Brief Answer:
Detail below.

Detailed Answer:

Hello,

Common side effects of cephalexin include:

diarrhea,
dizziness,
tiredness,
headache,
stomach upset,
abdominal pain,
joint pain,
vaginal itching or discharge,
nausea,
vomiting,
itching,
swelling, and
rash.
So vaginal dryness and yeast infection are not side effects of cephalexin.
If you have these symptoms than stop taking cephalexin and do following

You or your doctor inserts this soft, flexible ring into your vagina where it releases a steady stream of estrogen directly to the tissues. The ring is replaced every 3 months.
You use a disposable applicator to put a tablet into your vagina once a day for the first two weeks of treatment. Then you do it twice a week until you no longer need it.
You use an applicator to get the cream into your vagina. You'll typically apply the cream daily for 1 to 2 weeks, then cut back to one to three times a week as directed by your doctor.
Antifungal medications are available as creams, ointments, tablets and suppositories. An antifungal regimen that lasts one, three or seven days will usually clear a yeast infection. A number of medications have been shown to be effective, including butoconazole (Gynazole-1), clotrimazole (Gyne-Lotrimin), miconazole (Monistat 3), and terconazole (Terazol 3). Some of these are available by prescription only, while others are available over-the-counter. Side effects might include slight burning or irritation during application. You may need to use an alternative form of birth control. Because the suppositories and creams are oil-based, they could potentially weaken latex condoms and diaphragms.

I hope this answers your query.
In case you have additional questions or doubts, you can forward them to me, and I shall be glad to help you out.

Wishing you good health.
Regards.
Dr. Rakhi Tayal

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