As the Catechism of the Catholic Church asserts, “life and physical health are precious gifts entrusted to us by God. We must take reasonable care of them, taking into account the needs of others and the common good” (2288).
For Catholics, gratitude for life and a desire to treasure it should shape decisions about medical treatment. But any person facing illness, together with his or her family, caregivers and medical professionals, must determine what it means to take reasonable care of the gift of life in his or her situation. Sometimes proactive treatment is appropriate and sometimes it is not; sometimes medication is appropriate and sometimes it is not. A wide range of treatment options are possible depending on the person and the situation. Talk carefully with your doctor about the pros and cons of medication. Ask for support from family and friends. And pray deeply for guidance. Only you can discern what course of treatment best helps you to care for your life, the one very precious life that God has entrusted to you.
I would add that most mental health professionals would not prescribe medications if it were not a serious situation. Therefore careful judgement about your behavior should be paramount. For some, psychosis is the result of a chemical imbalance and medication is required for correction in many cases. In some cases, talk therapy or group therapy is all that is needed. Regardless, some treatment is probably in your future and to be mentally healthy you will need to cooperate with some regimen.