How Effective is Phexx, the Non-Hormonal Birth Control Gel?

Phexx (lactic acid/citric acid/potassium bitartrate) is a hormone-free birth control gel the FDA approved in May 2020. Unlike other forms of birth control that you need to use regularly on a set schedule, you can use Phexx as needed, similar to spermicide or condoms. It’s available by prescription only and is 86% effective when used within an hour before having sex.

But how does Phexx stack up compared to other forms of birth control? 

What is Phexx?

Phexx is a birth control gel that you’ll place in your vagina no more than 1 hour before sex. It requires a prescription, but it’s hormone-free and isn’t the same as a spermicide. Each dose comes in an applicator tube that’s prefilled with the right amount of Phexx gel for each use. You’ll need a dose of Phexx each time that you have sex — even if it’s within an hour of your first dose.

How effective is Phexx?

If you use Phexx birth control gel perfectly, it’s 93% effective. So around 7 in 100 women will become pregnant while using it. But no one is perfect — people may make mistakes every now and then when using Phexx. In studies, it was shown to be around 86% effective. Keep in mind that you can combine Phexx with other birth control methods, such as condoms. This may be more effective at preventing pregnancy than using Phexx alone. 

How does Phexx work?

Phexx works by affecting the sperm’s ability to move through the vagina.

Normally, the vagina is an acidic environment. When semen enters the vagina, the pH of the vagina goes up, which makes it less acidic. This is a better environment for sperm. Phexx contains the ingredients lactic acid, citric acid, and potassium bitartrate. When placed in the vagina, they keep the pH low, so the vagina stays acidic. Sperm can’t move as well in an acidic environment.

Phexx is also formed as a thick gel that sticks to the walls of the vagina. This also makes it difficult for sperm to travel. Slowing down the sperm makes it less likely to reach and fertilize an egg. 

What is the difference between Phexx and spermicides?

Spermicides work directly on the sperm to prevent them from being able to move through the vagina. Most contain the active ingredient nonoxynol-9. Spermicides are available in many forms, including foams, vaginal suppositories, and creams or gels. But compared to other methods of birth control, spermicides are one of the least reliable. They’re only 72% effective at preventing pregnancy.

Unlike Phexx, which you can insert it right before having sex, some spermicides must be inserted at least 10 to 15 minutes beforehand. Spermicides can also irritate the vagina and may raise your risk of contracting HIV if your partner has the virus. But spermicides are available over the counter (OTC) without a prescription, unlike Phexx.

Phexx side effects

Like any medication, there are side effects that you may experience if you use Phexx. Some of the common side effects of Phexx include:

• Bacterial vaginosis (vaginal infection)

• Vaginal burning, itching, or pain 

• Urinary tract infections (UTIs)

• Vaginal discharge

• Vaginal yeast infection

Serious side effects are rare, but they’re also possible with Phexx. If you get frequent UTIs, Phexx can make them worse. They may also turn UTIs into kidney or bladder infections more easily. So you should avoid Phexx if you have a history of UTIs or other urinary tract problems.

Is Phexx a better option than vaginal contraceptive film (VCF) for preventing pregnancy?

As mentioned, spermicides come in many forms, including vaginal contraceptive films (VCFs). You also insert VCFs into the vagina before sex. But since they come as a solid film, they’re less messy than other forms of spermicide. But like other spermicides, they’re still only about 72% effective compared to Phexx’s 86% effectiveness.

Keep in mind that VCFs do last slightly longer than Phexx. You can insert them up to 3 hours before sex, as opposed to Phexx’s 1 hour limit. But you’ll still need a new film each time you have sex.

Is Phexx more effective than hormonal birth control like the pill?

No, it’s not. Hormonal birth control can range from being 91% to over 99% effective. Of these, intrauterine devices (IUDs) and the hormonal implant Nexplanon (etonogestrel) are the most effective forms of birth control.  Less than 1 in every 100 women become pregnant when using these forms of birth control. 

Some types of hormonal birth control also have non-contraceptive benefits. This includes things, such as menstrual cycle regulation, improvements in acne, and lower endometrial and ovarian cancer risks. Although Phexx does not have these advantages, it does have some of its own. You can stop using it at any time, and you can choose when you use it. 

Is Phexx still effective if I use it after sex rather than before?

No. Phexx is only effective if used before having sex. As previously mentioned, Phexx works by slowing down the sperm to prevent it from reaching the egg. So using Phexx after sperm have entered the vagina won’t work as well. It won’t be able to create the sticky barrier to slow the sperm down. And some sperm may have already moved through the vagina and towards the egg.

You can insert Phexx into the vagina with the provided applicator up to one hour before having sex. You can also use it right before intercourse — there’s no waiting needed. But you should repeat this process every time you have sex. And you’ll also need to insert another dose of Phexx if you didn’t have sex within an hour of using it, but you still plan to have sex soon.

What factors make Phexx less effective?

While there’s not much information available on this, using Phexx incorrectly will definitely cause it to be less effective. Check out this easy step-by-step guide on how to use it, and don’t be afraid to ask your provider if you still have more questions. Be careful when opening the applicator, so you don’t accidentally press down on the plunger and lose medication. Make sure to insert the applicator far enough into the vagina, and press all the way down on the plunger to administer the full dose.As you continue using Phexx, you will get better at inserting and applying it, allowing it to be as effective as possible.

As with other types of birth control, some people might worry that Phexx is less effective if you are over a certain weight. Thankfully, this is not the case. Phexx was researched in people of various weights and found to be similarly effective.

You can also use Phexx at any point during your menstrual cycle. You can even use it as soon as you get the OK from your provider to have sex after childbirth, abortion, or miscarriage.

How effective is Phexx at preventing STIs?

Unfortunately, Phexx does not provide protection against sexually transmitted infections (STIs), including HIV. Only condoms can help prevent them.

But unlike spermicides, Phexx won’t raise your risk of getting an STI.

Can I use Phexx if I have a vaginal or urinary tract infection?

Yes. You can use Phexx at the same time as other vaginal medications, including miconazole (Monistat) for yeast infections and metronidazole (Metrogel-Vaginal) for bacterial infections. But it’s always a good idea to avoid having sex until your vaginal infection is gone.

If you currently have or recently had a urinary tract infection (UTI), you should avoid using Phexx, as your infection could get worse or come back. As mentioned, if you’re prone to UTIs or get them often, Phexx may not be the best choice for you.

If you have any questions or concerns, talk with your healthcare provider or pharmacist. They can help you decide if Phexx is safe to use.

What other types of birth control can I combine with Phexx? 

You can use Phexx in addition to most hormonal birth control, like the pill or the patch, to further lower your chance of getting pregnant. You can also use it with several types of condoms, as well as with spermicides and diaphragms. 

But you should avoid using Phexx if you use vaginal birth control rings, like Nuvaring (etonogestrel/ethinyl estradiol).

How to save on Phexx

There are ways to save on Phexx, which is only available as a brand-name prescription medication. GoodRx can help you save money on your prescription. If you have commercial insurance, you may be eligible to pay as little as $0 for your first fill of Phexx by using a copay savings card from the manufacturer. Each refill after that may cost as low as $25 with this savings card.

Why trust our experts?

Written by:

Ross Phan, PharmD, BCACP, BCGP, BCPS

Ross Phan is a board-certified clinical pharmacist. She has roughly two decades of healthcare experience — with most of her experience being pharmacy related.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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