Honestly it depends. I've had a yeast infection for two months now. It's slowly going away though. I've been able to get rid of two of my symptoms which are the itching and burning, but i still have swelling and discharge. Monistat and diflucan prescribed by the doctor did not work. So like the other person said your body could be resistant to the medication. I just been doing natural things. Here's what i've doing.
Changing my eating habits because it does have a direct link to yeast infections. Limit your intake of sugar and carbs(pasta, bread, rice, cookies, pastries, even fresh fruit etc) because these feed yeasts causing them to grow. Eat a diet rich in lean protein and veggies. Eat plain yogurt(no added sugar) because it contains L.acidophilus, the good bacteria we need for healthy vaginal flora. Even if you're on medication, if you're still taking in alot of carbs and sugar you're not going to heal any faster because you're letting the yeast continue to grow.
Building my immune system by taking vitamins A,D,C, and Folic Acid supplements
Taking garlic, grapefruit seed extract, and echinacea/goldenseal herb supplements. They act as natural antibiotics with antibacterial and antifungal properties. You can also incorporate raw garlic into your diet for better results.
Take probiotics/acidophilus supplements.
I recommend you research yeast infections and everything i mentioned linked to it like diet, vitamins, and supplements. What I have been doing has been working, but you have to have patience because it's not always a quick fix. Your body has to have a healthy immune system to help fight infections. You have to make your partner understand if the issue is about sex.
Also, visit www.earthclinic.com click on ailments and then yeast infection. There are natural home remedies listed there as well.