Can I Take PrEP to Prevent HIV Only When I Need It?

Some men who have sex with men may only need to take medications intermittently to prevent HIV.

Truvada (F/TDF) is unquestionably one of the best tools for stopping the spread of HIV.

PrEP, taken once a day, reduces the risk of HIV infection from sexual activity by up to 99%.

F/TDF is a combination of two antiviral agents. Pre-exposure prophylaxis is called PrEP. Until late 2019, Truvada was the only medication approved for PrEP.

Federal Drug Administration (FDA) approved a second generic agent that will be released in September 2020, a year earlier than expected.

Descovy, another agent for daily administration is available. Gilead Sciences manufactures both Truvada and Descovy.

The cost of PrEP has been a barrier to the use of Truvada.

According to a report on NBC, a month’s supply of Truvada in the United States sells for $1,600 to $2,000, while a month’s supply of the generic version in other countries sells for only $70 a month.

Activists have pressured for the release of a generic version of Truvada to make it available to a highly vulnerable population with limited means to afford the treatment.

Intermittent use of Truvada can be an advantage for some men.

But do men who only occasionally have sex with other men (MSM) need to take HIV prophylaxis medications regularly? Is it safe for them to Truvada only when they have sex?

An updated report from the World Health Organization (WHO) suggests that for some men who have sex with men, intermittent use of Truvada may be effective.

Many men who have sex with another man do so only occasionally, and when they do, they can plan ahead. Intermittent dosing has some advantages for them.

Intermittent PrEP is a particularly good option for older people who have other medical issues (such as kidney problems) that are exacerbated by daily dosing with Truvada.

Intermittent use may benefit those who are most vulnerable but where the cost of Truvada has been prohibitive. It might also be advantageous for those who wish to take this preventive medication discretely.

ED-PrEP is recommended solely for men who have sex only occasionally and are able to plan their sexual activity in advance.

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ED-PrEP stands for Event-Driven PreP. Truvada, when taken intermittently, has proven highly effective in reducing HIV in MSM who engage in receptive or insertive anal sex. It is an alternative to daily PreP dosing, but only for some men.

At this time, the data are only available for Truvada. Descovy has not been approved for intermittent use because data are not yet in for Descovy.

Event-Driven PrEP (ED-PrEP) is also known as 2 + 1 +1.

In July 2019, WHO published an update to their earlier recommendations on oral Pre-Exposure Prophylaxis(PrEP) for men who have sex with men. WHO announced the update, called “What’s the 2 + 1 +1?”

ED-PrEP for MSM consists of a two-pill loading dose taken 24 hours before sex, another one pill 24 hours later, and a final, fourth pill taken another 24 hours later (2 + 1 + 1).

Since the initial dose must be taken two hours before sexual activity, ED-PrEP should only be used by men who can predict their sexual activity in advance.

The effectiveness is unknown for other regimens, such as taking a single pill before sex or taking PrEP four times per week.

Who might take Truvada intermittently?

ED-PrEP is recommended solely for men who have sex only occasionally and can plan their sexual activity in advance.

MSM on PrEP can switch from daily dosing to ED-PrEP, and those on ED-PrEP can move back to daily dosing if sexual activity increases.

A man who stops having sex can discontinue daily PrEP. If he returns to only occasional and predictable sex, he can re-initiate ED-PrEP.

All people at risk for HIV because of frequent sex or who have sex at unpredictable times should take daily oral PrEP.

Who should not take Truvada intermittently?

All people at risk for HIV because of frequent sex or who have sex at unpredictable times should take daily oral PrEP.

WHO does not recommend ED-PrEP for MSM who have sex more than twice a week or when sex cannot be predicted or delayed for two hours.

If a man is on ED-PrEP and returns to having sex more regularly or under less predictable circumstances, he should return to daily dosing to stay protected.

WHO does not recommend 2 + 1 + 1 for youth.

Because of insufficient evidence, ED-PrEP is not recommended for the following:

  • Women
  • Transgender women and men who have vaginal or anal intercourse with women
  • Those who can more readily adhere to daily dosing.

Supervision of treatment with Truvada

Because of concerns about kidney function and bone density, either daily dosing or intermittent use of Truvada requires regular visits with your doctor. Whether on either daily PrEP or ED-PrEP, HIV and other lab testing should be the same for all.

Men who take Truvada should have follow-up visits one month after initiating the treatment and then every three months.

Follow-up visits are to:

  • Monitor kidney function and bone density.
  • Provide testing for HIV and other sexually transmitted diseases (STDs)
  • Counsel about adherence to dosing strategy and transitioning from one form of treatment to the other.
  • Assess if HIV risk is likely to persist into the next weeks and months

Daily PrEP v. ED-PrEP

The preference for ED-PrEP over daily dosing depends on the MSM’s risk profile. Daily dosing is considered by many to be easier to use. It can be an attractive alternative for MSM who do not wish to be on the daily dosing of PrEP.

Some resist the daily PrEP dosing because of concerns about the long-term consequences of it.

Others may oppose daily dosing because of the expense. (Daily dosing can cost $1,600 to $2,000 per month if paid out-of-pocket.) Gilead, the manufacturer of Truvada, offers financial assistance to some who qualify.

Potential benefits of ED-PrEP:

  • Provides choice and convenience
  • Gives men who can anticipate, plan or delay sex an option
  • Reduces the burden of taking a daily pill
  • Saves costs
  • It may be safer for men with chronic medical conditions.

Potential risks of ED-PrEP:

  • May be difficult for some, e.g., adolescents.
  • The potential emergence of HIV drug resistance
  • Documentation of the treatment with Truvada can have unintended consequences for those who have not declared they have sex with men. Since other indications exist for the daily dosing routine, undeclared MSM may prefer to avoid this identification, since the only approved use of ED-PrEP protocol is for MSM.

The WHO update recommends education and support for both ED-PrEP and daily dosing of PrEP.

Is it safe?

Truvada is unquestionably one of the best tools for stopping the spread of HIV.

Research shows ED-PrEP offers significant protection against HIV with proper usage. Although the daily dose of PrEP is nearly 100% effective, a few case failures have been reported.

One individual seroconverted on ED-PrEP, according to a report. Some disagreement remains among doctors and researches, but the experts I consulted recommend 2 + 1 +1 when following the above guidelines.

For those with no insurance and limited means, ED-PrEP is undoubtedly a better option than no treatment.


According to this report from Yale University,

An expensive new drug for HIV pre-exposure prophylaxis (PrEP) [Descovisy] is unlikely to confer any discernible health benefit over generic alternatives and may undermine efforts to expand access to HIV prevention for the nation’s most vulnerable populations

The FDA approved the daily use of Descovy based on evidence of its “non-inferior” efficacy and lower impact on markers for bone density and kidney safety. The manufacture of both Truvada and Descovy, anticipating the entry of a generic competitor, has moved quickly to recommend that doctors switch to the new formulation.

The report says;

branded F/TAF’s [Descovy] cannot be justified by its modest benefits.

If branded F/TAF succeeds in driving out its generic competitor, PrEP expansion in the US could grind to a halt.

Full disclosure: I am a psychiatrist and do not regularly prescribe Truvada, so I consulted with some doctors who are experts.

You should consult your primary care physician, but many of them may not be aware of the safety and potential benefits of taking Truvada occasionally. You should also be conscious of the marketing campaign of the manufacturer to influence prescribers’ opinions.

This information is not provided as medical advice, but to allow for informed decision making. It is also not a promotion of any medication.

Written by

Gay father; Psychiatrist; Award-winning author FINALLY OUT. Chapter excerpt here: Top writer on Medium. Not medical advice.

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