I would have to say any dangers with long term usage would definitely have to do with dosage with all of those...but you shouldn't need parasite and yeast protection constantly, you want to strengthen your immune system so it can take care of itself eventually.

I wouldn't take olive leaf unless I was sick or when I really needed it. Its a wide spectrum anti-biotic that will kill good bacteria as well...and good bacteria are essential in building a healthy immune system.

Garlic is great if you tolerate it, so you could definitely at least eat a little more of raw garlic long term and see how that works.