It will always depend on the amount of exposure, the body's detoxification ability of specific substances, and how the body reacts to substances. Some people can higher levels of exposure to substances and have very little or no reactivity, and others can have very little exposure and have severe reactivity.
For addressing systemic fungal problems, I recommend the McCombs Plan. There are many natural substances that can be of assistance for topical problems - Candida Force, coconut oil, lavender oil, oregano oil, etc. You may find that different mixtures have an impact that is better than one alone. Almost every plant and animal produces some type of antifungal substance to address fungus.