Peptide and GLP-1 Side Effects: What to Know
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[Guide · Protocols and safety]

Side effects: what to know

6 min read · Also in the Dose Track app under Learn · Updated

Short answer: Side effects depend on the class. GLP-1 drugs mostly cause stomach and gut symptoms, especially when the dose goes up. Growth hormone peptides can cause water retention, tingling hands and hunger. Most side effects rise with the dose. Allergic reactions, spreading infection, severe stomach pain and chest symptoms mean stop and get help.

Why it depends on the class

GLP-1 drugs (semaglutide, tirzepatide, liraglutide) act on gut and brain receptors that control appetite, stomach emptying and insulin. Their side effects are mostly digestive. They are approved drugs, so their labels list exact rates.

Growth hormone peptides (ipamorelin, CJC-1295, sermorelin, GHRP-2, GHRP-6) raise growth hormone and IGF-1. Their side effects mostly follow from that.

Repair peptides (BPC-157, TB-500) have very little human safety data. "No reported side effects" is not the same as "shown to be safe".

GLP-1 drugs

Nausea in the trials, from the FDA labels
Drug and doseNausea on the drugNausea on placebo
Ozempic 0.5 mg15.8%6.1%
Ozempic 1 mg20.3%6.1%
Wegovy 2.4 mg44%16%

Vomiting, diarrhea, constipation and stomach pain are also common, mostly when starting or after a dose increase. That is why these drugs start low and step up.

Rare but serious, from the labels: pancreatitis (severe stomach pain that may go through to the back), gallbladder problems, severe stomach and gut reactions, and low blood sugar when used with insulin or sulfonylureas. They carry a boxed warning about thyroid C-cell tumors seen in rodents; people with a personal or family history of medullary thyroid cancer or MEN 2 should not use them.

Growth hormone peptides

Research info, not a recommendation. Amounts, schedules and timing in this section come from studies (often in animals) and from how people commonly use these compounds. Most are not FDA-approved doses. Your dose is a decision for you and your prescriber.

These come from raised growth hormone and IGF-1, and are the same kinds of effects listed on growth hormone drug labels:

  • Water retention (puffy hands, feet, ankles).
  • Tingling or numbness in the hands, like carpal tunnel. Swelling in one leg only, weakness, or shortness of breath is something else; get it checked.
  • Joint aches.
  • Hunger, strongest with GHRP-6 and GHRP-2, which act like the hunger hormone ghrelin. Ipamorelin causes less.
  • Higher blood sugar over time; check fasting glucose or HbA1c.
  • Cortisol and prolactin rises with GHRP-2 and GHRP-6. Ipamorelin was chosen in part because, in animal studies, it did not raise them (Raun 1998).

These usually rise with the dose. If they show up, talk to your prescriber about lowering it rather than pushing through.

Injection site reactions

Normal or not
What you seeWhat it usually means
Small welt, mild redness or itch that fades within hoursNormal
Small bruiseA tiny blood vessel was nicked; harmless
Redness that spreads, or warmth that keeps growing after a dayPossible infection; see a clinician
Soft, fluid-filled lumpPossible abscess; see a clinician
Red streaks or feverSee a clinician promptly

When to stop and get help

  • Allergic reaction: hives, swelling of the face, lips or throat, trouble breathing, or feeling faint after a dose. Use an epinephrine auto-injector if you have one and call emergency services.
  • Infection signs at a site: spreading redness, pus, red streaks, fever.
  • Severe stomach pain, especially through to the back, on a GLP-1 drug.
  • Chest pain, fainting, or new irregular heartbeat.

If you are unsure whether a symptom is from your medicine, pause and get checked.

Log symptoms with your doses

Side effects often lag days behind a dose change, which is too long for memory to connect. Logging the dose, time, site and any symptoms gives you and your prescriber a timeline. Dose Track has a side effects log for this.

Key points

  • GLP-1 side effects are mostly digestive and peak when starting or raising the dose.
  • Growth hormone peptides can cause water retention, tingling hands, joint aches, hunger and higher blood sugar.
  • Repair peptides have little human safety data.
  • Allergic reaction, infection signs, severe stomach pain or chest symptoms mean stop and get help.

See also: Side effects from FDA labels · Side effects log in Dose Track

This guide is general education, not medical advice. Follow your medicine's label and your prescriber.

Compounds in this guide

SemaglutideCompound guide in the Dose Track library. TirzepatideCompound guide in the Dose Track library. IpamorelinCompound guide in the Dose Track library. GHRP-6Compound guide in the Dose Track library. BPC-157Compound guide in the Dose Track library.
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Frequently asked questions

How common is nausea on semaglutide?+
In the Ozempic trials, 15.8% at 0.5 mg and 20.3% at 1 mg had nausea versus 6.1% on placebo. On Wegovy 2.4 mg it was 44% versus 16%.
What are the side effects of growth hormone peptides?+
Commonly water retention, tingling hands, joint aches, more hunger with GHRP-6 or GHRP-2, and higher blood sugar over time.
When is stomach pain on a GLP-1 drug serious?+
Severe stomach pain that will not go away, especially going through to the back, can be pancreatitis. Stop and get medical care.

Sources

  1. Ozempic prescribing information and Instructions for Use (Novo Nordisk)
  2. Wegovy prescribing information and Instructions for Use (Novo Nordisk)
  3. Zepbound prescribing information and Instructions for Use, single-dose pen and KwikPen (Eli Lilly)
  4. Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998;139(5):552-61

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