Anyone with a persistent tongue rash or other tongue problem that doesn't go away should seek medical care, according to MedlinePlus. If the tongue starts to swell and causes difficulty breathing, it is necessary to seek emergency medical help immediately.
The tongue changes color, develops bumps or rashes, or otherwise changes in appearance for many reasons that are not medical emergencies. Injury, inflammation and heavy smoking all change the appearance of the tongue, as do canker sores, which typically heal on their own. Hairy tongue and black tongue are other benign conditions that sometimes develop and are typically helped by good oral hygiene, as MedlinePlus explains.