An evaluation of black tongue begins with a history and physical examination.

Physical findings in someone with black tongue include:

• Black tongue

Additional physical findings in someone with black tongue may include:

• A reddened tongue
• Tongue ulcers
• White patches on the tongue
• Hairy tongue

Tests may be required to exclude other conditions, which can cause similar symptoms.

Tests that may be used to evaluate black tongue include:

• Complete blood count
• VDRL (test for syphilis)
• Serum vitamin B12 level
• Serum folate level
• Serum glucose testing
• Bacterial or fungal cultures from tongue scrapings
• Strep screen