Fasting quick reference - healthy elective patients

These are guideline comparisons for appropriate elective patients, not a universal fasting prescription. Application depends on aspiration-risk assessment and the applicable institutional policy.

Adults

Clear liquids. ASA and ISA guidance commonly uses a minimum 2-hour interval in healthy elective adults. ASA 2023 includes carbohydrate-containing clear liquids. A shorter interval belongs within an applicable institutional protocol, rather than an instruction extrapolated from this summary.

Light meal / non-human milk. ASA 2017: 6 h. The amount and type of intake matter. ISA 2020: light meal 6 h. It separately classifies non-clear liquids at 4 h.

Fried/fatty food or meat. ASA 2017: additional fasting time, e.g. 8 h or more. ISA 2020: for a heavy meal, it is prudent to wait at least 10 h.

Chewing gum. ASA 2023 suggests not delaying elective procedures in healthy adults who have chewed gum, after confirming the gum has been removed before induction. The 2023 update also reaffirms the 2 h clear-liquid interval and notes that carbohydrate-containing clear liquids reduce hunger compared with non-caloric clear liquids. Adding protein showed no clear benefit or harm.

Children

Clear liquids. ASA 2023 found insufficient evidence to recommend 1 h rather than 2 h universally. The guideline encourages clear liquids as close to 2 h as possible in low-risk children. ISA 2020: water up to 3 mL/kg until 1 h, and other clear liquids up to 3 mL/kg until 2 h.

Breast milk and infant formula. ASA 2017: breast milk 4 h and infant formula 6 h. ASA 2023 did not address gum or protein-containing drinks in children. Institutional paediatric protocols may differ, particularly for neonates and infants.

Newer adult consensus

The 2026 international multidisciplinary adult consensus supports clear liquids until 2 hours before anaesthesia or sedation and allows more liberal intake within institutional protocols. Its definition permits a small milk addition to tea or coffee, up to one-fifth of the drink’s volume. It recommends at least 6 hours for solids and non-clear liquids, with 8 hours or longer potentially needed after large, fatty meals. It also permits salivation stimulants such as chewing gum or lollipops until transfer for the procedure, and favours resuming oral intake as soon as clinically feasible. These are adult elective recommendations; substantially increased aspiration risk and procedure-specific requirements need individual assessment.

Patients outside these references

These intervals apply to healthy elective patients. Individual assessment is needed in, for example:

Emergency surgery or bowel obstruction
Pregnancy, especially in later gestation or labour
Gastroparesis, significant reflux or swallowing disorders
Previous upper gastrointestinal surgery
Opioid therapy
GLP-1-based therapy (see the GLP-1 reference)
Diabetes, where carbohydrate drinks may need to be avoided or modified

Point-of-care gastric ultrasound, where expertise exists, may help assess gastric content when the fasting status or aspiration risk is uncertain.

Prolonged fasting

Actual fasting times frequently exceed guideline minimums because of list changes and delays. Institutional strategies such as time-specific instructions and permitting clear fluids until a defined point on the day can reduce unnecessary fasting.