Certified GKH Gardening Expert
Hibiscus flowers are not thought to cause allergy problems, but if the plant has a fungus or a bug infestation, this could trigger allergy problem. I would check the plant over carefully, particularly where the stems meet. Look for cottony, scale like or powdery residue. This will be small pests and can be treated with any standard insecticide. If the leaves have a powdery covering or have brown spots, this is a fungus and the plant can be treated with a fungicide.