ItalianoMedications designed to support weight loss have helped many people shed pounds and maintain their progress over time. These drugs are often an integral component of a broader plan to manage obesity. If you’re a healthcare provider assisting patients with weight concerns, chances are high that you’ve encountered questions about these medications—especially newer options like semaglutide and liraglutide. Given the attention these drugs receive in the media, concerns about potential side effects are increasingly common.
Scientific investigations have started to focus on the adverse effects of medications such as GLP-1 receptor agonists. For instance, a study featured in JAMA in late 2023 documented gastrointestinal side effects from mild nausea to more severe issues like pancreatitis.
Because discontinuing these medications often results in significant weight regain, it’s crucial that anyone considering them understands the possible risks involved.
If a patient is reluctant to start a particular medication due to concerns about side effects, alternatives may be worth exploring. There’s a wide array of drugs available that work on different biological pathways related to hunger, satiety, and metabolism. Tailoring treatment to the individual’s profile is key for long-term success.
Whether you’re a clinician prescribing these medications or a patient thinking about discussing them with your doctor, having clear expectations about possible side effects will help with planning and preparedness.
Eligibility Criteria for Weight Loss Medications
The primary metric for determining who can take weight loss medications is the body mass index (BMI). The Centers for Disease Control and Prevention offers a BMI calculator for adults on their website.
For drugs like semaglutide and liraglutide, eligibility typically includes adults or adolescents aged 12 and up who have a BMI of 30 or higher. Individuals with a BMI of 27 or above may also qualify if they have related health conditions such as hypertension, high cholesterol, or diabetes. In these cases, the presence of comorbidities helps justify medical intervention, although a BMI of 30+ alone is sufficient due to obesity being classified as a chronic disease.
The eligibility criteria for other medications—such as orlistat, phentermine, and the naltrexone-bupropion combination—are largely similar, although not all are approved for use in younger populations.
Tirzepatide, a more recent addition to the pharmaceutical toolbox, is currently approved only for adults with a BMI of at least 30. This drug is unique in that it acts on both GLP-1 and GIP receptors, similar to some other medications still undergoing clinical trials.
Increasing Scrutiny Over Gastrointestinal Side Effects from Popular Weight Loss Drugs
As more people use these medications, and as they remain on the market longer, we are learning more about their long-term safety and side effect profiles. With GLP-1 and GIP receptor agonists in the spotlight, it’s no surprise that questions about digestive side effects are becoming more common.
One study conducted in 2023 found that nearly 70% of individuals using semaglutide or liraglutide discontinued treatment within a year.
There are many potential explanations for this trend—ranging from adverse side effects to limited insurance coverage or even supply shortages. Regardless of the cause, this high dropout rate is something to consider when deciding which medication to recommend.
About 4.5% of users in the same study stopped treatment specifically due to side effects. Another research effort focused on semaglutide administered weekly showed a 7% discontinuation rate within one year due to adverse reactions.
The digestive system appears to be the most commonly affected. Many patients report nausea, vomiting, or general stomach discomfort as reasons for stopping. To break it down: approximately 44% of semaglutide users experience nausea, 30% report diarrhea, 24% have vomiting or constipation, 20% suffer from abdominal pain, and smaller percentages note bloating, gas, heartburn, or indigestion.
Overview of Side Effects for Common Weight Loss Medications
Let’s explore the known side effects of several widely used weight loss drugs: phentermine (with or without topiramate), naltrexone-bupropion, liraglutide, semaglutide, orlistat, and tirzepatide. For comprehensive and updated safety information, consult the manufacturer’s guidelines.
1. Phentermine
Phentermine has the distinction of being one of the earliest approved weight loss medications, dating back to 1959. It’s often paired with topiramate to enhance efficacy.
It works primarily by suppressing appetite through central nervous system stimulation. However, it’s not suitable for patients with thyroid issues, heart disease, or glaucoma, nor for those with a history of stroke.
Side effects may include insomnia, elevated blood pressure, restlessness, rapid heartbeat, tremors, and headaches. There’s a risk of interactions with certain substances, including MAO inhibitors, alcohol, sympathomimetics, and specific anesthetics.
2. Phentermine-Topiramate Combination
This combination must be avoided during pregnancy due to potential risks. The dual-action mechanism—curbing appetite and enhancing feelings of fullness—makes it an attractive option.
Adverse effects can include tingling sensations, dizziness, altered taste, constipation, dry mouth, and difficulty sleeping. Individuals with uncontrolled high blood pressure, heart conditions, glaucoma, or sensitivity to stimulants should avoid this medication.
3. Naltrexone-Bupropion
This duo tackles both cravings and appetite, making it a valuable option for many. However, it’s contraindicated for individuals with seizure disorders or those using opioids.
Frequent side effects include nausea, headaches, vomiting, insomnia, dry mouth, dizziness, constipation, and diarrhea.
4 & 5. Liraglutide and Semaglutide
Both liraglutide and semaglutide are injectable drugs, although oral versions exist for managing type 2 diabetes. Liraglutide is administered daily, whereas semaglutide is taken weekly. These medications help enhance satiety and reduce food intake.
Liraglutide’s side effects include nausea, fatigue, constipation, vomiting, diarrhea, dizziness, indigestion, headache, reduced appetite, and abdominal pain. Increases in heart rate and lipase levels may also occur.
For semaglutide, digestive complaints are especially common during the early stages of treatment. To mitigate these effects, doses are often gradually increased. Additional side effects may involve belching, bloating, headaches, dizziness, fatigue, heartburn, fever, and jaundice-like symptoms.
Recent media reports have raised concerns about the potential for semaglutide to increase suicidal thoughts. However, a January 2024 study published in Nature Medicine found that semaglutide users had a significantly lower likelihood—ranging from 49% to 73%—of experiencing suicidal ideation compared to users of other obesity treatments.
The JAMA article referenced earlier compared GLP-1 agonists to naltrexone-bupropion, revealing a heightened risk of conditions like pancreatitis, intestinal blockages, and delayed stomach emptying in those taking GLP-1 drugs.
Ongoing studies will continue to refine our understanding of this medication class, making it essential to stay informed through scientific literature.
6. Orlistat
Orlistat works by inhibiting the digestive enzyme lipase, which breaks down fats. This means dietary fats are excreted rather than absorbed, aiding weight loss.
However, this mechanism often results in gastrointestinal issues. Side effects commonly include oily rectal discharge, frequent bowel movements, and occasional incontinence or flatulence with leakage.
7. Tirzepatide
Initially created for type 2 diabetes, tirzepatide received approval for weight loss use in 2023. As an agonist of both GLP-1 and GIP receptors, it boosts feelings of satiety and helps users adhere to lower-calorie diets.
Side effects include gastrointestinal issues like constipation, bloating, and diarrhea. More serious risks may involve pancreatitis, gallbladder disease, kidney complications, and dangerously low blood sugar levels.
The manufacturer has also issued warnings about the risk of thyroid tumors. Patients should be monitored for symptoms such as difficulty swallowing, persistent hoarseness, neck swelling, or shortness of breath.
Balancing Benefits and Risks When Considering Weight Loss Drugs
While medications can be an effective tool for managing weight as part of a broader treatment approach, they’re not without potential downsides. The key is to weigh the expected benefits against the possible side effects to ensure the chosen drug aligns with the patient’s health profile and goals.