Joana arrived at the emergency room with severe abdominal pain, unrelenting vomiting, and significant weakness. She had been self-administering a "weight loss pen" purchased on a friend's recommendation, without a prescription and without seeing a doctor first. She needed to be hospitalized for investigation and treatment.

Unfortunately, this type of scene has become more common in Brazilian emergency rooms. In my assessment, there is a lack of clear information about what these pens really are, what they are used for, and most importantly, about the risks of using them without medical guidance. This is what I want to explain in a simple way in this article.

"The data and clinical case cited in this article are fictional and serve merely illustrative purposes, helping to facilitate understanding of the topic addressed."

What are weight loss pens

"Weight loss pen" is the popular name for a type of injectable medication originally used to treat type 2 diabetes. This medication mimics the action of a hormone that the intestine naturally produces, called GLP-1, which helps control blood sugar and the sensation of hunger.

Over time, doctors realized that this same medication also helped with weight loss. For this reason, some of these pens began to be approved also for the treatment of obesity, always with medical indication and well-defined criteria.

An important point: these pens are not "cosmetic products" nor can they be used by anyone who wants to lose weight. They are real medications, with contraindications, possible side effects, and the need for medical monitoring throughout treatment.

How these medications work in the body

The GLP-1 hormone does several things in the body: it helps the body release insulin when blood sugar is high, makes digestion slower, and sends the brain the sensation of a full stomach. In practice, this means less hunger, more satiety, and better controlled blood sugar.

The weight loss pens mimic this hormone (some newer versions mimic more than one hormone at the same time), making this effect last longer in the body.

The substances most used today

There are different types of pens on the market, and it is common for people to confuse one with the other:

  • Semaglutide: used for type 2 diabetes and, in another version, for obesity.
  • Liraglutide: also used for type 2 diabetes and, in another version, for obesity.
  • Dulaglutide: applied once per week, used for type 2 diabetes.
  • Tirzepatide: works slightly differently from the others, mimicking two hormones at the same time, which increases the effect on blood sugar and weight. Used for type 2 diabetes and, more recently, also for obesity.
  • Retatrutide: mimics three different hormones. It is still being tested in research and, to date, does not have approval for sale in Brazil.

Each of these substances works in its own way and has different side effects. That is why the right medication, in the right dose, is always a decision that needs to be individual, made with a doctor, and never copied from another person just because "it worked" for them.

The risks of using without medical supervision

When these medications are used without evaluation and without a doctor monitoring, some problems become more common:

  • Severe nausea, vomiting, and diarrhea, which can lead to dehydration.
  • Drop in blood sugar (hypoglycemia), especially in those who already take other diabetes medications.
  • Pancreatitis, an inflammation of the pancreas that can be serious and require hospitalization.
  • Loss of muscle mass, when weight loss is very rapid and is not accompanied by guidance on diet and, when indicated, physical activity.
  • Dosing error, especially in products that require drawing the medication from a vial with a syringe, a step where it is easier to make mistakes than with pre-filled pens with the correct dose.
  • Use by people who wouldn't even need the medication, which brings the risks without bringing any real benefit.

The Brazilian health authorities have recorded an increase in warnings of serious effects linked to these medications, including cases of pancreatitis and deaths that are still being investigated. This reinforces why this type of medication should only be used with a prescription and medical supervision.

Pens brought from other countries: what a Unicamp study showed

There has been growing purchasing of weight loss pens manufactured in other countries, usually because they are cheaper. One point that often generates confusion is the following: an analysis conducted by Unicamp researchers found the same tirzepatide substance in samples of products manufactured in Paraguay. In other words, the substance itself was identified in these products.

But that does not mean that these products are safe or of guaranteed quality. The study itself did not evaluate essential points, such as whether there were impurities, contamination, or whether the product was truly sterile, nor did it test whether the medication works and is safe as it should be. According to Anvisa, evaluating whether a medication is safe goes far beyond knowing what substance it contains: it is necessary to evaluate how it was manufactured, how it was stored, and, most importantly, how it was transported.

And it is precisely at this point that the greatest risk lies. These medications, in general, need to be kept refrigerated and transported with great care. When this care is not guaranteed from the beginning to the end of the journey, from the place where the medication was manufactured to the home of whoever will use it, the quality and safety of the product are compromised, even if the substance inside the vial is correct.

Factors that increase the risk

Some factors make the use of these medications even more dangerous:

  • Using without a diagnosis or clear medical indication.
  • Not having exams before starting or monitoring during use.
  • Mixing with other medications on your own.
  • Having a personal or family history of pancreatitis or thyroid disease, which requires careful evaluation before starting.
  • Increasing the dose on your own, without following the schedule recommended by the doctor.
  • Buying through social networks or from sellers without guarantee of origin.

Frequently asked questions

Can anyone who wants to lose weight use a weight loss pen? No. It is a medication with a specific medical indication, evaluated case by case, taking into account the health history, exams, and other factors of each person.

Is it safe to use without a medical prescription? No. Using without a prescription and without supervision increases the risk of serious effects and prevents the dose from being adjusted correctly for each person.

If the substance is the same, is the product safe? Not necessarily. Knowing which substance the product contains is only one part of the safety evaluation. Purity, absence of contamination, method of manufacture, and method of transport are also fundamental.

Does every pen in this class work for weight loss? No. Some have indication only for type 2 diabetes. The indication for obesity depends on which substance it is, the dose, and the specific registration of that product.

What signs indicate that you need to see a doctor during use? Vomiting that does not stop, severe abdominal pain, signs of dehydration, severe dizziness, or any unusual symptom are reasons to seek medical attention as soon as possible.

This content is informative and educational in nature and does not replace medical consultation. Each organism responds differently to any medication, and decisions about starting, adjusting, or stopping treatment should always be made with a doctor.

Dr. Rebeca Soares Andrade CRM - GO 39335