HIV prevention is no longer limited to condoms and testing. People who do not have HIV can also use medicines that significantly reduce their chance of acquiring the virus.
One of these options is oral PrEP.
PrEP stands for pre-exposure prophylaxis. “Pre-exposure” means the medicine is used before a possible HIV exposure, while “prophylaxis” means prevention.
Oral PrEP is intended for people who do not have HIV but may experience ongoing or repeated exposure to the virus. It is not HIV treatment, and it is different from emergency medicine taken after a recent exposure.
Nigeria approved PrEP for HIV prevention in 2016 and has included it within national HIV prevention planning and communication strategies.
This article explains how oral PrEP works, who may benefit from it, what usually happens before it is started and how it differs from PEP, antiretroviral treatment and injectable PrEP.
What Is Oral PrEP?
Oral PrEP is an HIV prevention medicine taken by a person who has tested negative for HIV.
The medicine builds protective levels of antiretroviral drugs in parts of the body through which HIV could enter. If exposure occurs while sufficient medicine is present, PrEP makes it much harder for the virus to establish a permanent infection.
PrEP should be part of a broader prevention approach that may also include:
Regular HIV testing
Condoms
Screening and treatment for sexually transmitted infections
Sterile injecting equipment
Treatment for partners living with HIV
Sexual and reproductive-health services
Accurate information about HIV transmission
WHO recommends oral PrEP as an HIV prevention choice for people who may experience substantial exposure to HIV.
Readers who need a basic explanation can begin with How Is HIV Transmitted? Facts, Risks and Common Myths Explained.
Internal link: Add the article URL after publication.
How Does Oral PrEP Prevent HIV?
HIV must make copies of itself after entering the body before it can establish infection.
The medicines used for oral PrEP interfere with this replication process. When PrEP has been taken consistently enough to produce protective drug levels, HIV may be stopped before it becomes established.
PrEP does not create a permanent shield. Its protection depends on:
Starting it appropriately
Taking it as recommended
Allowing enough time for protective levels to develop
Attending follow-up appointments
Testing regularly for HIV
Receiving guidance when stopping or restarting
PrEP becomes less reliable when doses are frequently missed.
How Effective Is Oral PrEP?
When oral PrEP is taken as prescribed, the possibility of acquiring HIV through sex becomes extremely low.
Its real-world effectiveness depends strongly on adherence. In other words, PrEP works best when the medicine is present in the body at the time protection is needed. CDC guidance notes that the few documented HIV infections among people with verified high adherence are rare.
PrEP does not prevent:
Gonorrhoea
Syphilis
Chlamydia
Hepatitis C
Pregnancy
Other health consequences of unsafe injections
Condoms and regular sexual-health screening may therefore remain important.
Who May Benefit From Oral PrEP?
PrEP should be considered according to a person’s circumstances, preferences and possible exposure to HIV, not according to stereotypes or labels.
A healthcare provider may discuss PrEP with someone who:
Has a sexual partner living with HIV whose viral suppression is unknown or not sustained
Has recently had sex without a condom in circumstances where HIV exposure may occur
Has had repeated need for PEP
Has been diagnosed with a sexually transmitted infection
Has sexual partners whose HIV status is unknown
Has difficulty negotiating condom use
Exchanges sex for money, housing, protection or other needs
Shares needles, syringes or other injecting equipment
Requests additional HIV protection because of personal circumstances
Is trying to conceive with a partner living with HIV and needs professional prevention guidance
Experiences ongoing concern about possible HIV exposure
People should not be required to disclose every private detail before receiving respectful information about PrEP.
A person may also choose PrEP for added reassurance, even when another prevention method is being used.
What If a Partner Living With HIV Is Undetectable?
A person living with HIV who takes antiretroviral treatment and maintains an undetectable viral load does not sexually transmit HIV. This is known as Undetectable = Untransmittable, or U=U.
Some HIV-negative partners may still choose PrEP because:
The partner’s viral-load result is not current
Treatment has recently started
Viral suppression has not been confirmed
There are other sexual partners
They want an additional method they can personally control
The decision should be informed and voluntary.
A complete guide to viral suppression and U=U will be linked here after publication.
Who Should Not Start Oral PrEP Without Further Assessment?
Oral PrEP should not be started casually or shared with another person.
Further clinical assessment is particularly important when someone:
Has a positive or unclear HIV test result
May have symptoms of recent HIV infection
Has a recent exposure that may require PEP
Has known kidney disease
Has hepatitis B
Is taking medicines that may affect the kidneys
Is pregnant, breastfeeding or planning pregnancy
Has previously reacted badly to a PrEP medicine
May have acquired HIV while using PrEP
Starting PrEP when a person already has undiagnosed HIV can result in inadequate treatment and may contribute to drug resistance.
Tests Usually Performed Before Starting PrEP
The exact assessment may differ according to the medicine, the individual and national guidance.
HIV testing
A negative HIV result must be confirmed before PrEP begins.
A healthcare provider may ask about:
The date of the most recent possible exposure
Previous HIV test results
Recent use of PrEP or PEP
Fever, rash, sore throat or other symptoms that could suggest recent HIV infection
Additional testing may be needed when very recent infection is possible.
An HIV self-test can help someone learn their status, but a provider may require testing within an approved clinical algorithm before prescribing PrEP.
A guide to HIV Self-Testing in Nigeria will be linked here once published.
Kidney-function assessment
Some oral PrEP medicines are processed through the kidneys. Kidney-function assessment may therefore be recommended before starting and during follow-up, depending on the person’s age, health and selected medicine.
WHO’s PrEP implementation tools include guidance on HIV testing, creatinine or kidney assessment, hepatitis testing, pregnancy and sexually transmitted infections.
Hepatitis B testing
Some medicines used for oral PrEP also act against hepatitis B.
A person with hepatitis B should not stop these medicines without professional guidance because sudden discontinuation can sometimes lead to worsening liver inflammation.
Sexually transmitted infection screening
Screening may include tests for infections such as syphilis, gonorrhoea and chlamydia, depending on symptoms, exposure and available services.
Having an STI does not automatically prevent someone from starting PrEP. The infection should be treated appropriately while HIV prevention needs are addressed.
Pregnancy testing and reproductive-health assessment
Pregnancy testing may be offered where relevant.
Pregnant and breastfeeding women can experience HIV exposure and should not be excluded automatically from prevention services. A qualified provider should discuss the available evidence, potential benefits, health history and locally recommended options.
How Is Oral PrEP Taken?
The most widely used approach is daily oral PrEP, meaning the medicine is taken regularly according to the prescription.
Some guidelines also recognise event-driven or “2-1-1” oral PrEP for selected adults whose HIV exposure occurs through anal sex. This method is not suitable for everyone and should not be started without advice from a trained provider.
Daily PrEP may be easier for people whose possible exposure is difficult to predict or who prefer a simple routine.
The right approach depends on:
The type of possible exposure
The approved medicine
National guidelines
Health history
Ability to take tablets consistently
Personal preference
Whether the person is pregnant or breastfeeding
Hepatitis B status
Do not copy another person’s PrEP schedule or use leftover medication.
How Long Does Oral PrEP Take to Work?
Protection is not immediate after the first tablet.
Research used in current CDC guidance indicates that daily oral PrEP reaches maximum drug levels associated with protection after approximately:
Seven days for receptive anal sex
Up to 21 days for receptive vaginal sex
Up to 21 days for exposure through injecting equipment
Evidence is less precise for some other types of sexual exposure.
These timeframes should not replace personal advice. A provider may recommend using condoms or another prevention method while protective levels are developing.
Anyone with an exposure during the previous 72 hours should ask urgently about PEP rather than assuming newly started PrEP will protect against that earlier event.
Why Adherence Matters
Oral PrEP works only when enough medicine is present in the body.
Missing an occasional dose does not necessarily mean protection disappears immediately, but repeated missed doses can reduce effectiveness.
Helpful adherence strategies include:
Taking the tablet at the same time each day
Connecting it to a regular activity
Using a private phone reminder
Keeping a small supply available during travel
Collecting refills before tablets run out
Discussing side effects early
Choosing a prevention option that fits everyday life
A person who has missed several doses and recently experienced possible exposure should contact a healthcare provider promptly.
They should not double doses unless specifically instructed.
Possible Side Effects
Many people take oral PrEP without major problems.
Some people experience temporary effects when starting, such as:
Nausea
Headache
Stomach discomfort
Tiredness
Loose stools
These often improve as the body adjusts.
Some oral PrEP medicines can affect kidney function or bone mineral density in a small proportion of users. This is one reason clinical assessment and appropriate monitoring are important.
Seek medical advice when side effects are severe, persistent or worrying.
A person should not stop PrEP suddenly without discussing:
Recent possible exposures
How long protection may be needed after the last exposure
Hepatitis B status
Whether another prevention method is required
Follow-Up Testing and Monitoring
PrEP is a continuing prevention service, not simply a one-time prescription.
Follow-up commonly includes:
Repeat HIV testing
Discussion of adherence
Review of side effects
Prescription refills
Kidney monitoring when indicated
STI screening
Pregnancy and reproductive-health support where relevant
Assessment of whether the current PrEP option still suits the person
Planning for safe discontinuation or restarting
The exact schedule depends on national protocols, the selected medicine and the person’s circumstances.
Regular HIV testing is essential because PrEP alone is not a complete treatment regimen for someone who has acquired HIV.
PrEP and Sexually Transmitted Infections
Oral PrEP prevents HIV. It does not directly prevent most other sexually transmitted infections.
A person taking PrEP may still acquire:
Gonorrhoea
Syphilis
Chlamydia
Trichomoniasis
Genital herpes
Human papillomavirus
Condoms can help reduce the transmission of HIV and several other STIs.
PrEP visits also create an opportunity for:
STI screening
Treatment
Vaccination where available
Condom and lubricant provision
Sexual-health counselling
Cervical-cancer prevention services
WHO recommends integrating STI services into PrEP programmes rather than treating HIV prevention as an isolated service.
Oral PrEP Versus PEP Versus ART
| Option | Purpose | When it is used |
|---|---|---|
| PrEP | Prevent HIV before exposure | During a period when future exposure may occur |
| PEP | Reduce the chance of HIV infection after a possible exposure | Started urgently after the exposure |
| ART | Treat and control HIV | After a confirmed HIV diagnosis |
PrEP
PrEP is planned prevention for someone who does not have HIV.
PEP
PEP is emergency prevention after a recent possible exposure. It should be started as soon as possible and no later than 72 hours after the exposure.
ART
Antiretroviral treatment, or ART, is a full treatment regimen for people living with HIV.
ART protects the immune system and can reduce the viral load to an undetectable level.
PrEP and PEP should never be presented as substitutes for complete HIV treatment.
Oral PrEP Versus Injectable PrEP
HIV prevention options are expanding.
Oral PrEP
Oral PrEP involves tablets taken according to an approved schedule.
Possible advantages include:
Familiar tablet form
Ability to start and stop with clinical guidance
Wider implementation experience
Personal control over administration
Possible challenges include:
Remembering tablets
Privacy when storing medication
Regular refill needs
Pill fatigue
Difficulty maintaining adherence
Injectable PrEP
Long-acting PrEP is given through injections at scheduled intervals.
Depending on the product and national availability, options may include long-acting cabotegravir or twice-yearly lenacapavir.
Possible advantages include:
Fewer medicine-taking events
No daily tablet
Greater privacy for some users
Reduced daily adherence burden
Possible challenges include:
Clinic attendance for injections
Availability and cost
Injection-site reactions
The need to remain on schedule
Management of delayed or discontinued injections
In 2025, WHO recommended twice-yearly injectable lenacapavir as an additional HIV prevention choice.
Read more about twice-yearly lenacapavir and its potential role in HIV prevention.
The best PrEP option is the one that is medically appropriate, available and realistically manageable for the individual.
Can Oral PrEP Be Used During Pregnancy?
Pregnancy and breastfeeding can be periods of increased vulnerability to HIV infection in some circumstances.
PrEP may be considered during conception, pregnancy and breastfeeding after individual assessment. The provider should discuss:
HIV exposure
The available PrEP product
Kidney health
Hepatitis B status
Other medicines
Potential benefits and risks
Follow-up arrangements
Current clinical guidance supports discussing PrEP as an option during pregnancy and breastfeeding when HIV exposure is present.
Pregnant women should not take medicines borrowed from another person or stop prescribed PrEP without speaking with their healthcare provider.
Where Can Someone Ask About PrEP in Nigeria?
Availability can differ by state, facility and programme.
People can ask at:
Government HIV treatment and prevention centres
Public hospitals providing HIV services
Approved community HIV programmes
Sexual and reproductive-health clinics
Some key-population-friendly health services
HIV testing centres
Selected youth-friendly health services
Implementing-partner-supported facilities
NACA’s youth-focused platform describes referrals for HIV counselling, testing, self-testing and PrEP services. NACA also provides the toll-free number 6222 on supported Nigerian mobile networks for HIV information.
Before travelling, confirm that the facility currently provides PrEP and ask whether an appointment, referral or identification document is required.
Common Myths About Oral PrEP
“PrEP is only for one type of person.”
False. PrEP may benefit different people whose circumstances could expose them to HIV.
“Taking PrEP means someone has HIV.”
False. PrEP is for people who have tested negative for HIV. ART is used to treat HIV.
“PrEP encourages irresponsible behaviour.”
PrEP is a health tool. Providing effective prevention does not justify judging people’s relationships or circumstances.
“PrEP protects against every STI.”
False. PrEP prevents HIV but does not prevent most other sexually transmitted infections.
“One PrEP tablet protects immediately.”
False. Protective drug levels take time to develop.
“PrEP can be taken after an exposure.”
PrEP is mainly used before future exposure. A recent possible exposure may require emergency PEP.
“People taking PrEP no longer need HIV tests.”
False. Regular HIV testing is an essential part of safe PrEP use.
Frequently Asked Questions
Is PrEP an HIV treatment?
No. PrEP prevents HIV in people who do not have the virus. People diagnosed with HIV need a complete antiretroviral treatment regimen.
Can I take PrEP only when I plan to have sex?
Some event-driven approaches may be appropriate for selected adults and specific types of exposure, but they are not suitable for everyone. Speak with a trained provider rather than creating your own schedule.
Does PrEP protect against HIV immediately?
No. Maximum protective drug levels develop over several days and vary according to the type of exposure.
Can I use PrEP without an HIV test?
No. HIV testing is required before starting PrEP and during continued use.
Can PrEP cause HIV?
No. PrEP does not contain HIV and cannot cause HIV infection.
Can I stop PrEP when I am no longer sexually active?
Possibly, but stopping should be planned with a healthcare provider. The timing depends on the last possible exposure, the type of exposure, the medicine and hepatitis B status.
Can someone use both condoms and PrEP?
Yes. The combination provides HIV protection while condoms can also reduce the likelihood of several other sexually transmitted infections and unintended pregnancy.
What happens if I miss a dose?
Take professional advice based on how many doses were missed and whether a recent exposure occurred. Do not take multiple extra tablets without instructions.
Is oral PrEP available in Nigeria?
Yes, PrEP has been incorporated into Nigeria’s HIV prevention response, although availability may differ by location and programme.
What should I do after a recent possible HIV exposure?
Seek medical attention immediately and ask about PEP. It works best when started as soon as possible and must begin within 72 hours.
Final Thoughts
Oral PrEP gives people who do not have HIV greater control over prevention.
It is particularly useful when possible exposure is ongoing, repeated or difficult to predict. Its effectiveness depends on confirming an HIV-negative status, selecting an appropriate regimen, taking it consistently and attending follow-up appointments.
PrEP does not replace respectful relationships, testing, condoms, STI care or treatment for people living with HIV. It adds another highly effective option to the HIV prevention toolkit.
Anyone interested in PrEP should speak with a trained healthcare provider or approved HIV prevention service. The conversation should be confidential, respectful and based on individual circumstances rather than assumptions.
Author: Adeyinka Joseph Alonge is a public health professional, researcher and writer with interests spanning health, science, technology, personal development and practical knowledge for everyday life.
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