Allergies

I put together a glycerite of Nettle Leaf and Mullein for allergy relief. My son said it helped relieve his symptoms and thinks it will work well for him. My co-worker however experienced swelling in her leg and foot after taking only 2 droppers (separate times). She noticed the swelling later that evening. She doesn't know if this is from the glycerite or just a coincidence because she has had swelling before, but it's been a long time ago. She wants to try the extract again to see if it happens again, but I advised her not to. Any suggestions? (btw, she is on high BP medication).