adverse effect; adverse drug reaction
Pharmacological term for harmful or unintended effects of a drug or treatment. Often abbreviated as ADR in medical contexts.
Adverse effects of this medication include nausea and dizziness.
有害作用が報告された場合、直ちに医師に連絡してください。
If an adverse reaction is reported, contact a doctor immediately.
副作用 is the common term for side effects, including both harmful and non-harmful ones. 有害作用 specifically emphasizes harmful or toxic effects, often in a pharmacological or clinical context.
Compound of 有害 (harmful) and 作用 (action, effect). The term is a direct translation of the English 'adverse effect' and is used primarily in medical and pharmacological fields.