頓服

1. Origins, structure, and basic meaning

• Structure: 頓服, read とんぷく, is an as-needed medication or an instruction to take a single dose when symptoms require it.
• Basic usage: 時だけ飲む頓服 refers to the prescribed medicine; printed 頓服 gives the dosing instruction.

2. Common pitfalls and similar expressions

• Medication and as-needed instruction
  • The first context names the drug, while the packet label names how to take it; neither implies routine scheduled dosing.