They sit in the same aisle as school supplies in CVS and come in different colors, flavors, textures and sizes.

With their bright packaging, condoms appear to be more novelty than practical. However, with the risk of incurable sexually transmitted infection and pregnancy, condoms are as much for safety as they are for fun.

One in two sexually active individuals will contract an STI by the age of 25, according to the American Social Health Association, a national non-profit organization devoted to preventing STIs.

With all the different styles and brands of condoms available, finding the right kind can be difficult. The Post investigated how to pick the right condom.

Latex, lambskin and lubrication

When used consistently and correctly, the male latex condom can reduce the risk of many STIs including HIV, gonorrhea and herpes, according to the Centers for Disease Control and Prevention.

Latex condoms are the most effective for protecting against STIs because they do not have pores, unlike condoms made from lambskin, said Maxwell Ciardullo, information coordinator for the Sexuality Information and Education Council of the United States, an organization that promotes sexual education, health and rights.

The pores in lambskin condoms allow for pathogens such as the HIV virus to pass through, Ciardullo added.

While all latex condoms are an effective barrier to pathogens, an ultra-thin latex condom may be more prone to breaking than a thicker latex one, said Amanda Childress, assistant director of health promotion at Ohio University.

This isn’t the case for all ultra-thin condoms. The label on the package will tell you if the effectiveness is decreased, Childress said.

Unlike the thickness of a condom, texture should not change the effectiveness, said Kaleena Schmidt, graduate assistant for health promotion.

The only purpose of texture is to increase sensations for one or both partners, Schmidt said.  

Another option with latex condoms is spermicidal lubricant, which has begun to come under debate. It’s effective in reducing pregnancy, but many people are allergic to it, and it can cause lesions, leaving a person more susceptible to STIs, Childress said.

However, with all latex condoms and especially the ultra-thin ones, a water-based lubricant should be used to prevent breakage, Childress said.

Going natural

For people who are allergic to latex, there are condoms made from a blend of polyethylene and polyurethane or lambskin.

Though all three types of condoms do effectively prevent pregnancy, polyurethane condoms are recommended over lambskin condoms because, like latex, they are nonporous and therefore more effective in STI prevention, Schmidt said.

Polyurethane condoms have a similar feel to a plastic bag and will make more of a crackling noise, she said.

Also, they are more expensive and some people complain that they reduce sensation, she added.

For people who are with only one partner and more concerned about pregnancy than STIs, lambskin condoms can be an alternative to latex.

Some couples use them because they feel more natural than the other alternatives, Schmidt said.

For couples who are opposed to animal products, some companies have started making vegan condoms.

A vegan condom is made from latex but does not use casein, a derivative of cow’s milk, during production, said Barbara Lippert, president of Glyde USA Incorporated, which is a producer of the materials for vegan condoms.

Latex is considered vegan because it is a natural product that comes from rubber trees, Lippert said.

Vegan condoms are FDA approved and have the same safety ratings as other latex condoms, she said.

They are not sold in drugstores but are available online, Lippert added.

The Magnum myth

Besides material, another consideration to make when buying condoms is size.

“You can always wear regular (size) condom … no one needs a magnum,” Schmidt said.

The problem is when people use a condom that is too large and it slips, which increases the risk of contracting an STI or getting pregnant, she said.

A properly fit condom is more comfortable for the man, Schmidt added.

More important than brand or type of condom is using it correctly, Ciardullo said.

In 2002, 40 percent of college-age males did not leave space in the tip of the condom, according to a study conducted by  the American Sexually Transmitted Diseases Association.  

Many condoms now leave space in the tip, but if there isn’t, pinch it off, Schmidt said.

This is important because semen is ejected at 25 to 30 miles per hour, so it needs a place to go, she said.

The ASTD study also found that 30 percent placed the condom on upside down and a third experienced breakage or slippage of the condom during sex.

If a condom is placed on upside down, a new one should be used because, otherwise, there can be a transfer of fluids between partners, Ciardullo said.

Even with mistakes, though, people are safer with a condom than without one.

There is no such thing as safe sex, but some protection is always better than none, Schmidt said.