The Side Effects of Peptides – All Peptides Listed

Peptides are amazing tools that can aid in fat loss, health, and anti-aging. Some, however, might have side effects.

Peptides can be intimidating, I get it. Sure, they brag about granting improvements in health, muscle growth, fat loss, aging, healing, and even your credit score.

Ok, so maybe not the last one, but they really do make a difference in your overall health. That said, just like your credit score, they ain’t perfect.

Yes, peptides have side effects. There’s no use in lying to you, and there’s no point in you avoiding that fact.

However, the side effects are not the same for all of these amino acids. No, just like the different James Bonds throughout history, each has its own benefits and drawbacks.

(PS. Pierce Brosnan was the best, and you can’t convince me otherwise.)

Warning: The content on and the information included in this article is intended for entertainment and informational purposes only. It is not intended nor implied to be a substitute for professional medical advice. Prior to buying anything, check that it is compliant where you live with your current government laws. We frequently mention research chemicals that are not made for human consumption. Therefore, before purchasing any product for personal use, consult with your doctor or healthcare provider first.

Key Takeaways

  • Peptides do have side effects, but it depends on which peptides you use
  • Most of the side effects can be avoided by using reasonable dosages and listening to a medical professional
  • Professional athletes and fitness enthusiasts who abuse the peptides are far more likely to experience the side effects

Common Side Effects of Peptides

Peptides ๐Ÿ’‰Side effects โš ๏ธRecent Studies ๐Ÿ“–
AnamorelinQRS complex Tachycardia, stomach discomfort1, 2
AOD 9604Mild headache and diarrhea3
ARA 290Diarrhea, irritability, light-headedness4
BPC-157Headache and dizziness
CerebrolysinVertigo, agitation, hallucinations5
CJC 1295Nausea and itchiness
DSIPOccasional headaches6
EpitalonNausea and maybe cramping7
Follistatin 344Delayed onset of muscular soreness8, 9
GHRP-2Joint ache and carpal tunnel10
GHRP-6Joint ache and carpal tunnel10
GHK-CUHeadache and low Blood pressure11
HexarelinMood swings, fatigue12
HGH FragRedness and swelling, maybe cardiovascular toxicity13
IGF-1Fluid retention, gynecomastia, hypotension14
IGF-1 LR3Hypoglycemia15
IpamorelinHeadaches and flushing16
KPVItchiness and Redness17
ll-37Can promote cancer development18
MacimorelinChange in taste and body ache19
Melanotan INausea and Facial Flushing20
Melanotan IINausea and Facial Flushing20
MGFLow Blood Pressure, Hypoglycemia21
Mots-cNausea and Stomach discomfort22
PentosanJoint pain, stomach upset23
Peg MGFLow Blood Pressure, Hypoglycemia24
PT-141Blurred Vision, Tiredness, Dark Urine25
RU 58841Fatigue, headache, erectile dysfunction26
SemaglutideAnxiety, Bloating27.
SermorelinDifficulty swallowing, dizziness28
SemaxDry mouth, increased sweating
TB 500Swelling and itchiness
TesamorelinArthralgia, myalagia, peripheral edema29
Thymosin Alpha-1local discomfort at the site of injection
Thymosin Beta-4Tiredness and Lethargy
headache and dizzinessFlushing, Heart PalpitationsArthralgia, myalgia, peripheral edema

As you can see in the table above there are a huge number of different peptides each with its own therapeutic effects and potential side effects. This is key.

No two Peptides act identically, thus, their side effects will be different.

And so, it’s important to remember that we cannot compare two peptides directly. Another important factor to remember is that you and I are completely different.

No two humans are identical, thus, the side effects they experience will be different.

Person A might take BPC-157 and not experience any side effects, whereas person B might take BPC-157 and experience some slight abdominal pain.

However, there are some side effects most people report across almost all peptides, most of which should not cause you any real concern.

  • Injection Site Reactions: One of the most common side effects of injectable peptides is local irritation or reactions at the injection site. This can include redness, swelling, pain, or itching. These reactions are usually mild and temporary, resolving on their own without intervention.
  • Allergic Reactions: Some individuals may experience allergic reactions to certain peptides. Symptoms can range from mild to severe and may include rash, hives, itching, difficulty breathing, or swelling of the face, lips, tongue, or throat. This is why we start at lower doses before increasing the dose
  • Gastrointestinal Disturbances: Certain peptides can affect the digestive system, leading to gastrointestinal disturbances such as nausea, vomiting, diarrhea, or stomach discomfort. These side effects are typically transient and resolve on their own.
  • Headache: Headaches are a commonly reported side effect of injectable peptides. They can range from mild to moderate in intensity and usually subside without medical intervention.
  • Anxiety: This will certainly not be present in all individuals, and will subside with time. Folks who are using peptides for the first time might feel nervous and anxious about doing a subcutaneous injection, however, if done correctly this is perfectly safe

As mentioned, these side effects are usually not worth worrying about. There are certain peptides that do pose a risk, sure, but for 99% of the options you’ll come across you’re perfectly fine.

There are general ‘groups’ of peptides, and while these are not identical, they seem to have similar side effects that you would need to take into account.

Peptides for Aging Side Effects

Peptides for Aging include CJC-1295, Ipamorelin, Glutathione, Copper Peptides, Epithalon, Sermorelin, Human Growth Hormone (illegal), etc.

Peptides can be used for ‘anti-aging’, which refers to their ability to fix, suppress, or relieve some of the signs and effects of aging. Aging is still a natural process and no matter how much peptide therapy you use, you simply cannot reverse aging.

Some of these peptides are vastly different from one another, and while most of these will increase collagen production and cellular regenerative properties, the specific peptides are not all interchangeable.

Here are some of the sides you might experience:

  • Decreased insulin sensitivity
  • Slight water retention
  • Loose stool

Peptides for Human Growth Hormone Side Effects

Peptides for Human Growth Hormone include CJC-1295, Ipamorelin, GHRP, GHRH, Hexarelin, etc.

These peptides were specifically developed to increase the production of natural growth hormone. Taking pure growth hormone is illegal without a prescription, and is really only prescribed to those with a deficiency.

Here are some of the sides you might experience:

  • Decreased insulin sensitivity
  • Slight water retention
  • Increased risk of cancer if you are predisposed to it already

Peptides for Hair Growth Side Effects

Peptides for Hair Growth include CJC-1295, Ipamorelin, Copper Peptides, RU58841, and Glutathione.

These peptides are far different from one another. Some will increase blood flow to the scalp while others will decrease stress levels. Thus, there are no real side effects that are ‘shared’ amongst all of these.

Peptides for Weight Loss Side Effects

Peptides for Weight Loss include Semaglutide, AOD-9604, HGH-Frag, Tesamorelin, CJC-1295, Ipamorelin, etc.

These do share quite a few properties amongst one another besides their ability to promote fat loss. They can all help with body fat and an improvement in body composition.

Here are some of the sides you might experience:

  • Loose stool
  • Constipation
  • A great decrease in hunger (not so much a side, but still)

Peptide Side Effects on Women

Without being sexist, the female endocrine and hormonal system is slightly more sensitive compared to the male system. There are far more hormones at play, and even a slight change in these hormones might have dire effects.

However, most peptides would not have ‘more’ negative effects than they would on men purely based on the hormonal system. There are some other things to consider.

  • Women are (on average) lighter than men and would therefore need smaller doses of the same peptides. They have less active tissue, less muscle mass, and more fat mass, thus, they can feel the sides of peptides earlier than men
  • Certain peptides do act on sex hormones and sexual function, like PT141. Whenever you engage in any peptide therapy you need to be sure there are no effects on your sex hormones you are not aware of.
  • Women typically menstruate, which means water retention. If you double down and use a peptide that causes even more water retention, what you end up with is a recipe for hypertension.

Peptide Side Effects in Elderly Women

Young women are more sensitive to peptides than men (in general) and elderly females are even more sensitive than young women.

Everything mentioned above still rings true, however, users would need to be even more careful now:

  • Certain peptides can affect kidney function, which normal individuals can deal with, however, it can cause trouble in elderly women.
  • Peptides that increase water retention need to be used carefully as elderly folks are more susceptible to hypertension.
  • Lastly, any peptide that reacts badly and impairs the immune system should be avoided at all costs by elderly females. With impaired immune function, the risk of illnesses and infections is sky-high.
  • Peptide Side Effects in Elderly Men

The side effects mentioned above will ring true for elderly men as well. However, there are a few additional ones as well:

  • Peptides that boost Testosterone can have an effect on cholesterol and prostate health just by their means to increase Testosterone
  • Peptides that place a strain on the cardiovascular system need to be monitored carefully. Men tend to suffer from more cardiovascular illnesses than women, so, they need to be more careful

Peptides Bodybuilding Side Effects

Bodybuilders (and others who strive for athletic performance) are known for abusing peptides. While this, of course, provides extremely promising results, it allows for significant changes in how these peptides affect the human body.

  • You will likely suffer from insulin resistance, seeing as most Peptides that boost HGH production will lead to this
  • Your organs might take a hit seeing as overdosing on peptides will place significant strain on the kidneys, liver, and heart
  • Your cardiovascular system will also be impaired, and regular cardio is a must

99% of the people who use peptides are not likely to use the amounts that bodybuilders use. Peptides were not created to be used in these amounts. However, if you choose to abuse these amino acids, you will suffer the consequences unless you remedy the situation.

Are Peptides Safe to Use?

For 99% of the individuals who use them, absolutely. Most peptides on the market have undergone extensive research and trials to be approved for human usage. And even those that haven’t are simply a victim of time, not necessarily a bad result.

Your pituitary gland already releases most of the peptides you intend to use anyways, and peptide therapy is simply the replacement of what’s no longer being produced naturally.

More research is being done on peptides and their beneficial effects each and every day, and the results always come back in the same way.

Peptides are safe.

(unless you use way too much…)

Which Peptides Are Not Safe to Use?

While peptide therapy and peptides themselves are safe, there are a few peptides that do pose a risk to those who want to use them.

  • Melanotan II is known as the tanning peptide but is known for placing a strain on the kidneys. If you have impaired kidney function, you need to avoid this
  • Peptides that increase Growth Hormone need to be monitored by those who suffer from Diabetes since they can worsen insulin resistance
  • HCG (Human chorionic gonadotropin) can increase Estrogen in the body dramatically, so, be careful if you are a male
  • Fat loss peptides could cause bouts of low energy, especially when combined with a low-calorie diet

Again, peptides are safe, there might just be a few that are unsafe for you.

๐Ÿ’‰Become a Peptide Expert (Protect your Health) ๐Ÿ’‰

Take our FREE 25-email course to learn everything you need to know about the scientific application of peptides. Discover how to protect your health, avoid sketchy peptide vendors, and stop wasting your hard-earned money. ๐Ÿ”ฅ ๐Ÿงช ๐Ÿ’Š ๐Ÿ’ช ๐Ÿ’‰ ๐Ÿฉธ๐Ÿฅ ๐ŸฅŽ

Where to Buy Safe Peptides?

#3 Great Selection: Core Peptides

Core Peptides, a newly established vendor, has launched with over 78 peptides and blends available on their online platform. The initial lack of Certificates of Analysis (COAs) for every product is a short-term drawback, yet their commitment to rigorous testing and verification before sales underlines a strong emphasis on quality assurance.

The early phase has been promising with positive feedback from numerous satisfied customers, showcasing their dedication to transparency and quality control. Their promise of providing COAs soon and continuous improvement in testing procedures reflects a responsible approach to meet or exceed industry standards.

The demand for peptides and blends extends beyond health and fitness to crucial sectors like research and development. Core Peptides appears to understand this market dynamic well, aligning their business ethos with providing high-quality products to meet current market demands.

The entrance of Core Peptides into the market is seen as a positive development. With a growing array of products, steadfast dedication to transparency, and robust quality control measures, they’re on a trajectory towards becoming a trusted and reliable vendor. Early positive customer interactions highlight Core Peptides as a notable new player in this domain.

Core Peptides Overview

๐Ÿ’Š ๐Ÿงช Forms:ย Injectable, topical, and peptide blends
๐Ÿ“„ Lab Verified (COA):ย Mostly, but constantly being updated with new tests
๐Ÿ“ฌ Shipping Policy:ย Free for $200+, Flat rate $9.95, Priority or $49.95 for Overnight
๐Ÿ’ต Payment Methods:ย Credit cards, Venmo, Zelle, CashApp
โœ… Guarantees:ย Free exchange for damaged product
๐Ÿ”– Promo Codes: None
๐Ÿท Price (BPC157 5mg equivalent):ย $47
โญ๏ธ Rating:ย 4.8
โžก๏ธย Go to Full review

  • Extensive variety of peptides and blends catering to diverse needs.
  • Unyielding commitment to quality control and transparency, promising a future with comprehensive product testing.
  • Encouraging initial customer feedback suggesting a positive market reception.
  • Lack of Certificates of Analysis (COAs) for every product, a temporary but significant hurdle.
  • The newcomer status in the industry might entail a journey towards building a solid reputation and trust.

The big question left, of course, is whether or not peptides are legal. We all know that avoiding a run-in with the law is key to a long and happy life, and so is more Growth Hormone.

  • Peptide therapy via a registered clinic is perfectly legal
  • Peptides purchased as ‘research chemicals’ are perfectly legal
  • Certain Peptides are illegal point blank, like Human Growth Hormone

You can either get your peptide therapy from a clinic or from a vendor. The former will have you engage with a medical professional who will prescribe certain peptides approved for human usage.

Vendors sell any peptide that is listed as a ‘research chemical’. These can be purchased by normal people, but the label must state ‘not for human use’.


Are peptides safe to use?

Peptides can be safe when used appropriately and under the guidance of a qualified healthcare professional. However, like any medication or therapeutic intervention, there can be potential side effects associated with peptide therapy.

What are the common side effects of peptide therapy?

The specific side effects of peptide therapy can vary depending on the type of peptide used and individual response. However, some commonly reported side effects may include injection site reactions (such as redness, swelling, or pain), headaches, nausea, fatigue, changes in appetite, or alterations in hormone levels.

Are there any long-term side effects of peptide therapy?

Since peptide therapy is a relatively new field, the long-term effects of many peptides are still being studied. While most peptides are generally well-tolerated, the long-term impact of prolonged or excessive use of certain peptides is not yet fully understood.

Can peptides interact with other medications?

Peptides can potentially interact with other medications. It’s important to inform your healthcare provider about any medications, supplements, or herbal remedies you are currently taking before starting peptide therapy. They can evaluate potential interactions and make necessary adjustments to ensure your safety and optimize treatment outcomes.

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Kumar Rathi

Kumar Rathi | Writer

Kartik is a medical student with a passion for anatomy and physiology. He writes research papers, articles and blogs to raise awareness and also has a strong interest in teaching and public speaking. Aspiring to be a successful cardiologist, Kartik believes in connecting with people on a personal level and is an expert in peptides.

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