More recent studies show that around 50% of people who participate in conversion therapy had harmful effects, including severe depression and suicidality. Also, about 50% of people self-reported harmful effects of conversion therapy, including self-reports of anger, anxiety, confusion, depression, grief, guilt, hopelessness, deteriorated relationships with family, loss of social support, loss of faith, poor self-image, social isolation, intimacy difficulties, intrusive imagery, suicidal ideation, self-hatred, and sexual dysfunction. Also, conversion therapy has VERY high drop out rates, a good indicator in research of a treatment that is causing harm.
Further, practicing conversion therapy is a major no-no ethically and will get you de-licensed. Reason being, it is unethical to treat something that is NOT a disorder... and since homosexuality is not a disorder, herein lies the problem. Conversion therapy tends to stigmatize, adding guilt and shame to an individual.
The biggest problem here is the misunderstanding of the issue. If a client comes to a therapist, having some distress over being gay... or straight for that matter, one must first examine where this is coming from. It probably has zero to do with sexual orientation. This is a sexual disorder, a mood disorder, some other disorder, or some combination, NOT a problem with sexual orientation.
Now, I have no issue with conversion therapy being banned for minors. No one has the right to force a sexual orientation on anyone... including parents. I am involved in this exact situation, currently. The parents have no place to tell my minor client what he or she can be. On the other hand, I see no reason why an adult cannot choose to engage in this form of therapy... if they choose to. They do need to understand that they will be treated by an unlicensed therapist using a type of treatment that has been shown to be harmful, has show to be ineffective, and has been determined to be unethical. If they still want to engage in this treatment... I have no issue with them doing so.