Condoms, Femidoms & Dental Dams: A Guide to Safe Sex

Why barrier methods are so important

Barrier methods prevent direct contact between mucous membranes and bodily fluids – and thus the transmission of pathogens. They are the only contraceptive method that protects against both unwanted pregnancy and STIs.

Double protection

According to the WHO and RKI, condoms, when used correctly, offer a high level of protection against HIV (approximately 80–95%) as well as against chlamydia, gonorrhea and other STIs transmitted through bodily fluids.

No hormones, no side effects

Unlike hormonal contraceptives, barrier methods do not interfere with the hormonal balance. They are well-tolerated by most people and free of systemic side effects.

Widely available

Condoms are available without a prescription in pharmacies, drugstores, and supermarkets. Female condoms and dental dams are available online and in specialty stores.

The condom (external condom)

The classic condom – also known as an "external condom" or "penile condom" – is the best-known and most widely used barrier method worldwide. It is usually made of latex, polyurethane, or polyisoprene and is rolled onto the erect penis.

effectiveness

With perfect use, the Pearl Index is around 2 (2 out of 100 people become pregnant within one year). With typical use, it rises to 12–18 – mostly due to user errors such as incorrect application or use without sufficient lubricant.

STI protection

Condoms reduce the risk of HIV transmission by 80–95% (Cochrane Review, 2012). They also provide good protection against gonorrhea, chlamydia, and trichomoniasis. Protection against HPV and herpes is limited, as these can also be transmitted through skin-to-skin contact.

materials

Latex: Most widely used, elastic and reliable. Polyurethane/Polyisoprene: Latex-free alternatives for allergy sufferers. Lambskin: Does not protect against STIs, as its microporous structure can allow viruses to pass through.

Proper use

Slip it on before first physical contact. Leave the reservoir at the tip free. Use only water-based or silicone-based lubricants (oils will damage latex). After ejaculation, hold it in place and carefully pull it off.

Avoid common mistakes

Incorrect size: Too tight = risk of tearing; too loose = slipping off. Condoms are available in different sizes (49–69 mm nominal width).
Improper storage: Heat, cold, and direct sunlight will damage the material. Do not store in a wallet.
Expired expiration date: The material becomes porous. Always pay attention to the date.
Double use: Never use two condoms on top of each other – the friction increases the risk of tearing.

The female condom (internal condom)

The female condom – also called "female condom" or "internal condom" – is inserted into the vagina or anus. It is made of nitrile or polyurethane and has two flexible rings: an inner one for fixation and an outer one that remains outside.

More self-determination

The female condom can be inserted by the receptive person themselves – regardless of whether their partner has an erection. This allows for greater control over their own protection and it can be used up to 8 hours before sex.

Also suitable for anal sex

The female condom can also be used anally. The inner ring is removed to facilitate insertion. Studies show good acceptance and protective effect during anal intercourse.

Effectiveness & Protection

The Pearl Index is approximately 5 with perfect use and 21 with typical use. The female condom protects against HIV and most STIs. Because the outer ring covers parts of the vulva, it can also offer partial protection against HPV and herpes.

Good to know:

The female condom is latex-free (usually made of nitrile) and therefore suitable for people with a latex allergy. It can be used with all types of lubricants – including oil-based products.

Dental dams (dental dams)

Dental dams are thin, rectangular sheets made of latex or polyurethane, originally developed for dentistry. They are placed over the vulva or anus during oral sex and prevent direct mucosal contact.

Application

Lay the cloth flat over the vulva or anal area. Do not stretch or turn it over. Use a new cloth for each new area (e.g., from vulva to anus). Single use only – dispose of afterwards.

Protection against STIs

Dental dams reduce the risk of transmission of herpes (HSV), HPV, gonorrhea, chlamydia, and syphilis during oral sex. Since many of these infections are asymptomatic, protection is advisable even for partners who appear "healthy."

DIY alternative

No dental dam on hand? An unlubricated condom can be cut open and laid flat. Simply cut off the tip and base, then cut lengthwise – and your improvised dental dam is ready.

Availability

Dental dams are available in pharmacies, online shops, and at AIDS service organizations. They come in various flavors and colors. The cost is approximately €1–3 each.

Barrier methods compared

Which method is suitable for which situation? The following overview helps with orientation – based on scientific data on effectiveness and scope of application.

method	Suitable for	STI protection	Pearl Index	Special features
Condom (external)	Vaginal and anal sex	High (HIV, Chlamydia, Gonorrhea)	2–18	Most common; various sizes
Femidom (internal)	Vaginal and anal sex	High; also partially HPV/Herpes	5–21	Latex-free; can be used up to 8 hours in advance
Dental Dam	Oral sex (vulva, anus)	Medium-high (Herpes, HPV, Gonorrhea)	–	Single use only; DIY from a condom possible.

Important:

The Pearl Index refers to contraceptive effectiveness (pregnancy prevention) and is not applicable to dental dams. STI protection depends heavily on correct use – studies show that user error is the most common reason for reduced effectiveness.

Combined protection: barrier methods + other strategies

Barrier methods offer good, but not absolute, protection. For optimal safety, professional societies recommend a combination of several prevention strategies – depending on the individual situation.

Additional protective measures

Regular STI testing is especially important if you have multiple partners or unprotected sex. Many infections are asymptomatic and are only detected through testing.
HPV vaccination: Protects against the most common cancer-causing HPV types. Recommended by the STIKO (Standing Committee on Vaccination) for all adolescents (9–14 years), but also beneficial later in life.
PrEP (pre-exposure prophylaxis): Daily medication that reduces the risk of HIV infection by over 99%. Prescription required; costs are often covered by health insurance.
Open communication: Discuss STI status, recent tests, and protection preferences. Studies show that open communication reduces risky behavior.
Hepatitis B vaccination: part of the standard vaccinations; protects against a commonly sexually transmitted viral infection.

Myths & Facts about Barrier Methods

Many half-truths circulate about condoms and other barrier methods. Here we debunk the most common myths – based on scientific evidence.

"Condoms keep tearing"

Fact: When used correctly, the tear rate is less than 2%. Most tears are caused by incorrect size, expired material, or oil-based lubricants in latex condoms.

"Two condoms are safer"

Fact: The opposite is true. Friction between two condoms significantly increases the risk of tearing. A single, properly sized condom is much safer.

"Oral sex is safe"

Fact: STIs can also be transmitted during oral sex – especially herpes, HPV, gonorrhea, and syphilis. Dental dams or condoms reduce this risk.

"Femidomes are complicated"

Fact: After 2-3 uses, most users report easy handling. Insertion is similar to that of a tampon and can be done calmly before sex.

"Condoms reduce sensation"

Fact: Ultra-thin condoms (0.01–0.05 mm) transmit body heat and sensations very well. The right size and sufficient lubricant further enhance the experience.

"I can tell when I have an STI."

Fact: Many STIs, such as chlamydia, HPV, or HIV, are initially asymptomatic. You can be infected and transmit it to others without knowing it. Regular testing is therefore important.

Conclusion: Protection is self-care

Condoms, female condoms, and dental dams are effective tools for safe sex. They protect not only against unwanted pregnancy but also against many sexually transmitted infections. The key lies in correct use and choosing the appropriate method for each situation.

Sexual health means making informed decisions – for yourself and your partners. Barrier methods are an important component, which can be complemented by regular testing, vaccinations, and open communication.

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