Avoiding things that can change the natural balance of your vagina or cause irritation is the best way to keep your vagina healthy.
How can I avoid getting vaginitis?
Everyone’s body is different, so the things that lead to vaginitis for some people don’t always cause problems for others. But in general, anything that changes the chemical balance in your vagina can lead to vaginitis.
Allergic reactions or sensitivity to different products, materials, or activities can also cause vaginitis. Here are a few ways to keep your vulva and vagina healthy:
Don’t use scented tampons and pads, vaginal deodorants, and perfumed "feminine hygiene" products. (If you’re worried about the way your vagina smells, your doctor can let you know if it’s normal or not).
Stop using any perfumed bath products (like soap or bubble bath), laundry products, and scented or colored toilet paper if they irritate your skin.
Don’t douche — douching washes away the good, healthy stuff in your vagina and throws off your vagina's natural balance. And if you already have an infection, douching can make it worse. Vaginas are self-cleaning, so you don’t need to clean the inside of your vagina. Washing your vulva with mild, unscented soap or just plain water is the healthiest way to clean your genitals. Vaginitis has nothing to do with how clean you are, so bathing or douching won’t cure vaginitis.
Vaginitis develops more quickly when your vulva is moist, so keep your genital area as dry as possible. Don’t sit around in a wet bathing suit or damp clothes, and don’t wear pants that are uncomfortably tight.
Rinse your vulva with mild soap and water when you shower, and dry after. Wear cotton or cotton-crotch underwear — they breathe better and can help keep your vulva dry. And change your underwear daily.
Change your tampons and pads every 4-8 hrs. Wash menstrual cups and sex toys carefully according to their instructions.
If germs from your anus get into your vagina, they can cause an infection. Wipe carefully after pooping to avoid spreading germs to your vulva. If a finger, sex toy, or penis goes into your butt, wash it carefully before it touches your vagina (or use a new condom over it).
Certain types of lubricants and spermicide may cause irritation for some people — stop using them or try a different brand if you have a reaction. If you’re allergic to latex, you can use polyurethane, polyisoprene, or nitrile condoms (they’re made from soft plastics and are latex-free).
Get to know your genitals. Look at your vulva with a mirror, and pay attention to your regular smells and vaginal discharge. It’s normal for discharge to change a little bit throughout your menstrual cycle. But knowing your body well is the best way to tell if something’s wrong, so you can get treatment as soon as possible if you need it.
Can you get vaginitis from having sex?
Most of the time vaginitis isn’t spread through sex. But sometimes vaginitis is caused by a sexually transmitted infection — trich is a very common STD that’s passed easily during sexual contact and often causes vaginitis.
Bacterial vaginosis and yeast infections aren’t sexually transmitted. But sometimes your body chemistry can have a bad reaction to another person’s semen or natural genital yeast and bacteria, which can mess up the normal balance in your vagina. And studies have shown that having sex with a new partner, or multiple partners, may make you more likely to get BV.
Sex can also lead to vaginitis if you have an allergy or sensitivity to certain types of lubes, condoms, or sex toy materials. (If you’re allergic to latex, you can use polyurethane, polyisoprene, or nitrile condoms.) And lots of friction or roughness during vaginal sex may cause inflammation and discomfort if the lining of your vagina gets irritated
Source: How do I prevent vaginitis? https://www.plannedparenthood.org/learn/health-and-wellness/vaginitis/how-do-i-prevent-vaginitis