The so-called Trans Law (Law 4/2023, of 28 February, for the actual and effective equality of trans people and the guarantee of the rights of LGBTI people) achieves a crucial intermediate goal: the ruling by the Constitutional Court on one of the appeals filed against some of its contents. There is no denying that this is an extraordinarily complex issue, with multiple facets, perspectives and subtleties. However, upholding the rights recognized by the Spanish Constitutions for every person without exception should always go first.

Since this is an issue of substantial weight and scope, the social debate around it has rarely been calm. This was the case as the law was being developed, and it continues to be so afterwards. The aim of this text is to draw attention to some aspects concerning the implications of the Trans Law for children’s health. This is another pending debate, as it has been scarcely, albeit appreciably, reflected in the pediatric literature in Spanish.1–3

There are pediatric, clinical and ethical aspects inextricably involved in this law. Among the most relevant are the use of drugs whose authorized indications do not include those related to blocking puberty and gender affirmation in these situations; the limited knowledge of the medium- and long-term adverse effects of these drugs and the surgeries performed to adapt the body to the target gender; the cost (and cost-opportunity) of all these interventions for the public health system; and the care provided to meet the mental health needs of involved individuals and families.

Another notable aspect is the scarcity of data on the outcomes of the aforementioned interventions. While we rightly demand evidence, transparency and rigor from medical interventions in every other medical field, it seems that obscurity is accepted when it comes to pharmacological and surgical interventions involving these children and adolescents.

Finally, an aspect that is rarely considered is the impact on children’s health of the inexplicable limitation or omission of psychological evaluations,4 support for families and empowerment of parents in guiding the health education and medical treatment of their underage children, as contemplated by the law, in some cases to the shocking point of questioning legal custody when they express uncertainty or hesitation regarding social transition or gender-affirming care options for their children.

We must urgently stop and think before we continue to pursue health care interventions for which the evidence is scarce that can cause potentially irreparable harm. This is an opportunity for us to reflect on human complexity and our responsibility to do no harm.5