flare up
(a problem, illness, or conflict) suddenly start again or get worse
What does "flare up" mean?
Examples
- Violence flared up again in the border region after weeks of relative calm.
- Her eczema has flared up badly this week — she thinks it might be a reaction to the new soap.
- Tempers flared up during the meeting when the manager announced the redundancies.
How to use it
The core intransitive pattern — the conflict, condition, or problem is always the subject, and no object follows the verb.
Tensions along the border flared up overnight, catching diplomats by surprise.
Adding 'again' reinforces the sense of recurrence — that this is not the first time the problem has occurred.
His asthma has flared up again, probably because of the cold, dry air.
A time clause introduced by 'after' or 'when' is commonly used to specify what triggered the sudden worsening.
The dispute flared up again after one party withdrew from the peace talks.
The present perfect is particularly common in medical and news contexts to describe a recent resurgence with present relevance.
Violence has flared up in several districts following the announcement of the election results.
Adverbs of degree or time can follow the verb directly to emphasise the speed or severity of the resurgence.
Her arthritis flared up badly during the cold snap last month.
Common Collocations
Common Mistakes
'Flare up' is strictly intransitive — it never takes a direct object. The conflict or illness itself is always the subject, and nothing follows the verb as an object.
Use 'break out' when something is happening for the very first time — a new conflict starting, a fresh outbreak of disease. Use 'flare up' only when something that already existed or had previously occurred suddenly worsens again.
In this sense, only a problem, conflict, illness, or emotion can flare up — not a person. Using a person as the subject shifts the meaning to a different sense (someone reacting angrily), which is a separate entry.
Usage
This phrasal verb is neutral and works in both formal writing (e.g. news articles about political unrest) and everyday conversation (e.g. talking about a recurring health condition). It always implies that something got suddenly worse, often after a period of calm, and frequently suggests the problem has happened before.
Frequently Asked Questions
Can 'flare up' be used in the passive, like 'the situation was flared up by the announcement'?
No — 'flare up' is intransitive, meaning it never takes an object, so a passive construction is not possible. The situation, condition, or conflict is always the subject that performs the action: 'the situation flared up after the announcement'.
Does 'flare up' always suggest the problem happened before?
Yes, this is a key part of the meaning. 'Flare up' implies that the situation or condition already existed and has suddenly worsened or returned — it is not used for something starting from zero. If you want to describe something beginning for the first time, 'break out' is the better choice.
What kinds of subjects can you use with 'flare up' in this sense?
The subject is almost always either a conflict or crisis (violence, tensions, fighting, a dispute), a chronic medical condition (eczema, asthma, arthritis, an old injury), or an emotion in a group or situation (tempers, anger). The subject is always the problem itself — never a person who is deliberately doing something.
Is 'flare up' only used in formal contexts like news articles?
Not at all — it works equally well in informal conversation, for example when talking about a recurring health condition or a recurring disagreement. You might hear it in a doctor's appointment, a casual chat with a friend, or a news broadcast. It has no strong formal or informal restriction.
Can I use 'flare up' to describe a gradual worsening over time?
No — the suddenness of the resurgence is central to the meaning. If something is worsening slowly and steadily, a phrase like 'escalate' or 'heat up' would be more accurate. 'Flare up' always implies an abrupt and often unexpected surge in intensity.
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