How to handle toxic personalities in the workplace?

Finally, we’ll walk you through the key players who can support and manage these situations—because solutions do exist, and they matter.

1. What is a toxic personality at work?

Toxic personalities are individuals whose behaviour revolves exclusively around their own well-being, often at the expense of others. As social beings, we thrive on healthy relationships. Toxic individuals, however, create discomfort and imbalance through jealousy, criticism, guilt, or manipulation.

What one person perceives as toxic might seem harmless to another. Everything depends on personal values, past experiences, and reference points.

Take this example: a team member never says “hello” when arriving at the office. Some colleagues won’t mind. Others will take it as a personal slight. Same behaviour, different impact, because perception shapes reality.

In corporate environments, toxic personalities tend to fall into four categories:

• The Narcissistic Personality : Grandiosity, a constant need for admiration, and very little empathy for others.
• The Borderline Personality : Emotional instability, intense and conflictual relationships, and a deep fear of abandonment.
• The Antisocial Personality : Disregard for social norms, manipulation or exploitation of others, and an absence of remorse.
• The Paranoid Personality : Excessive suspicion, distrust, and the belief that others’ actions are intentionally harmful.

2. How toxic personalities operate

There are different levels of toxicity, understanding them is crucial.

1) Level 1: The unaware toxic personality. The person does not realise the negative impact of their behaviour.

2) Level 2: The personality acting out due to personal or professional suffering. Emotionally blocked, lacking emotional regulation tools, they express distress through inappropriate behaviour.

3) Level 3: Toxic behaviour driven by psychotic mechanisms

Triggered by a major life event (grief, separation, closure of a department…), these individuals develop fears that turn into maladaptive behaviours.
Unconscious psychological processes take over, often creating paranoia and deep dysfunctions.
These cases fall under first-level neuroses—serious, but not requiring institutionalisation.

Inside companies, most professionals are not trained to understand or manage such psychological complexity—neuroses, emotional storms, irrational fears… yet these dynamics shape everyday interactions.

3. What risks do toxic personalities create for companies and teams?

From declining productivity to resignations, from team tensions to a damaged employer brand—risks are everywhere.

The Narcissistic Personality

Seeks attention, exploits others, prioritises personal needs over team goals, refuses to acknowledge colleagues’ contributions.
Result: resentment, demotivation, and fractures within the team.

The Borderline Personality

Swings from enthusiasm to anger in minutes, creates conflictual relationships, reacts excessively to criticism.
Result: a stressful, destabilising working environment.

The Antisocial Personality

Breaks rules, manipulates colleagues, ignores the impact of actions on others.
Result: demoralised teams and potentially… legal issues.

The Paranoid Personality

Spreads suspicion, accuses colleagues without evidence, constantly on the defensive.
Result: collaboration collapses, trust disappears.

4. Who can effectively manage toxic personalities—and how?

Managing these situations is a collective responsibility. Several actors play key roles:

• The Manager : The first line of defence. They observe, identify patterns, intervene early, and set boundaries.
• Human Resources : Support the manager through training, tools, and direct intervention when necessary.
• Occupational Health Physician : Often the first to raise an alert.
• Specialised Consultants : Experts in psychosocial risk prevention or harassment prevention—mandatory for companies with 300+ employees.
• Coaches and Trainers : Help strengthen emotional intelligence, stress management, communication, and conflict navigation.
• Professional Mediators : Neutral facilitators who help restore dialogue and rebuild trust.

Expert insight: Jean-Marc Ségui, HR Creative, Coach & Mediator

We asked Jean-Marc a key question: When does coaching stop being enough, and when does mediation become the only viable solution?

Here is his expert view:

• 1. First question: Is the relationship toxic—or the person?

If the person behaves inappropriately repeatedly → coaching is relevant.
If the relationship itself becomes conflictual → mediation is the right tool.

• 2. When the person is both toxic and psychotic (paranoia, narcissistic perversion)

The only sustainable option is negotiating an exit… with the occupational physician.

The 4 warning signs that help identify toxic personalities

1. Inappropriate behaviours

Example: violating social norms (e.g., touching someone inappropriately).

2. Repetition

If behaviour is repeated → it's no longer an accident; it becomes dysfunction.

3. Collective impact

When toxicity affects team morale or performance → the situation is officially toxic.

4. Reaction to confrontation

Two types:

• The suffering collaborator → emotional distress, tears, remorse → can be supported.
• The narcissistic pervert (PN) → deflects responsibility, questions your competence, blames others → no accountability.

A typical PN line? “When you’re the oak surrounded by acorns, there’s only so much you can do.” Humour… with venom.

Did you know? Narcissistic perverts represent 3% of employees.

Coaching & mediation: not magic fixes, but pathways to resolution

Their role is to help teams “exit from above”—with dignity, clarity, and restored collaboration. Mediation can even support negotiated departures when the situation is beyond repair.

For further reading, Jean-Marc recommends: “Les personnalités difficiles ou dangereuses au travail” by Roland Guinchard.

In summary : Toxic personalities threaten the company’s social and economic fabric:

• declining service quality
• team departures
• damaged reputation
• internal conflicts

Prevention, training, and open conversations are essential. And sometimes, organising a seminar outside the office, in one of our 70 houses, creates the distance needed to rebuild clarity and connection.

If you’re facing a toxic collaborator or even a toxic collective, don’t hesitate to reach out to Jean-Marc Ségui. He offers a free initial diagnostic session, pro bono.