S90.42 – Blister (nonthermal) of toe

ICD-10-CM 2027 diagnosis code · Injuries to the ankle and foot

Non-billable header

ICD-10-CM code S90.42

Code: S90.42 (claims format: S9042)
Description: Blister (nonthermal) of toe
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 19. Injury, poisoning and certain other consequences of external causes (S00-T88)
Block: S90-S99 Injuries to the ankle and foot
Parent codes: S90 › S90.4

Billable codes under S90.42

S90.42 is a header code and cannot be used on claims. Choose the most specific code:

S90.421 – Blister (nonthermal), right great toeHeader (more codes below)
S90.422 – Blister (nonthermal), left great toeHeader (more codes below)
S90.423 – Blister (nonthermal), unspecified great toeHeader (more codes below)
S90.424 – Blister (nonthermal), right lesser toe(s)Header (more codes below)
S90.425 – Blister (nonthermal), left lesser toe(s)Header (more codes below)
S90.426 – Blister (nonthermal), unspecified lesser toe(s)Header (more codes below)

7th character values

Codes in this category need a 7th character to describe the encounter or episode of care (use placeholder X for empty positions).

Character	Meaning
`A`	initial encounter
`D`	subsequent encounter
`S`	sequela

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

S90 – Superficial injury of ankle, foot and toes

7th character note:

The appropriate 7th character is to be added to each code from category S90

Block S90-S99

Excludes2 (not included here):

burns and corrosions (T20-T32)
fracture of ankle and malleolus (S82.-)
frostbite (T33-T34)
insect bite or sting, venomous (T63.4)

Index terms for S90.42

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in S90.4

S90.41 – Abrasion of toeHeader
S90.44 – External constriction of toeHeader
S90.45 – Superficial foreign body of toeHeader
S90.46 – Insect bite (nonvenomous) of toeHeader
S90.47 – Other superficial bite of toeHeader

Frequently asked questions

What is ICD-10 code S90.42?

S90.42 is the ICD-10-CM code for blister (nonthermal) of toe, in the block S90-S99 (Injuries to the ankle and foot).

Is S90.42 a billable code?

No. S90.42 is a header code with more specific child codes; report one of the billable codes listed above.

What category does S90.42 belong to?

It belongs to category S90 – Superficial injury of ankle, foot and toes.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.