Definition

1. Noun:
   • An unintended and typically undesirable secondary result of an action or situation. This meaning applies broadly to any planned intervention, policy, or event, where an unforeseen negative consequence occurs alongside the intended outcome.
   • An unwanted secondary reaction to a medication or medical treatment. This is the most common specific usage, referring to a symptom or condition caused by a drug or therapy, distinct from its intended therapeutic effect.

Usage Examples

• Noun (General Unintended Consequence):
  • A significant side effect of the new traffic system has been increased congestion on side streets.
  • The economic policy succeeded in reducing inflation, but unemployment was a painful side effect.
• Noun (Medical Context):
  • Drowsiness is a common side effect of this allergy medication.
  • The doctor explained the potential side effects of the chemotherapy before starting treatment.

Advanced Usage

• "To have side effects": This is the standard collocation for experiencing unwanted reactions, especially from medication.
  • Some patients have no side effects at all.
• "A side effect of (doing something)": Used to link the unintended consequence to a specific cause.
  • One side effect of working from home can be feeling isolated.

Variants and Related Words

• Side-effect (noun): A less common hyphenated spelling variant.
• Adverse effect (noun): A more formal term, often used interchangeably in medical and technical contexts, emphasizing harm.
• Unintended consequence (noun phrase): A broader, more general synonym for the first definition.

Synonyms

• Consequence (especially )
• Reaction (in medical context)
• By-product (often for non-medical contexts)
• Fallout (metaphorical, for negative consequences of an event)

Related Phrases

• To minimize side effects: To reduce the risk or severity of unwanted effects.
  • The medication should be taken with food to minimize side effects.
• To list/describe the side effects: To detail the possible unwanted reactions.
  • The pamphlet lists the side effects in order of frequency.

Noun

1. any adverse and unwanted secondary effect
   • a strategy to contain the fallout from the accounting scandal
2. a secondary and usually adverse effect of a drug or therapy
   • severe headaches are one of the side effects of the drug