The workplace offers a multitude of opportunities for stress and pressure, including clashes with colleagues. When personal animosity from a co-worker greets you every morning, your workday can become a nightmare. No one should have the power to ruin your day. If you can’t avoid the toxic co-worker, learn how to cope.

Assess the problem. Does the difficult co-worker hate you specifically, or is she generally antagonistic to everyone? If you seem to be the sole target, find out why. Don’t let the situation drag on. Act quickly to deal with it before it gets worse. Don’t resort to angry emails or gossiping about your nemesis. Don’t confront her in front of others.

Meet privately with the co-worker. Rehearse beforehand what you are going to say and how you will respond to her. Let her know that you see what is going on, that you need to know what is causing the problem, and that you won’t allow it to continue. She may deny any personal animosity toward you. Point out specific circumstances when she has publicly belittled you, taken credit for your work, badmouthed you to others, or behaved unprofessionally in other ways.

Say you are sorry if your co-worker claims you have hurt her. You may not realize that she has been harboring a grudge over some perceived slight. Perhaps you received a promotion that she wanted. She may feel threatened by you and your abilities. Perhaps you just remind her of someone else she dislikes. Don’t get drawn into an argument about “who started it.” Be confident but not arrogant. Just listen to her and stay calm and professional. She may have personal problems that have nothing to do with you.

Fight anger with kindness. If a difficult co-worker is trying to provoke you into a verbal duel, respond instead with kind words and helpful actions. Avoid telling her that you were hurt by her behavior, which might be just what she wants. Instead, focus on how her actions hamper your productivity as well as her own. Remind her that you have to work together and that a negative environment is detrimental to you both and to your employer.

Ask for help. Adversarial relationships in the workplace can poison the atmosphere for everyone, so seek help from your supervisor or manager. Chances are he may have already noticed the problem. If your company has a human resources department, handling office discord is part of the job. Note specific examples of the conflict, and describe your efforts to deal with it. Rather than complaining that you are hurt, explain how the conflict is affecting the business and your job performance.

Walk away. If the toxic situation is affecting your work and your morale, and none of your efforts to solve the problem have helped, you may have to request a transfer to another department or leave the job altogether.