HIV testing is an important part of PrEP care. Someone with undiagnosed HIV should receive an appropriate HIV treatment regimen rather than taking a prevention regimen alone.

If you are considering PrEP, a doctor can assess whether it is appropriate for you and advise on HIV testing and ongoing monitoring.

Is PEP the same as PrEP?

No.

The easiest way to distinguish them is by when they are used.

PrEP is taken before potential exposure to HIV.

PEP is taken after a potential exposure to HIV.

PEP is an emergency intervention and needs to be started within 72 hours of a possible high-risk exposure. It should be started as soon as possible.

If you think you may have been exposed to HIV recently, seek medical assessment promptly rather than waiting for symptoms.

Which HIV medication is right for me?

There is no single HIV medication that is right for everyone.

The appropriate medicine or regimen depends on why the medication is being used and on individual clinical factors.

A doctor may consider:

• whether you have HIV
• whether you are taking medication for prevention or treatment
• whether a potential exposure has already occurred
• how long ago the potential exposure happened
• your kidney and liver function
• other medicines you take
• possible drug interactions
• previous PrEP, PEP or HIV treatment
• potential drug resistance
• your ability to follow the prescribed dosing schedule

For people considering PrEP or PEP, a medical consultation can help determine whether the medication is appropriate and which regimen should be used.

For people living with HIV, ART should be prescribed and monitored as part of ongoing HIV care.

HIV medication in Singapore

HIV prevention and treatment are available in Singapore through healthcare providers.

For HIV prevention, PrEP and PEP are prescription-based options that require medical assessment. The Singapore CDA advises people who wish to use PrEP or PEP to consult a doctor to determine their suitability.

For PEP in particular, timing is critical. PEP must be started within 72 hours of a possible high-risk exposure and should be started as soon as possible. The CDA advises people requiring PEP during emergencies to visit the Emergency Department of a public hospital and request it.

For people living with HIV, ART is recommended to control the virus and reduce HIV-related health risks. With consistent treatment, people living with HIV can achieve an undetectable viral load.

If you are looking specifically for HIV prevention rather than HIV treatment, Sire provides medical consultations for HIV PrEP and PEP.

When should I speak to a doctor about HIV medication?

You should seek medical advice if:

• you are considering starting PrEP
• you want to change your PrEP dosing strategy
• you think you may have been exposed to HIV within the past 72 hours
• you have questions about PEP
• you have received a positive HIV test
• you are taking HIV medication and are concerned about side effects or drug interactions
• you have questions about your HIV treatment or viral load

HIV testing is the only way to know whether you have HIV. If you are concerned about a recent exposure, do not rely on symptoms to determine whether you have been infected.

For a potential exposure within the last 72 hours, seek medical attention promptly because PEP is time-sensitive.

Conclusion

There are several types of HIV medication, but they can be understood by looking at their purpose.

PrEP is used before potential exposure to reduce the risk of acquiring HIV. PEP is an emergency prevention option used after a potential exposure and must be started within 72 hours. ART is used to treat people living with HIV and suppress the virus.

Within HIV treatment, different antiretroviral drug classes work at different stages of the HIV life cycle. Modern treatment commonly combines medicines from different classes to achieve effective viral suppression.

If you are unsure whether you need PrEP, PEP or HIV testing, a doctor can assess your circumstances and recommend the appropriate next step.