Some people struggle to gain weight when their doctor or nutritionist recommends it or when trying to build muscle mass. This happens for various reasons: some are genetically thin; some battle genetic or autoimmune diseases that make it hard to put on weight; some have a low appetite or disordered eating that leads to inadequate food intake; and some want to put on muscle but find it a struggle. 

A recent trend in the weight-gain industry had people turning to an illicit supplement—apetamin pills. Banned from sale in the U.S., consumers are forced to purchase apetamin from small online websites or social media. Learn how apetamin works for weight gain, why it’s illegal, and its side effects.

What Is Apetamin?

Apetamin is a vitamin supplement used for weight gain. According to manufacturing labels and a product list from the company that developed apetamin (TIL Healthcare), apetamin syrup contains a combination of a prescription-only medication called cyproheptadine hydrochloride, vitamins, and amino acids (namely lysine). TIL Healthcare has several appetite-stimulant products that contain cyproheptadine hydrochloride.

This combination of lysine, vitamins, and cyproheptadine hydrochloride is said to act as an appetite stimulant and increase the amount of food you can eat in a day. However, neither vitamins nor amino acids are known to increase appetite. Cyproheptadine hydrochloride is an antihistamine (a medicine that alleviates allergy symptoms) that has increased appetite listed as a known side effect. 

Why People Take Apetamin

The main reason for taking apetamin is to gain weight. Cyproheptadine hydrochloride has been used as an appetite stimulant in medical settings, particularly for patients with cystic fibrosis where low appetite is a side effect. It’s also been used to help malnourished children gain weight.

People have used apetamin syrups and pills to help gain muscle, get stronger, and prepare for events like powerlifting and bodybuilding shows. Many naturally thin women have also used apetamin products to add curves to their figures. 

However, this singular benefit of apetamin—weight gain—does not outweigh the known side effects. 

How Does Apetamin Work? 

Consumers believe apetamin promotes weight gain because of its active ingredient of cyproheptadine hydrochloride. This powerful antihistamine has been used as an appetite stimulant in malnourished children and people with chronic diseases, such as cystic fibrosis.

Researchers and doctors aren’t entirely sure why cyproheptadine hydrochloride stimulates appetite, but a few possible scenarios exist. 

For example, cyproheptadine hydrochloride may increase insulin-like growth factor hormone (IFG-1) in underweight children. This hormone has been linked to weight gain in malnourished children.

Cyproheptadine hydrochloride may also interfere with your brain's hypothalamus, the small section that regulates appetite, cravings, food consumption, and many other hormones.

In animal studies, L-lysine, the amino acid found in apetamin syrup, has led to increased appetite and weight gain. Still, there’s no research on the appetite effects of l-lysine in humans.

Much more research is needed to determine whether apetamin is an effective—and safe—weight gain supplement for humans. 

Apetamin Pills Versus Syrup

Apetamin syrup is more common than the pill form, the main difference being that apetamin syrup contains a blend of vitamins and amino acids while tablets or caplets contain cyproheptadine hydrochloride.

Is Apetamin Legal? 

It’s currently illegal to sell apetamin in many countries, including the U.S., because apetamin products contain a prescription-only drug called cyproheptadine hydrochloride. Cyproheptadine hydrochloride is an antihistamine used to treat allergy symptoms such as sneezing, itchy and watery eyes, and runny nose. 

It’s only available with a prescription due to its potential side effects and safety concerns, which, on the severe side, include liver failure. Additionally, the FDA has not approved and does not regulate apetamin, which means that some (and possibly many) apetamin products don’t accurately disclose what they contain. This presents the risk of toxicity from any undisclosed ingredients. 

Apetamin and other products that contain cyproheptadine hydrochloride are even on the FDA’s list of illegal medical imports to be seized and of unapproved cough, cold, and allergy products. Because of these reasons, you won’t find apetamin at reputable food, vitamin, or supplement stores in the U.S. 

Side Effects of Apetamin

The side effects of apetamin pills and syrup arise mainly from its active ingredient of cyproheptadine hydrochloride. According to the U.S. Library of Medicine, side effects include: 

• Dry mouth
• Dry sinuses and throat
• Drowsiness and fatigue
• Dizziness
• Nausea
• Chest congestion
• Headache
• Excitement or hyperactivity (particularly in children)
• Muscle weakness

In the worst-case scenario, using apetamin or unprescribed cyproheptadine hydrochloride can lead to liver toxicity and liver failure. Excessive weight gain or obesity is also a risk for those who overuse apetamin.

Is It Safe to Use Apetamin for Weight Gain?

Because of legality issues and lack of regulation from the FDA, you can’t trust apetamin products to contain what they say they have on the label. Additionally, side effects of the active ingredient cyproheptadine hydrochloride can be severe without a prescription (and even with a prescription). For those reasons, it’s unsafe to use apetamin for weight gain. 

A Word From Verywell

If you’re looking to gain weight, it’s possible to do so without using illegal supplements. Just like weight loss, intentional weight gain requires a diet and exercise plan tailored to your goals. 

Health professionals who can help you create a plan include doctors, registered dietitians, and personal trainers. Most people can safely and effectively gain weight by eating more calories than they burn, focusing on protein intake, and building muscle by lifting weights.