Definition

Adverb 1. According to need; when necessary; as the situation demands: This phrase indicates that an action should be performed only when a specific condition or requirement arises, not on a fixed schedule. It is synonymous with "as needed" or "on demand."

Usage

The phrase "as required" is used to give flexible, conditional instructions. It is common in formal, technical, and procedural contexts such as medicine, engineering, manuals, and project management. It modifies verbs to show that the action's timing is dependent on a variable need.

Examples

• The medication should be taken as required for pain relief, but not more than four times a day.
• Additional staff will be deployed to the event as required to manage the crowd.
• Please review and update these documents as required by the new regulations.
• The system can allocate more memory as required to handle complex tasks.

Advanced Usage

• In Prescriptions (Medical Context): Often abbreviated as "PRN" (from the Latin , meaning "for an occasion as it arises"). This is a direct equivalent to "as required."
  • The prescription read: "Take one tablet PRN for anxiety."
• In Formal Procedures and Contracts: Used to specify conditional obligations or actions.
  • The contractor shall provide progress reports weekly, and detailed financial statements as required.

Variants and Related Words

• As needed (adv.): An exact synonym, often used interchangeably.
• On demand (adv.): Suggests immediate availability or action upon request.
• If necessary (adv. phrase): Indicates a conditional action based on need.
• PRN (adv.): A specialized medical abbreviation for "as required."

Synonyms

• As needed
• When necessary
• On a need-to basis
• According to need

Related Phrases

• As and when required: A more emphatic or formal variant with the same meaning.
  • Maintenance is performed as and when required to ensure safety.
• On an as-required basis: A longer form used to describe a mode of operation.
  • She works for the company on an as-required basis.

Adverb

1. according to need (physicians use PRN in writing prescriptions)
   • add water as needed