About plants like dandelion and artichoke causing photoallergic reactions, does it occur after the juices get onto your skin, or after you eat them?

Photosensitive plant: Photosensitivity can also result from touching or eating other plants, including celery, dill, fennel, fig, lime, parsley, and parsnip, as well as arnica, artichoke, chrysanthemum, dandelion, lettuce, endive, marigold, and sunflower.4, 5 lest you swear off gardening or salads altogether, be aware that most people do not react to these plants. Essential oils of plants may be more problematic