The 4 pillars of medical ethics are:

• Beneficence means that practitioners should act as they believe is in the best interest of the patient. Unlike non-maleficence, it goes beyond simply doing no harm and encourages to actively help others. Beneficence is important because it ensures that healthcare professionals consider individual circumstances and remember that what is good for one patient may not necessarily be great for another.
• Non-maleficence means that a physician has a duty to ‘do no harm’ to a patient. It directs a medical professional to consider the benefits of all procedures and weigh them against the potential risks and burdens on the patient. The concept of non-maleficence is derived from the Latin phrase “primum non nocere” (“first, do no harm”). It can be applied to assessing the risks of medical procedures – or ensuring that all treatments and medical advice are administered by professionals with appropriate qualifications.
• Patient autonomy recognizes the rights of patients to make decisions about their own healthcare. It is patients that have the ultimate authority to determine what happens to their bodies and to participate in the decision-making process regarding their treatment options. In other words, healthcare professionals cannot impose treatments or interventions on patients without their informed consent. Instead, they must provide patients with all relevant information, including potential risks, benefits, and alternatives, to enable them to make informed decisions about their care. The only exception is in cases where the patient is deemed unable to make autonomous decisions (e.g., mentally incapacitated).
• Justice requires that when weighing up if something is ethical or not, we have to think about whether it’s compatible with the law, the patient’s rights, and if it’s fair and balanced. It also means that we must ensure no one is unfairly disadvantaged when it comes to access to healthcare. 

One clarifying additional point:

Non-maleficence differs from beneficence in two major ways. First of all, it acts as a threshold for treatment. If a treatment causes more harm than good, then it should not be considered. This is in contrast to beneficence, where we consider all valid treatment options and then rank them in order of preference. Second, we tend to use beneficence in response to a specific situation – such as determining the best treatment for a patient. In contrast, non-maleficence is a constant in clinical practice.