S00.521A Blister (nonthermal) of lip, initial encounter

Billable ICD-10-CM code, FY2026.

Built from S00.521 with 7th character A (initial encounter).

Applies from S00 Superficial injury of head

Excludes1 (never code together)

• diffuse cerebral contusion (S06.2-)
• focal cerebral contusion (S06.3-)
• injury of eye and orbit (S05.-)
• open wound of head (S01.-)

7th character note

• The appropriate 7th character is to be added to each code from category S00

7th character required

• A — initial encounter
• D — subsequent encounter
• S — sequela

Code annotations containing back-references to S00.521A

Back-references to S00

• Code Also: G96.00 Cerebrospinal fluid leak, unspecified ("head injury (S00-S09)")
• Code Also: G96.08 Other cranial cerebrospinal fluid leak ("head injury (S00 - S09)")
• Code Also: G96.09 Other spinal cerebrospinal fluid leak ("head injury (S00 - S09)")
• Code First: R65.1 Systemic inflammatory response syndrome (SIRS) of non-infectious origin ("injury and trauma (S00-T88)")

Diagnosis Index entries for S00.521A

• Blister (nonthermal) › head › lip
• Blister (nonthermal) › lip

Nearby codes

• S00.512A Abrasion of oral cavity, initial encounter
• S00.512D Abrasion of oral cavity, subsequent encounter
• S00.512S Abrasion of oral cavity, sequela
• S00.52 Blister (nonthermal) of lip and oral cavity
• S00.521 Blister (nonthermal) of lip
• S00.521A Blister (nonthermal) of lip, initial encounter (this code)
• S00.521D Blister (nonthermal) of lip, subsequent encounter
• S00.521S Blister (nonthermal) of lip, sequela
• S00.522 Blister (nonthermal) of oral cavity
• S00.522A Blister (nonthermal) of oral cavity, initial encounter
• S00.522D Blister (nonthermal) of oral cavity, subsequent encounter