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How does diaphragm birth control work?

Key takeaways:

A diaphragm is a non-hormonal, reusable barrier method birth control that works to prevent pregnancy, but does not protect against STIs
While some versions require a fitting with an in-person healthcare provider, there is also a version that can be fitted using a self-assessment
It’s important to discuss any discomfort with your healthcare provider, as they can help you find a better fit or more comfort

The diaphragm is a soft, dome-shaped device that fits inside the vagina and covers the cervix to help prevent pregnancy. It’s a hormone-free option that’s used with spermicide to block sperm from reaching an egg. You insert it before sex and remove it afterward, making it a flexible, reusable method that you control.

When used correctly every time, the diaphragm can be up to 94% effective, but typical use brings that closer to 83%. It doesn’t protect against STIs and can take some getting used to, especially when it comes to fit and placement.

If you’re looking for a non-hormonal method you can manage on your own, the diaphragm might be an option to consider.

How the diaphragm works to prevent pregnancy

The diaphragm is a hormone-free birth control method that combines a physical barrier with spermicide to help prevent pregnancy. Here’s how it works, step by step:

It creates a physical barrier

The diaphragm is a soft, dome-shaped silicone cup that fits snugly over the cervix—the small opening to the uterus. Once in place, it physically blocks sperm from entering the uterus and reaching an egg. Think of it as a small shield that covers the cervix during sex.

It must be paired with spermicide

On its own, the diaphragm only blocks sperm. That’s why it must be used with spermicide, a gel or cream that contains chemicals (usually Nonoxynol-9) that stop sperm from moving. Before insertion, you apply spermicide to the inside of the diaphragm dome and around the rim—this helps form a chemical barrier in addition to the physical one.

It stays in place during sex

When inserted correctly, the diaphragm fits behind the pubic bone and rests against the back of the vaginal wall. It should stay securely in place during movement or penetration. You shouldn’t feel it once it’s positioned, similar to how you don’t feel a tampon when it’s in properly.

You can insert it ahead of time

One of the benefits of the diaphragm is that it can be inserted up to six hours before sex. That flexibility means you don’t have to pause intimacy to put it in. If you have sex again or more than six hours after insertion, you’ll need to add more spermicide before each time (but you don’t need to remove and reinsert the diaphragm).

It’s removed and reused

After sex, you’ll need to leave the diaphragm in place for at least six hours to ensure the spermicide has time to work, but don’t leave it in longer than 24 hours total. Once removed, wash it with mild soap and warm water, dry it thoroughly, and store it in its case. With proper care, most diaphragms can be reused for up to two years.

How Effective is it?

Let’s break down the numbers:

Perfect use: About 94% effective at preventing pregnancy.
Typical use: Around 83% effective, reflecting real-world use where steps might be missed occasionally.
Out of 100 people using a diaphragm for a year, about 13 may experience an unintended pregnancy with typical use.

Remember, effectiveness depends a lot on how consistently and correctly you use it. If you’re comfortable and committed, your personal success rate could be higher.

Typical use versus perfect use

Perfect use means following all the directions each time: inserting the diaphragm properly, applying enough spermicide, leaving it in for at least six hours after sex, and never skipping steps. Typical use reflects real life, where sometimes spermicide might be missed or the diaphragm removed too soon.

This difference shows why getting familiar with how your diaphragm works—and practicing good habits—is so important. Products like Caya® are often recommended for their ease and comfort, but even the best diaphragm only works well if used correctly.

Factors that affect how well it works

Several things can influence your diaphragm’s effectiveness:

Changes in body weight (more than 10 pounds)
Pregnancy or pelvic surgery affecting fit
Proper spermicide use (too little reduces protection; too much may cause irritation)
Sexual positions that might dislodge the diaphragm

Regular check-ins with your healthcare provider can help ensure your diaphragm still fits well and offers good protection.

How to use a diaphragm correctly

Using your diaphragm the right way is key to staying protected. Here’s a simple guide to help you feel confident every step of the way.

Check your diaphragm

Before you start, wash your hands with soap and warm water. Hold your diaphragm up to the light or fill it with water to check for any holes or tears. Even a small rip can affect how well it works.

Apply spermicide

Use about a tablespoon of spermicide and spread it inside the dome and around the rim. This helps block sperm and keeps the diaphragm sealed against your vaginal walls.

Fold and insert

Find a comfortable position—standing with one foot on a chair, squatting, or lying down. Fold your diaphragm in half with the dome pointing down, then gently push it inside your vagina as far as it will go. It will spring open and should cover your cervix completely.

Check placement

Use your finger to feel the front rim of the diaphragm—it should be tucked up snugly behind your pubic bone. This keeps it secure during movement. You shouldn’t feel the diaphragm during daily activities or sex once it’s in place.

Wait before removing

Leave your diaphragm in place for at least six hours after sex. This gives the spermicide time to do its job. But don’t leave it in longer than 24 hours to reduce the risk of infection.

Remove carefully

To take it out, hook your finger under the front rim and gently pull it down and out. If it feels stuck, try bearing down like you’re having a bowel movement to help bring it within reach.

Clean and store

Wash your diaphragm with mild soap and warm water—avoid anything harsh or scented. Rinse well and let it air dry completely before putting it back in its case. If it’s sticky after cleaning, dust it lightly with cornstarch (not talcum powder).

Getting the right size diaphragm

Unlike condoms, which come in a few standard sizes, diaphragms need to be specially fitted to your body. This isn’t something you can do on your own—you’ll need a pelvic exam with a healthcare provider.

Pelvic exams

A well-fitting diaphragm is key to effective birth control. If it’s too small, it may slip or not cover your cervix properly. If it’s too large, it can be uncomfortable or cause irritation.

During your exam, your provider will also check for any health issues that might make a diaphragm less suitable for you. This is your chance to ask questions and get clear, practical advice about using your diaphragm with confidence.

During this quick, comfortable exam, your provider will measure your vagina and cervix to find the right size diaphragm for you. They’ll try different sizes until they find one that fits snugly, stays in place, and fully covers your cervix. You’ll also get hands-on guidance on how to insert and remove it, which can make all the difference if you’re new to using a diaphragm.

While brands like Milex® offer a range of sizes for a tailored fit, there are also one-size options like Caya® that come with a self-assessment to help you find the right fit.

When to recheck your diaphragm size

Your size can change over time. It’s a good idea to get refitted if you gain or lose more than 10 pounds, after pregnancy (even if you haven’t delivered vaginally), or following pelvic surgery. Some providers suggest annual check-ins, since even small changes in anatomy can affect fit.

If your diaphragm feels uncomfortable, slips more than usual, or doesn’t seem to be sealing properly, don’t wait to get checked. Staying proactive helps keep your birth control reliable and comfortable.

Benefits of diaphragm birth control

It’s important to find a birth control method that fits your body and lifestyle. The diaphragm offers a hormone-free, flexible option that gives you a good amount of control. Here’s what you should know about its benefits to help you decide if it’s right for you.

Hormone-free birth control

The diaphragm is a good option if you want to avoid hormones. It won’t affect your mood, weight, or menstrual cycle like hormonal methods sometimes do.

You use it only when needed—no daily pills or injections—making it perfect if you prefer more control, have less frequent sex, or may want to get pregnant in the near future.

Works well with medications and health conditions

Since the diaphragm doesn’t contain hormones, it won’t interfere with other medications or medical conditions.

Whether you’re on antibiotics, managing a chronic illness, or simply want a natural option, this method fits smoothly into your health routine without causing complications.

Reusable and cost-effective

A single diaphragm can last up to two years with proper care, making it a budget-friendly choice over time. After your initial fitting and purchase, your ongoing cost is mainly spermicide.

This reusable method also means less waste, which is great if you’re thinking about the environment.

Risks and side effects

Diaphragms are generally safe and effective, but like any birth control method, they come with some potential risks and side effects. Understanding these can help you use your diaphragm confidently and know when to reach out for support.

Vaginal irritation

Vaginal irritation is the most common side effect and may include redness, itching, or a burning feeling. This irritation can come from sensitivity to spermicide, an allergy to silicone, or simply from wearing the device.

Using too much spermicide or leaving the diaphragm in longer than recommended can make irritation worse. If you notice persistent discomfort, talk to your healthcare provider about trying a different spermicide.

Urinary tract infections (UTIs)

The diaphragm can put you at an increased risk of urinary tract infections because it puts pressure near the urethra, which might make it harder to fully empty your bladder. This can allow bacteria to grow and cause infection.

Signs of a UTI include burning during urination, frequent urges to pee, or cloudy or strong-smelling urine. To lower your risk, drink plenty of water, urinate soon after sex, and make sure to remove the diaphragm within the recommended time.

Toxic shock syndrome and safe timing

Though very rare, toxic shock syndrome (TSS) is a serious condition linked to leaving any vaginal device in too long. Never keep your diaphragm in for more than 24 hours. Setting a reminder can help you remember.

Signs of TSS include sudden high fever, vomiting, diarrhea, and a rash that looks like a sunburn. Always follow the rule: keep it in for at least six hours after sex, but no longer than 24 hours total.

Diaphragm birth control and your sexual partners

Wondering if your partner will notice the diaphragm during sex? Most don’t. When inserted correctly, the diaphragm sits over your cervix and stays out of the way. It’s designed to be discreet and comfortable for both of you.

That said, open communication about birth control can help you both feel confident and on the same page. Some partners like to be involved in the process, while others are happy to leave it to you—there’s no one right way.

If your partner can feel it

In some cases—especially during vigorous sex or certain positions—your partner might feel the diaphragm’s rim. It’s usually not uncomfortable, but if it becomes noticeable, a quick adjustment in position often helps. If it keeps happening, you might need a different size or a refresher on insertion—something your provider can help with. If you’re using Caya®, try removing and reinserting to relieve discomfort during sex.

STI protection

Diaphragms prevent pregnancy but don’t protect against sexually transmitted infections (STIs). If STI prevention is important to you, pair your diaphragm with condoms for extra protection.

Bonus: using both methods can increase pregnancy prevention, too—just make sure to stick with water-based lubricants to keep both barriers safe and effective.

Diaphragm birth control compared to other methods

Choosing the right birth control is personal, and comparing options can help you feel more confident in your decision. Here’s how the diaphragm stacks up against other popular methods.

Diaphragm vs. hormonal methods

Diaphragms don’t contain hormones, so they won’t affect your cycle, mood, or weight. They’re used only when needed, giving you flexibility and control. Unlike birth control pills or IUDs, diaphragms require more planning, but that tradeoff works well for people who want a hormone-free, on-demand method.

They also don’t interact with medications or underlying health conditions the way some hormonal options can, which makes them a good fit for certain medical needs.

Diaphragm vs. other barrier methods

Unlike condoms, which are used once and thrown away, diaphragms are reusable for up to two years. This makes them a more sustainable and cost-effective choice over time. They also offer privacy and spontaneity—you can insert it hours before sex, so it doesn’t interrupt the moment.

Compared to cervical caps, diaphragms tend to be easier to insert and remove, and they’re more widely available. They also typically stay in for a shorter time after sex, which some people find more comfortable.

Diaphragm vs. menstrual cup

While they look similar, diaphragms and menstrual cups do completely different things. A diaphragm covers the cervix and blocks sperm to prevent pregnancy. A menstrual cup collects period blood and sits lower in the vagina. They aren’t interchangeable, so it’s important to use each for its intended purpose.

That said, if you’ve used a menstrual cup before, you might find a diaphragm easier to learn. The insertion and removal techniques have a lot in common.

Cost considerations

While there’s an upfront cost for the diaphragm and possible fitting appointment, it can save money over time. You’ll only need to purchase spermicide regularly.

Compared to monthly pills or quarterly injections, this can be a more affordable long-term solution, especially for those without insurance.

Is diaphragm birth control right for you?

The vaginal diaphragm can be a great fit if you’re looking for a hormone-free birth control option that gives you control over when and how you use it. It’s best for people who are comfortable with their bodies, willing to insert the device before sex, and ready to follow the proper steps for use and care.

However, it does require a bit more hands-on involvement than long-acting methods, and it isn’t always quite as effective as some other types of birth control, especially if it’s not used perfectly every time.

As with any birth control method, the key is finding what works for your lifestyle and preferences.

Frequently Asked Questions (FAQ):

Is a diaphragm a good form of birth control?

Yes, when used perfectly with spermicide, it’s about 94% effective. With typical use, effectiveness is closer to 83%.

Why don’t people use diaphragms anymore?

More convenient and lower-maintenance options—like IUDs and implants—have become popular, but diaphragms remain a solid choice for those seeking hormone-free, user-controlled methods.

Can my partner feel the contraceptive diaphragm?

Most of the time, no. When inserted correctly, it usually isn’t noticeable to either partner.

Is a diaphragm better than an IUD?

Not quite. IUDs offer higher effectiveness and require less day-to-day involvement, but the diaphragm may be a better fit for those wanting a non-hormonal, on-demand method.

If you’d like to learn more from the comfort of home, Nurx offers convenient online consultations to help you find your best fit. Nurx providers can prescribe Caya® when medically appropriate, which does not require an in-person fitting. Ultimately, the birth control method that’s best for you is the one that fits your body and lifestyle, and Nurx providers are here to help you find what’s right for you, every step of the way.

The information provided is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon this content for medical advice. If you have any questions or concerns, please talk to a medical professional.

Services not offered in every state. Medications prescribed only if clinically appropriate, based on completion of required consultation.

Not all options discussed in the blog are available through Nurx. Please see Nurx.com for details.

Caya® may be prescribed by a Nurx-affiliated provider, but is not fulfilled through a Nurx pharmacy. Learn more at caya.us.com. All product names, manufacturer or distributor names, logos, trademarks, and registered marks (“Product Marks”) are the property of their owners and are for identification purposes only. Product Marks do not imply any affiliation, endorsement, connection, or sponsorship by their owner(s) with Nurx. If you feel pain, irritation, or notice bleeding, stop using Caya® and contact your healthcare provider. You may have an underlying issue such as an infection or sensitivity to spermicide. If diagnosed with a vaginal infection, replace your Caya® diaphragm after completing treatment.