Virilization if you go overboard, and these are some of the major items of virilization:
Deepening voice (This is most often the first sign)
Growth of facial hair
Hair loss
enlarged Clitoris
Irregular menstrual cycles
breast shrinkage
acne
These can be considered sides as well, but depending on the person could be negative or positive:
Increased sex drive
Increased Clitoris sensitivity
Now with all that said, lots of women who have done their research have taken Anabolic steroids and avoided the major side effects. Most of the time they are taking Anavar and/or Primo and not things like Deca and Tren. Unless you are working with a script directly from your doctor that uses FDA approved pharmacy or a source you have bought from multiple times, I would test any Anavar before use. A test kit is available that will allow you to test it at home, just do some internet searching. (I would source, but I know the forum directly states sourcing Anabolic steroids or SARMS will get you banned and not sure if the same is true about other supplies. Rules are apparently different for moderators and such though.) As a female I wouldn't trust the word of any vender and test as taking the wrong thing can be extremely detrimental to a female compared to a guy. Also some venders significantly under dose what they sell to save money. If it doesn't take a doctors script you are getting it from an underground Lab and no regulation exists for your safety, so you have to be the regulator.
5 mg of Anavar taken twice a day seems to be the max recommended, but experienced users who are not experiencing any sides at this level have been known to slowly step up the daily dose safely. Under most cases though 10 mg will be more than enough to accomplish the goal of most women while also minimizing the possibility of any of the negative side affects.