Hmmm…interesting question.
Most studies suggest that gingko may improve hair health rather than bothering it (though those studies are few and far between).
That said, there are some studies that have suggested that Ginkgo biloba extracts may inhibit the activity of thyroid peroxidase, an enzyme involved in the production of thyroid hormones. I suppose this inhibition could theoretically lead to reduced thyroid hormone synthesis.
I don’t think the inhibition would be significant at all in a person with normal thyroid function but if a person’s thyroid function was a bit on the weak side, it might be enough to lower levels enough to start seeing low thyroid symptoms (like hair loss).
Mostly, we each need to become an expert on our own body. If our body doesn’t get long well with aparticular herb or food etc… we should probably listen to it.
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.