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Semaglutide Weight Loss Side Effects: A Comprehensive Guide

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Dr. Hardik Soni

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Straight to the point – everything you need to know about Semaglutide, weight loss, and potential side effects.

What Is Semaglutide and How Does It Work?

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist used for type 2 diabetes and weight management. It works by mimicking the effects of the naturally occurring hormone GLP-1.

Some key points:

  • Semaglutide binds to and activates GLP-1 receptors in the pancreas and brain. This helps regulate blood sugar levels for diabetes. 
  • It suppresses appetite by targeting areas of the brain that control food intake and reward pathways. This leads to eating less and feeling fuller.
  • In clinical trials, semaglutide has been shown to promote significant weight loss when used for obesity. Patients can lose up to 15% of their body weight on average.
  • The appetite-suppressing effects start working within a few weeks. Maximum weight loss is generally achieved within a year. Weight maintenance requires continuing treatment.

Semaglutide is administered through weekly subcutaneous injection under the brand names Ozempic and Rybelsus.

Is Semaglutide a New Medication?

Semaglutide is not a new medication. Semaglutide was first approved by the FDA in 2017 under the brand name Ozempic as a treatment for type 2 diabetes.

In 2021, the FDA approved Semaglutide under the brand name Wegovy for chronic weight management. Since then, several studies have found Semaglutide to be an effective treatment for weight loss.

While Semaglutide was originally developed as a diabetes medication, its use has expanded to also treat obesity. It remains one of the most effective prescription weight loss medications currently available.

In 2023, a new similar drug called Tirzepatide was approved that may compete with Semaglutide for weight loss. However, Semaglutide itself has been an approved prescription for over 5 years now.

How Effective Is Semaglutide for Weight Loss?

semaglutide weight loss side effects

Research studies have found that semaglutide injections resulted in average weight loss of 15% of body weight at 2 years when used at the 2.4 mg dose.

In clinical trials, around 70% of participants on semaglutide achieved at least 10% weight loss, and around 50% achieved 15% or more weight loss.

Real-world evidence also suggests semaglutide is clinically effective for weight loss of 3-6 months for people with overweight or obesity.

The degree of weight loss achieved with bariatric surgery is usually much greater than what can be expected from lifestyle and medication treatment alone. However, semaglutide provides a non-surgical option that can result in significant weight loss for eligible individuals.

What Is the Recommended Dosage of Semaglutide for Weight Loss?

The recommended starting dosage of semaglutide for weight loss is 0.25 mg injected subcutaneously (under the skin) once per week

After 4 weeks, the dosage may be increased to 0.5 mg based on patient tolerance and weight loss results. Higher dosages up to 2.4 mg once weekly have also shown effectiveness for weight loss.

What Are the Different Types of Semaglutide?

There are different brand names for semaglutide:

Ozempic – Approved in 2017 for treatment of type 2 diabetes. Comes in a pre-filled pen for once-weekly injection.

Wegovy – Approved in 2021 specifically for weight management. Also a once-weekly injection in a pre-filled pen.

Rybelus – An oral tablet form of semaglutide approved for type 2 diabetes. Taken once daily.

The active ingredient, semaglutide, is the same across all brands, but they differ in dosage forms and approved indications. 

Ozempic and Wegovy are injectable while Rybelus is oral. Ozempic is indicated for diabetes treatment while Wegovy is approved specifically for weight loss.

Ozempic vs. Wegovy: What’s the Difference?

The main difference between Ozempic and Wegovy is the dosage of semaglutide. Both are injectable medications containing semaglutide to treat type 2 diabetes and aid in weight loss.


  • Ozempic is approved by the FDA to treat type 2 diabetes. It contains 0.5mg or 1mg of semaglutide per dose. 
  • Wegovy is approved for chronic weight management. It contains higher doses of semaglutide, starting at 0.25mg and increasing up to 2.4mg per dose. Wegovy is intended for individuals who are obese or overweight with at least one weight-related comorbidity.
  • Both drugs come in pre-filled injection pens and are prescribed as weekly injections under the skin. 
  • While they contain the same active drug, Ozempic and Wegovy have different FDA-approved uses and dosage levels due to the higher concentration of semaglutide in Wegovy.

How Does Semaglutide Work for Weight Loss?

Semaglutide works for weight loss by mimicking a hormone called glucagon-like peptide-1 (GLP-1) which targets areas of the brain that regulate appetite and fullness.

It binds to and activates GLP-1 receptors in the pancreas and other organs involved in metabolic processes like the stomach, intestines and brain.

This induces satiety and makes people feel full after eating smaller amounts of food. It suppresses appetite by slowing down gastric emptying and increasing the feeling of fullness.

Over time, eating less calories due to reduced appetite and feeling fuller can lead to weight loss. Clinical trials have shown people losing on average 15% of their body weight when taking semaglutide.

Weight loss occurs as semaglutide is meant to be taken long term as a treatment for obesity, not a short term diet.

How Is Semaglutide Administered?

semaglutide weight loss side effects

Semaglutide is administered through subcutaneous injection under the skin, according to the context provided.

It is usually injected once weekly in the upper leg, stomach area, or upper arm. The starting dose is typically 0.25 mg once weekly for 4 weeks, which may then be increased by the prescribing doctor based on treatment needs and tolerability.

Injection can be done at any time of the day, with or without meals. It is recommended to administer the injection at least 30 minutes before the first food or drink of the day, or other oral medications.

If a dose is missed, the user should typically skip the missed dose and take the next scheduled dose, maintaining the regular weekly schedule.

How Long Does It Take for Semaglutide To Work?

Most patients see some weight loss within the first 4 weeks of treatment with semaglutide. However, the full effects can take up to 3 months.

Blood sugar levels for diabetes treatment should start declining within the first week of using semaglutide.

Studies show continued use of semaglutide helps people lose weight and keep it off for over a year. However, individual results may vary.

A study found patients experienced over 5% weight loss on average after just 4 weeks on semaglutide.

Patience is required as it may take several weeks to see the full effects of semaglutide for diabetes or weight loss treatment.

How Does Semaglutide Help With Diabetes?

  • Increases levels of insulin when blood sugar levels rise, which helps control blood sugar
  • Decreases levels of glucagon when blood sugar levels fall, to prevent large swings in blood sugar levels
  • Slows digestion and absorption of food to reduce post-meal blood sugar spikes
  • Promotes a feeling of fullness to help with weight loss, which can help manage diabetes

Is Semaglutide Only for Diabetes or Can It Be Used for Weight Loss Alone?

Semaglutide formulations like Ozempic are for diabetes, while Wegovy is approved to be used specifically for weight loss even without diabetes. 

But all formulations show weight loss effects that can help manage both conditions together.

What Are the Side Effects of Semaglutide for Diabetes?

Some common side effects of semaglutide injections for diabetes treatment include:

  • Nausea – Around 25% of people experience nausea when first starting semaglutide treatment. This side effect usually lessens over time.
  • Diarrhea – Around 9% of people taking semaglutide for diabetes experience diarrhea. 
  • Constipation – Constipation is listed as a potential side effect on product labeling. 
  • Vomiting – Vomiting can occur but is less common than nausea. 
  • Dizziness and fatigue have also been reported as potential side effects.
  • Hypoglycemia (low blood sugar) is possible but less likely with semaglutide than other diabetes medications since it does not stimulate insulin secretion. Risk can be increased if also taking insulin or sulfonylureas. 

Semaglutide is generally well tolerated. Side effects are usually mild to moderate and lessen for most people over time. People should discuss any side effects with their healthcare provider.

What Is the Recommended Dosage of Semaglutide for Diabetes?

The recommended starting dosage of semaglutide for diabetes is 0.25 mg injected under the skin once weekly for 4 weeks. 

After 4 weeks, the dosage may be increased based on the patient’s glycemic control and tolerability. The maximum recommended dosage is 2 mg once weekly.

Higher doses of oral semaglutide have shown improved blood sugar control at dosages of 25 mg and 50 mg once daily. However, the standard injectable form remains at 2 mg once weekly.

Are There Any Prescription Alternatives to Injectable Semaglutide?

oral semaglutide

There are a few prescription alternatives to injectable semaglutide:

Rybelsus (oral semaglutide) is an oral version of semaglutide used for Type 2 diabetes. It is the only oral GLP-1 medication currently available.

Wegovy is another injectable medication made with semaglutide, the active ingredient in Ozempic, but at a higher dose.

Other GLP-1 receptor agonists available by prescription include injectable medications like dulaglutide, exenatide, and liraglutide.

Some pharmacies have also been offering unauthorized compounded versions of semaglutide in an injectable form. 

However, Rybelsus is the only FDA-approved oral alternative. All other alternatives are currently only available as injectable formulations requiring prescription.

Can I Buy Semaglutide Over the Counter?

Semaglutide is not available over-the-counter. Semaglutide requires a prescription from a licensed healthcare professional. 

While some compounding pharmacies may offer unauthorized alternatives due to drug shortages, the FDA only recommends obtaining semaglutide with a valid prescription.

Dr. Hardik Soni

MD, Founder/Lead Physician

About Dr. Hardik Soni

Dr. Hardik Soni is the founder and Medical Director of Ethos Aesthetics + Wellness. His primary focus is on minimally invasive and non-invasive cosmetic procedures including botulinum injection (Botox and Dysport), dermal fillers (Juvederm, Restylane, Radiesse), laser hair removal, chemical peels, and laser skin rejuvenation. Dr. Soni believes in a more conservative approach and his first goal is education. Clients are able to determine the ideal treatments after discussion with Dr. Soni regarding the expected outcomes, cost, as well as risks.

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