Abstinence

Sexual abstinence is sometimes promoted as a way to avoid the risks associated with sexual contact, though STIs may also be transmitted through non-sexual means, or by involuntary sex. HIV may be transmitted through contaminated needles used in tattooing, body piercing, or injections. Medical or dental procedures using contaminated instruments can also spread HIV, while some health-care workers have acquired HIV through occupational exposure to accidental injuries with needles.
Evidence dose not support the use of abstinence only sex education. It has been found to be ineffective in decreasing HIV risk in the developed world, and dose not decrease rates of unplanned pregnancy. It is thus often recommended that those using abstinence have condoms available as a backup for protection against STIs and pregnancy.

Some groups, notably some evangelical Christians and the Roman Catholic Church, oppose sex outside marriage and object to safe-sex education programs because they believe that providing such education promotes promiscuity. Contrary to these fears, comprehensive sex education, provision of contraceptives and family planning services does not increase sexual activity. Virginity pledges and sexual abstinence education programs are often promoted in lieu of contraceptives and safe-sex education programs. This may entail exposing some teenagers to increased risk of sexually transmitted infections, because about 60 percent of teenagers who pledge virginity until marriage do engage in pre-marital sex and are then one-third less likely to use contraceptives than their peers who have received more conventional sex education.

Ineffective methods

Most methods of contraception, except for certain forms of "outercourse" and the barrier methods, are not effective at preventing the spread of STIs. This includes the birth control pills, vasectomy, tubal ligation, periodic abstinence and all non-barrier methods of pregnancy prevention.
The spermicide Nonoxynol-9 has been claimed to reduce the likelihood of STI transmission. However, a recent study by the World Health Organization has shown that Nonoxynol-9 is an irritant and can produce tiny tears in mucous membranes, which may increase the risk of transmission by offering pathogens more easy points of entry into the system. Condoms with Nonoxynol-9 lubricant do not have enough spermicide to increase contraceptive effectiveness and are not to be promoted.

The use of diaphragm or contraceptive sponge provides some women with better protection against certain sexually transmitted diseases, but they are not effective for all STIs.
The hormonal protecting methods are by no means effective against transmission of STIs, even though they are more than 95% effective against unwanted pregnancies. Most common hormonal methods are the oral contraceptive pill, depoprogesterone, the vaginal ring and the patch.
The copper intrauterine device and the hormonal intrauterine device provide an up to 99% protection against pregnancies but no protection against STIs. Women with copper intrauterine device present however a greater risk of being exposed to any type of STI, especially gonorrhea or chlamydia.

Coitus interruptus (or "pulling out"), in which the penis is removed from the vagina, anus, or mouth before ejaculation, is not safe sex and can result in STI transmission. This is because of the formation of pre-ejaculate, a fluid that oozes from the urethra before actual ejaculation, may contain pathogens such as HIV. Additionally, the microbes responsible for some diseases, including genital warts and syphilis, can be transmitted through skin-to-skin contact, even if the partners never engage in oral, vaginal, or anal sexual intercourse.

Limitations

While the use of condoms can reduce transmission of HIV and other infectious agents, it does not do so completely. One study has suggested condoms might reduce HIV transmission by 85% to 95%; effectiveness beyond 95% was deemed unlikely because of slippage, breakage, and incorrect use. It also said, "In practice, inconsistent use may reduce the overall effectiveness of condoms to as low as 60–70%".^p. 40.
During each act of anal intercourse, the risk of the receptive partner acquiring HIV from HIV seropositive partners not using condoms is about 1 in 120. Among people using condoms, the receptive partner's risk declines to 1 in 550, a four- to fivefold reduction. Where the partner's HIV status is unknown, "Estimated per-contact risk of protected receptive anal intercourse with HIV-positive and unknown serostatus partners, including episodes in which condoms failed, was two thirds the risk of unprotected receptive anal intercourse with the comparable set of partners."

Other precautions

Acknowledging that it is usually impossible to have entirely risk-free sex with another person, proponents of safe sex recommend that some of the following methods be used to minimize the risks of STI transmission and unwanted pregnancy.

• Immunization against various viral infections that can be transmitted sexually. The most common vaccines are HPV vaccine, which protects against the most common types of human papillomavirus that cause cervical cancer, and the Hepatitis B vaccine. Immunization before initiation of sexual activity increases effectiveness.
• Male circumcision and HIV: Some research has suggested that male circumcision can reduce the risk of HIV infection in some countries. The World Health Organization cites the procedure as a measure against the transmission of HIV between women and men; some African studies have found that circumcision can reduce the rate of transmission of HIV to men by up to 60%. Some advocacy groups dispute these findings. In sub-Saharan Africa, at least, condom use and behavior change programs are estimated to be more efficient and much more cost-effective than surgical procedures such as circumcision.
• Periodic STI testing has been used to reduce STIs in Cuba and among pornographic film actors. Cuba implemented a program of mandatory testing and quarantine early in the AIDS epidemic. In the US pornographic film industry, many production companies will not hire actors without tests for Chlamydia, HIV and Gonorrhea that are no more than 30 days old-and tests for other STIs no more than 6 months old. AIM Medical foundation claims that program of testing has reduced the incidence of sexually transmitted infection to 20% of that of the general population. Douching with soap and water disrupts the vaginal flora it might increase risk of infection.
• Monogamy or polyfidelity, practiced faithfully, is very safe (as far as STIs are concerned) when all partners are non-infected. However, many monogamous people have been infected with sexually transmitted diseases by partners who are sexually unfaithful, have used injection drugs, or were infected by previous sexual partners; the same risks apply to polyfidelitous people, who face higher risks depending on how many people are in the polyfidelitous group.
• For those who are not monogamous, reducing the number of one's sexual partners, particularly anonymous sexual partners, may also reduce one's potential exposure to STIs. Similarly, one may restrict one's sexual contact to a community of trusted individuals—this is the approach taken by some pornographic actors and other non-monogamous people.
• When selecting a sexual partner, some characteristics can increase the risks for contracting sexually transmitted diseases. These include an age discordance of more than five years; having an STI in the past year;problems with alcohol; having had sex with other people in the past year.
• Communication with one's sexual partner(s) makes for greater safety. Before initiating sexual activities, partners may discuss what activities they will and will not engage in, and what precautions they will take. This can reduce the chance of risky decisions being made "in the heat of passion".
• If a person is sexually active with a number of partners, regular sexual health check-ups by a doctor, and on noticing unusual symptoms seeking prompt medical advice; HIV and other infectious agents can be either asymptomatic or involve nonspecific symptoms which on their own can be misdiagnosed.

Barrier Protection

 Various protective devices are used to avoid contact with blood, vaginal fluid, semen or other contaminant agents (like skin, hair and shared objects) during sexual activity. Sexual activity using these devices is called protected sex.

Condom machine

• Condoms cover the penis during sexual activity. They are most frequently made of latex, and can also be made out of synthetic materials including polyurethane.
• Female condoms are inserted into the vagina prior to intercourse.
• A dental dam (originally used in dentistry) is a sheet of latex used for protection when engaging in oral sex. It is typically used as a barrier between the mouth and the vulva during cunnilingus or between the mouth and the anus during anal–oral sex.
• Medical gloves made out of latex, vinyl, nitrile, or polyurethane may be used as an makeshift dental dam during oral sex, or to protect the hands during sexual stimulation, such as masturbation. Hands may have invisible cuts on them that may admit pathogens or contaminate the other body part or partner.
• Another way to protect against pathogen transmission is the use of protected or properly cleaned dildos and other sex toys. If a sex toy is to be used in more than one orifice or partner, a condom can be used over it and changed when the toy is moved.

When latex barriers are used, oil-based lubrication can break down the structure of the latex and remove the protection it provides.
Condoms (male or female) are used to protect against STIs, and used with other forms of contraception to improve contraceptive effectiveness. For example, simultaneously using both the male condom and spermicide (applied separately, not pre-lubricated) is believed to reduce perfect-use pregnancy rates to those seen among implant users. However, if two condoms are used simultaneously (male condom on top of male condom, or male condom inside female condom), this increases the chance of condom failure.
Proper use of barriers, such as condoms, depends on the cleanliness of surfaces of the barrier, handling can pass contamination to and from surfaces of the barrier unless care is taken.
Studies of latex condom performance during use reported breakage and slippage rates varying from 1.46% to 18.60%. Condoms must be put on before any bodily fluid could be exchanged, and they must be used also during oral sex.
Female condoms are made of two flexible polyurethane rings and a loose-fitting polyurethane sheath. According to laboratory testing, female condoms are effective in preventing the leakage of body fluids and therefore the transmission of STIs and HIV. Several studies show that between 50% and 73% of women who have used this type of condoms during intercourse find them as or more comfortable than male condoms. On the other hand, acceptability of these condoms among the male population is somewhat less, at approximately 40%. Because the cost of female condoms is higher than male condoms, there have been studies carried out with the aim of detecting whether they can be reused. Research has shown that structural integrity of polyurethane female condoms is not damaged during up to five uses if it is disinfected with water and household bleach. However, regardless of this study, specialists still recommend that female condoms are used only once and then discarded.

Non Penetrative Sex

A range of sex acts, sometimes called "outercourse", can be enjoyed with significantly reduced risks of infection or pregnancy. U.S. President Bill Clinton's surgeon general, Dr. Joycelyn Elders, tried to encourage the use of these practices among young people, but her position encountered opposition from a number of outlets, including the White House itself, and resulted in her being fired by President Clinton in December 1994.
Non-penetrative sex includes practices such as kissing, mutual masturbation, rubbing or stroking and, according to the Health Department of Western Australia, this sexual practice may prevent pregnancy and most STIs. However, non-penetrative sex may not protect against infections that can be transmitted skin-to-skin such as herpes and genital warts.

Avoiding physical contact

Known as autoeroticism, solitary sexual activity is relatively safe. Masturbation, the simple act of stimulating one's own genitalia, is safe so long as contact is not made with other people's bodily fluids. Some activities, such as "phone sex" and "cybersex", that allow for partners to engage in sexual activity without being in the same room, eliminate the risks involved with exchanging bodily fluids.