Pay attention to physical fear or emotional reactions from those around him, and less attention to evidence that is inconsistent with his or her negative predictions. However, these reactions should not be interpreted as a child's personality weakness or inability to adapt, but should be understood in the context of the psychological strain caused by the illness and his developmental limitations. The stage of cognitive development plays an important role in shaping a child's perception of the effects of chemotherapy. Young children usually process information objectively and limited to close experiences, and may make a simple but inaccurate connection between illness, medication, pain, and body changes. Some may see changes in appearance as a sign of loss of identity or love, while school-age children are more concerned about daily functioning, class attendance, and the reaction of friends. Adolescents may also have more complex concerns about body image, independence, privacy, emotional relationships, and the future of education. Therefore, the content of fear varies at different ages, and psychological interventions should be tailored based on the child's level of development, individual experiences, and type of concern. From an emotional perspective, fear of treatment complications can be accompanied by anxiety, sadness, anger, helplessness, shame, and feelings of insecurity. Some children express their concern in the form of frequent questions about medications or complications, while others avoid talking about the disease or react by crying, irritability, and clinging to parents. Emotional reactions may increase on the eve of chemotherapy sessions and intensify as they approach time to receive medication, observe medical equipment, or recall previous unpleasant experiences. This pattern is related to the concept of anticipatory anxiety, a condition in which the expectation of an unpleasant event before it happens causes mental and physical arousal. In some children, this arousal is accompanied by heart palpitations, sweating, muscle tension, stomach pain, restlessness, or sleep disturbances. Such symptoms, in turn, can be interpreted as evidence of an imminent danger, exacerbating fear. As a result, a cycle is formed in which negative anticipation, physical anxiety, greater attention to symptoms, and increased sense of threat reinforce each other. Of course, every physical symptom in children with cancer should not be attributed to anxiety, as drug complications, physical changes, and medical problems may also cause similar symptoms, and proper clinical evaluation is necessary. Behavioral mechanisms also play a role in maintaining or reducing fear of chemotherapy complications. One common reaction is to avoid treatment-related stimuli; the child may refuse to enter the hospital, see the equipment, discuss complications, or ask questions to the doctor. Avoidance can create a sense of calm in the short term, but if it becomes the dominant coping pattern, it reduces the opportunity to gain accurate information and experience successfully managing worry. Some children also ask repetitive questions or constantly ask parents to ensure that no complications will occur. Supportive responses can help a child calm down, but unrealistic reassurance and a firm promise that there will be no complications may undermine their confidence. The appropriate approach is to accept the child's feelings, provide him with real and understandable information, and teach him strategies to deal with possible situations. In this framework, the psycho-oncologist can help identify the perpetuating cycles of distress by assessing the thoughts, emotions, and behaviors related to fear, and design a program tailored to the needs of the child and the family. One of the important interventions is age-appropriate psychological education. The child should know that chemotherapy is aimed at treating the disease, possible complications vary from person to person, and the treatment team works to prevent, identify, and manage many problems. The information should be provided honestly, staged, and proportionate to the child's level of readiness. Explaining too much and without regard to the child's emotional capacity may increase fear, while complete secrecy can also create feelings of mistrust and confusion. It is best to ask the child what he or she knows about the treatment, what they are most afraid of, and what information they need to feel safer. The information can then be broken down into small chunks, providing ample opportunity to question, recount, and correct misconceptions. Cognitive-behavioral interventions can also be effective in reducing catastrophic thoughts and strengthening coping skills. In this approach, the therapist helps the child understand the difference between the probability of a complication occurring and the certainty of its occurrence, examine exaggerated perceptions, and develop a practical plan to deal with real concerns. The goal is not to convince the child that no complications will occur, but to increase their ability to tolerate uncertainty and recognize ways to get help. Teaching slow breathing, muscle relaxation, mental imagery, and targeted distractions can also be used in managing anxiety before treatment. These techniques are most useful when practiced in calm situations and the child can use them when anxiety increases. Play therapy and art therapy also provide opportunities to indirectly express fears and process complex experiences of illness. Painting about concerns, storytelling, using dolls, and role-playing therapeutic situations can help the child to ask questions and represent difficult emotions in a supportive environment. In these activities, attention should be paid to the meaning that the child expresses for his or her experience, and one should not draw definitive conclusions about his or her mental state from a single drawing or behavior. Family support is also important in managing fear. Parents are usually the child's first reference point for information and a sense of security, and their reactions may affect the child's assessment of the level of danger. When parents respond with intense concern, prolonged silence, or conflicting information, the child may perceive the situation as more threatening; in contrast, calm communication, age-appropriate honesty, and acceptance of the child's feelings can help reduce confusion. This does not mean holding parents accountable for the child's fears, as they are also in a difficult state of illness and may need professional support. A psycho-oncologist can strengthen the family's capacity to accompany the child by teaching communication skills, coping strategies, and emotional support techniques. Coordination between parents, doctors, nurses, and mental health professionals is also important, as providing conflicting messages about complications or stages of treatment may increase anxiety. Actual management of physical complications should be placed alongside psychological interventions. Proper handling of nausea, pain, sleep disturbances, fatigue, and other treatment-related problems can prevent exacerbations of anxiety and show the child that their complaints are being taken seriously. If fear leads to refusal of treatment, severe dysfunction, frequent anxiety attacks, or a significant decrease in quality of life, a more detailed professional evaluation is necessary. In such a situation, the severity and persistence of symptoms, psychological history, family conditions, and the possibility of concurrent problems should be assessed, and if necessary, specialized interventions or referrals to a child psychiatrist should be performed. Research evidence in the field of pediatric cancer psychology supports the importance of age-appropriate education, empathetic therapeutic communication, family support, and cognitive-behavioral interventions in the management of treatment-related distress, however, children's responses to these methods are not uniform and their effectiveness depends on the type of concern, distress severity, clinical conditions, and quality of intervention implementation. One of the important limitations in investigating fear of chemotherapy complications is the difficulty of separating normal concern from significant clinical distress. Also, physical changes caused by treatment can affect a child's mood, behavior, and concentration, making it difficult to detect the exact origin of each symptom. Differences in age, type of cancer, medication regimen, previous experiences, and family support also limit the comparison of research findings. Therefore, the evaluation should be continuous, person-centered, and based on a combination of child reporting, clinical observation, and family information. It is suggested that pediatric oncology centers include fear of treatment complications in the routine evaluation of psychological distress and identify the main concerns of each child before starting chemotherapy. Supportive programs should be designed based on developmental needs, treatment history, preference of the child, and the extent of dysfunction, and should be reviewed during treatment according to changes in physical and emotional conditions. Educating health care workers on how to inform, answer difficult questions, and identify symptoms of anxiety can also improve the quality of communication and treatment experience. In addition to measuring the severity of fear, future research should investigate its relationship with adherence to treatment, quality of life, avoidance behaviors, and long-term adaptation, and evaluate the effectiveness of combined interventions in different age groups. In general, fear of chemotherapy complications in children is the result of a complex interaction of cognitive, emotional, and behavioral processes and cannot be attributed solely to a lack of information or individual sensitivity. Understanding this fear requires paying attention to the child's lived experience, the meaning it gives to physical changes, and the degree of control he feels in the therapeutic situation. The role of the psycho-oncologist in this path is to identify threatening perceptions, strengthen coping skills, support the family, and coordinate with the treatment team to provide integrated care. The ultimate goal is for the child to be able to understand possible complications, express their concerns, and go through the chemotherapy path with a greater sense of security and empowerment without denying the realities of treatment.