Common dandelion is native to moist riverbanks and grasslands of Europe. It has been spread to much of the temperate zones of the rest of the world. It is considered a weed in parts of America, and invasive on some French subarctic islands.

Common dandelions cause allergic reactions, including respiratory issues and anaphylactic shock. They interact negatively with medications like insulin and diuretics. Common dandelions absorb heavy metals from polluted soil, leading to potential heavy metal poisoning. Symptoms include nausea, vomiting, and weakness. Monitor small children around common dandelions and watch for symptoms if ingested. Avoid ingestion of contaminated plants. Keep an eye on children.

Common dandelion is thought to originate from Greece or even the Himalayas. The efficient spread via seeds and transportation, plus human uses and cultivation, means that it has become globally distributed – from the subtropics to the tundra. Common dandelion has a flowerhead with numerous small florets and each floret produces a seed. The seeds can fly or get carried far and wide because of their parachute-like fluff called pappus. Also, common dandelion quickly regenerates from any part of its long root left in the ground. Because it prefers compact and disturbed soils, common dandelion is most commonly a weed of cultivated fields and lawns.

The best time to remove or restrict common dandelion is in the early spring when the plants are young and haven't yet flowered, to prevent seed dispersal.