For series such as Sentinel or X-Files, set in the current time, each writer has to make the choice of whether or not to follow safe sex guidelines. Since we are writing fiction, the author can choose not to include the HIV virus in their universe. I have no problem with stories that do not feature the use of condoms. But if you are going to stick to safe sex, please get it right.

What is safer sex anyway? We use the word safer because all sex can have consequences -- from emotional consequences to diseases and pregnancy.

The basic rule is: Come on me, not in me.

The single most effective thing you can do to stay healthy while being sexually active is to use latex condoms for any intercourse (whether vaginal or anal). All condoms are not made alike; men should experiment with different brands until they find the one they like best (many men prefer Kimono MicroThins, which also taste fine for fellatio if you get them without Nonoxynol-9). When you put on a condom, pinch its tip as you unroll it (all the way down!) to prevent an air bubble from forming in the reservoir tip. For intercourse, you should then put some water-based lube (such as I-D, ForPlay, Wet, Probe, or Astroglide) on the outside of the condom for comfort, mutual pleasure, and to keep the condom from tearing during sex (some men find that more sensation is transmitted to them if they put a small amount of water-based or silicone-based lube INSIDE the tip of their condom before putting it on). It's very important for men to hold onto the base of their condom as they withdraw (after becoming soft) so it doesn't slip off.

For a while, health experts were recommending that people choose safer sex products with Nonoxynol-9 to protect against HIV transmission; current evidence suggests that Nonoxynol-9 isn't nearly as effective at HIV prevention as it is at contraception, and if you have a sensitivity or allergy to this substance (as many people do) regular exposure to it might actually decrease your level of protection against HIV by irritating delicate vaginal or (especially) anal tissues.

If a condom fails during vaginal or anal intercourse, the receptive partner shouldn't douche; if any Nonoxynol-9 contraceptive foam is handy it might help for him or her to insert it and leave it in for about 15 minutes, and it would certainly help to immediately remove the condom from inside the vagina or anus if it was left there. Men can give themselves a little extra protection after potentially being exposed to an STD by immediately visiting the restroom, urinating, and then possibly washing their genitals with an anti-bacterial soap. If unwanted pregnancy is a possible outcome of the condom failure, you should call 1-888-NOT-2-LATE to find out about emergency contraception in your area.

It should be obvious that a new condom needs to be used for each new partner, and that condoms should not be reused. If you're going to switch from anal intercourse to vaginal intercourse, you should put on a new condom to avoid causing vaginal infections.

Opinions differ on the use of safer-sex barriers for oral sex. It's clear that herpes can be transmitted from genitals to mouth or mouth to genitals during unprotected oral sex, but some people feel the risk is acceptably low outside of the most infectious period (which starts with the tingling "prodrome" sensations that precede an outbreak and continues to two weeks after the sores go away). You can on rare occasion pick up some types of bacterial infections of the throat by going down on someone who currently has a bacterial STD, but these can be easily cured with antibiotics once identified (at the time we wrote this guide a few strains of gonorrhea had just appeared that were resistant to the usual antibiotics, but these could still be eliminated by switching to a different set of antibiotics). Hepatitis B can be transmitted via unprotected oral sex, but if you're worried about this disease you could just get vaccinated against it.

At the time this guide was written there were no clear cases of anyone becoming infected with HIV through RECEIVING unprotected oral sex. There ARE recorded cases of people becoming infected with HIV through GIVING unprotected oral sex, but the risk of transmission via this route is apparently quite low if your gums (and lips, mouth, and throat) are healthy, if you don't let men come in your mouth, and if you don't perform cunnilingus on a woman while she is menstruating.

Some sex educators recommend NOT flossing or brushing your teeth for two hours before giving unprotected oral sex (use Listerine or some other anti-bacterial mouthwash if you're concerned about bad breath or just want to freshen up), and others recommend quickly looking over the genitals you're about to go down on for signs of contagious STDs (including genital warts, which can on rare occasions be transmitted from genitals to mouth). If your policy for performing unprotected fellatio is to not let your partner come in your mouth and he does so anyway, it's better to immediately spit than to either wait or swallow, and it may help (especially for bacterial STDs) to then go use an anti-bacterial or peroxide mouthwash. Pre-cum can contain HIV, and although not letting men come in your mouth SIGNIFICANTLY reduces your already low risk to even lower (theoretical?) levels, if you are concerned about becoming infected via pre-cum while performing fellatio you have two risk-reduction options: not taking the head of his penis in your mouth and using barriers for oral sex.

If you decide that your personal standards include using barriers for oral sex, this means using latex condoms (without Nonoxynol-9, in this case) for fellatio; one interesting trick for those who are only concerned about infected semen and pre-cum is to apply the condom inside-out so that it only covers the head of the penis. Using barriers for oral sex also means using either Saran wrap or one of those "Glyde" or "Lixx" oral sex barriers for cunnilingus; in this case, put a little water-based lube on your partner's side of the barrier to increase the sensation transmitted to her. The same barrier techniques used for cunnilingus can be used for analingus, where they should be considered essential if the person doing the licking isn't immunized against hepatitis A.

Gay men have had a decade to get used to safe sex. We've had to each make our own choices about which behaviors we will still indulge in, and which we will modify. Oral sex without a condom is seen as being an acceptable risk by most men. Anal sex without a condom is not (although "barebacking" is becoming more common because basically people are stupid). Frottage (also known as "The Princeton Rub"), mutual masturbation, and other forms of non-penetrative sex are also popular.

Some people believe that all stories should include safe sex, so as to not set a bad example for the readers. There is some validity to this view, but since the people reading our stories are supposed to be over the age of consent anyway, they should already know about safe sex.

For more about safe sex, check out one of these sites.

• safersex.org
• The Coalition for Positive Sexuality
• The Stop Aids Project
• The Society for Human Sexuality

Whatever decision you make about your own behavior, make it an informed one.