Is it possible for consuming raw garlic to worsen/agravate lichen planus?

Not possible: exact cause is unknown for lichen planus but emotional stress is usually involved. symptomatic treatment or none at all is the case. garlic has no effect i know of.

On the contrary : The latest study shows that garlic has the active ingredient of Allium sativum. and significantly efficient in the management of oral lichen planus (a chronic inflammatory disease that causes bilateral white striations on the buccal mucosa). The major side effect is your wife and family might complain that your breath and body smells like garlic.