Consent must be voluntary and informed if it is to be deemed valid, whilst the person consenting must have the capacity to do so. Clinicians must respect the decision of an adult who has the capacity to make a voluntary and informed decision, regardless of the consequences. If, however, an adult does not have capacity, clinicians can administer treatment if it is in the best interest of the patient. In such instances, clinicians should seek guidance from the patient’s relatives or friends.