Rx abbreviations for pediatric prescriptions (reference)

Common prescription ("sig") abbreviations, plus safety reminders for ambiguous shorthand.

Last reviewed: February 12, 2026

⚠️

Medication safety disclaimer

Decision support only. Avoid error-prone abbreviations where possible and follow local prescribing policies.

Abbreviation list

Search common sig abbreviations and see safer wording when applicable.

Before meals

Example: Give ac meals

ad lib

As desired

Example: Feeds ad lib

BID

Twice daily

Example: Amoxicillin BID

cap

Capsule

Example: 1 cap daily

Gram

gtt

Drops

Example: 2 gtt in each eye

At bedtime

Example: Give HS

Intramuscular

Example: Ceftriaxone IM

INH

Inhalation

Example: Albuterol INH PRN

avoid

International units (avoid)

Can be misread as IV or 10. Write "international units".

Intravenous

Example: Ampicillin IV

Kilogram

Liter

mcg

Microgram

Milligram

mg/kg

Milligrams per kilogram

Example: Dose: 10 mg/kg per dose

mg/kg/day

Milligrams per kilogram per day

Example: 30 mg/kg/day divided BID

MgSO4

avoid

Magnesium sulfate (avoid)

Can be confused with morphine sulfate; write "magnesium sulfate".

Milliliter

avoid

Morphine sulfate or magnesium sulfate (avoid)

Ambiguous; write the full drug name.

MSO4

avoid

Morphine sulfate (avoid)

Can be confused with magnesium sulfate; write "morphine sulfate".

NPO

Nothing by mouth

Example: NPO prior to procedure

After meals

Example: Give pc meals

By mouth (oral)

Example: Take PO twice daily

Per rectum (rectal)

Example: Acetaminophen PR

PRN

As needed

Example: Ibuprofen PRN fever

q12h

Every 12 hours

Example: BID ≈ q12h

q24h

Every 24 hours

Example: Once daily ≈ q24h

q6h

Every 6 hours

Example: q6h PRN

q8h

Every 8 hours

Example: Antibiotic q8h

avoid

Daily (avoid)

Prefer writing "daily".

QID

Four times daily

Example: QID dosing

QOD

avoid

Every other day (avoid)

Prefer writing "every other day".

avoid

Subcutaneous (avoid)

Can be misread; write "subcutaneous".

Sublingual

Example: Dissolve SL

soln

Solution

Example: Oral soln

avoid

Subcutaneous (avoid)

Often recommended to avoid; write "subcutaneous".

STAT

Immediately

Example: STAT dose

supp

Suppository

Example: Rectal supp

susp

Suspension

Example: Oral susp

tab

Tablet

Example: 1 tab daily

TID

Three times daily

Example: Clindamycin TID

TOP

Topical

Example: Apply TOP to affected area

avoid

Units (avoid)

Can be misread as 0, 4, or cc. Write "units".

Abbrev	Meaning	Example / notes
ac	Before meals	Example: Give ac meals
ad lib	As desired	Example: Feeds ad lib
BID	Twice daily	Example: Amoxicillin BID
cap	Capsule	Example: 1 cap daily
g	Gram
gtt	Drops	Example: 2 gtt in each eye
HS	At bedtime	Example: Give HS
IM	Intramuscular	Example: Ceftriaxone IM
INH	Inhalation	Example: Albuterol INH PRN
IUavoid	International units (avoid)	Can be misread as IV or 10. Write "international units".
IV	Intravenous	Example: Ampicillin IV
kg	Kilogram
L	Liter
mcg	Microgram
mg	Milligram
mg/kg	Milligrams per kilogram	Example: Dose: 10 mg/kg per dose
mg/kg/day	Milligrams per kilogram per day	Example: 30 mg/kg/day divided BID
MgSO4avoid	Magnesium sulfate (avoid)	Can be confused with morphine sulfate; write "magnesium sulfate".
mL	Milliliter
MSavoid	Morphine sulfate or magnesium sulfate (avoid)	Ambiguous; write the full drug name.
MSO4avoid	Morphine sulfate (avoid)	Can be confused with magnesium sulfate; write "morphine sulfate".
NPO	Nothing by mouth	Example: NPO prior to procedure
pc	After meals	Example: Give pc meals
PO	By mouth (oral)	Example: Take PO twice daily
PR	Per rectum (rectal)	Example: Acetaminophen PR
PRN	As needed	Example: Ibuprofen PRN fever
q12h	Every 12 hours	Example: BID ≈ q12h
q24h	Every 24 hours	Example: Once daily ≈ q24h
q6h	Every 6 hours	Example: q6h PRN
q8h	Every 8 hours	Example: Antibiotic q8h
QDavoid	Daily (avoid)	Prefer writing "daily".
QID	Four times daily	Example: QID dosing
QODavoid	Every other day (avoid)	Prefer writing "every other day".
SCavoid	Subcutaneous (avoid)	Can be misread; write "subcutaneous".
SL	Sublingual	Example: Dissolve SL
soln	Solution	Example: Oral soln
SQavoid	Subcutaneous (avoid)	Often recommended to avoid; write "subcutaneous".
STAT	Immediately	Example: STAT dose
supp	Suppository	Example: Rectal supp
susp	Suspension	Example: Oral susp
tab	Tablet	Example: 1 tab daily
TID	Three times daily	Example: Clindamycin TID
TOP	Topical	Example: Apply TOP to affected area
Uavoid	Units (avoid)	Can be misread as 0, 4, or cc. Write "units".

High-risk abbreviations to avoid

U (units) — can be misread as 0, 4, or cc.
IU (international units) — can be misread as IV or 10.
QD / QOD — can be misread; prefer "daily" or "every other day".
Trailing zeros (e.g., 1.0 mg) — can be misread as 10 mg.
Lack of leading zero (e.g., .5 mg) — can be misread; prefer 0.5 mg.

Policies vary by institution—this list reflects common medication safety guidance.

Related tools

References

ISMP: Error-Prone Abbreviations, Symbols, and Dose Designations

Use local policy and clinical context. This page is a reference and does not replace pharmacy review.

Frequently asked questions

Some abbreviations are common, but certain shorthand can be error-prone. Many organizations recommend avoiding ambiguous abbreviations (for example "U", "IU", "QD", "QOD"). Follow your local policy and write directions clearly.

"Sig" refers to the patient directions ("signa") on a prescription—how to take the medication (dose, route, frequency, duration).

No. This is a reference page only. Medication safety requires full clinical context and pharmacy review when applicable.

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Rx abbreviations for pediatric prescriptions (reference)

Common prescription ("sig") abbreviations, plus safety reminders for ambiguous shorthand.

Last reviewed: February 12, 2026

⚠️

Medication safety disclaimer

Decision support only. Avoid error-prone abbreviations where possible and follow local prescribing policies.

Abbreviation list

Search common sig abbreviations and see safer wording when applicable.

Before meals

Example: Give ac meals

ad lib

As desired

Example: Feeds ad lib

BID

Twice daily

Example: Amoxicillin BID

cap

Capsule

Example: 1 cap daily

Gram

gtt

Drops

Example: 2 gtt in each eye

At bedtime

Example: Give HS

Intramuscular

Example: Ceftriaxone IM

INH

Inhalation

Example: Albuterol INH PRN

avoid

International units (avoid)

Can be misread as IV or 10. Write "international units".

Intravenous

Example: Ampicillin IV

Kilogram

Liter

mcg

Microgram

Milligram

mg/kg

Milligrams per kilogram

Example: Dose: 10 mg/kg per dose

mg/kg/day

Milligrams per kilogram per day

Example: 30 mg/kg/day divided BID

MgSO4

avoid

Magnesium sulfate (avoid)

Can be confused with morphine sulfate; write "magnesium sulfate".

Milliliter

avoid

Morphine sulfate or magnesium sulfate (avoid)

Ambiguous; write the full drug name.

MSO4

avoid

Morphine sulfate (avoid)

Can be confused with magnesium sulfate; write "morphine sulfate".

NPO

Nothing by mouth

Example: NPO prior to procedure

After meals

Example: Give pc meals

By mouth (oral)

Example: Take PO twice daily

Per rectum (rectal)

Example: Acetaminophen PR

PRN

As needed

Example: Ibuprofen PRN fever

q12h

Every 12 hours

Example: BID ≈ q12h

q24h

Every 24 hours

Example: Once daily ≈ q24h

q6h

Every 6 hours

Example: q6h PRN

q8h

Every 8 hours

Example: Antibiotic q8h

avoid

Daily (avoid)

Prefer writing "daily".

QID

Four times daily

Example: QID dosing

QOD

avoid

Every other day (avoid)

Prefer writing "every other day".

avoid

Subcutaneous (avoid)

Can be misread; write "subcutaneous".

Sublingual

Example: Dissolve SL

soln

Solution

Example: Oral soln

avoid

Subcutaneous (avoid)

Often recommended to avoid; write "subcutaneous".

STAT

Immediately

Example: STAT dose

supp

Suppository

Example: Rectal supp

susp

Suspension

Example: Oral susp

tab

Tablet

Example: 1 tab daily

TID

Three times daily

Example: Clindamycin TID

TOP

Topical

Example: Apply TOP to affected area

avoid

Units (avoid)

Can be misread as 0, 4, or cc. Write "units".

Abbrev	Meaning	Example / notes
ac	Before meals	Example: Give ac meals
ad lib	As desired	Example: Feeds ad lib
BID	Twice daily	Example: Amoxicillin BID
cap	Capsule	Example: 1 cap daily
g	Gram
gtt	Drops	Example: 2 gtt in each eye
HS	At bedtime	Example: Give HS
IM	Intramuscular	Example: Ceftriaxone IM
INH	Inhalation	Example: Albuterol INH PRN
IUavoid	International units (avoid)	Can be misread as IV or 10. Write "international units".
IV	Intravenous	Example: Ampicillin IV
kg	Kilogram
L	Liter
mcg	Microgram
mg	Milligram
mg/kg	Milligrams per kilogram	Example: Dose: 10 mg/kg per dose
mg/kg/day	Milligrams per kilogram per day	Example: 30 mg/kg/day divided BID
MgSO4avoid	Magnesium sulfate (avoid)	Can be confused with morphine sulfate; write "magnesium sulfate".
mL	Milliliter
MSavoid	Morphine sulfate or magnesium sulfate (avoid)	Ambiguous; write the full drug name.
MSO4avoid	Morphine sulfate (avoid)	Can be confused with magnesium sulfate; write "morphine sulfate".
NPO	Nothing by mouth	Example: NPO prior to procedure
pc	After meals	Example: Give pc meals
PO	By mouth (oral)	Example: Take PO twice daily
PR	Per rectum (rectal)	Example: Acetaminophen PR
PRN	As needed	Example: Ibuprofen PRN fever
q12h	Every 12 hours	Example: BID ≈ q12h
q24h	Every 24 hours	Example: Once daily ≈ q24h
q6h	Every 6 hours	Example: q6h PRN
q8h	Every 8 hours	Example: Antibiotic q8h
QDavoid	Daily (avoid)	Prefer writing "daily".
QID	Four times daily	Example: QID dosing
QODavoid	Every other day (avoid)	Prefer writing "every other day".
SCavoid	Subcutaneous (avoid)	Can be misread; write "subcutaneous".
SL	Sublingual	Example: Dissolve SL
soln	Solution	Example: Oral soln
SQavoid	Subcutaneous (avoid)	Often recommended to avoid; write "subcutaneous".
STAT	Immediately	Example: STAT dose
supp	Suppository	Example: Rectal supp
susp	Suspension	Example: Oral susp
tab	Tablet	Example: 1 tab daily
TID	Three times daily	Example: Clindamycin TID
TOP	Topical	Example: Apply TOP to affected area
Uavoid	Units (avoid)	Can be misread as 0, 4, or cc. Write "units".

High-risk abbreviations to avoid

U (units) — can be misread as 0, 4, or cc.
IU (international units) — can be misread as IV or 10.
QD / QOD — can be misread; prefer "daily" or "every other day".
Trailing zeros (e.g., 1.0 mg) — can be misread as 10 mg.
Lack of leading zero (e.g., .5 mg) — can be misread; prefer 0.5 mg.

Policies vary by institution—this list reflects common medication safety guidance.

Related tools

References

ISMP: Error-Prone Abbreviations, Symbols, and Dose Designations

Use local policy and clinical context. This page is a reference and does not replace pharmacy review.

Frequently asked questions

"Sig" refers to the patient directions ("signa") on a prescription—how to take the medication (dose, route, frequency, duration).

No. This is a reference page only. Medication safety requires full clinical context and pharmacy review when applicable.

Rx abbreviations for pediatric prescriptions (reference)

Medication safety disclaimer

Abbreviation list

High-risk abbreviations to avoid

Related tools

References

Frequently asked questions

Are Rx abbreviations safe to use?

What does "sig" mean?

Does this page replace pharmacy review?

Rx abbreviations for pediatric prescriptions (reference)

Medication safety disclaimer

Abbreviation list

High-risk abbreviations to avoid

Related tools

References

Frequently asked questions

Are Rx abbreviations safe to use?

What does "sig" mean?

Does this page replace pharmacy review?