Can peptides cause tiredness?

Each answer says whether tiredness was reported, and how often where that’s known. “Not reported” means the label or trials didn’t list it, not that it can’t happen. Talk to a doctor or pharmacist about any symptom that worries you.

From a product label 13

What the prescribing information says, with rates against placebo where the label gives them.

CerebrolysinApproved drug

LabelRare: fatigue is listed in the EU label, from one study; the labels note such symptoms are common in older patients even without treatment.

ExenatideApproved drug

LabelWeakness (asthenia): 4% vs 2% on placebo in the 30-week trials, and 5% vs 1% when added to insulin glargine.

GHRP-2Approved drug

LabelTiredness (malaise) and sleepiness are each listed at 0.1–5% after the single IV test dose in the Japanese label.

hCGApproved drug

LabelFatigue is listed in the US labels without a rate. A UK label rates tiredness uncommon (under 1 in 100).

L-CarnitineApproved drug

LabelWeakness (asthenia): 9% vs 8% on placebo in the label’s dialysis trials (130 people on IV levocarnitine). A 2022 Cochrane review found it didn’t ease dialysis fatigue.

LiraglutideApproved drug

LabelFatigue: 7.5% vs 4.6% on placebo in Saxenda’s adult trials, and weakness 2.1% vs 0.8%. Mostly in the first 12 weeks, often alongside nausea or vomiting.

Melanotan 1Approved drug

LabelFatigue: 6% vs 3% on placebo implants (US label). The EU label adds sleepiness and lethargy and advises against driving if affected, especially within 72 hours of an implant.

OrforglipronApproved drug

LabelFatigue: 6–9% vs 4% on placebo in the 72-week weight trials, rising with dose.

PT-141Approved drug

LabelFatigue: 3.2% vs 0.5% on placebo in the 24-week trials.

SemaglutideApproved drug

LabelFatigue or weakness: 11% vs 5% on placebo at both 2.4 mg and 7.2 mg.

TirzepatideApproved drug

LabelFatigue or weakness: 5–7% vs 3% on placebo in the weight trials. In Mounjaro’s 4-year heart trial, 10% of people reported fatigue.

TriptorelinApproved drug

LabelWeakness is very common (over 1 in 10) in the UK label. In US prostate cancer trials, fatigue was reported in 2.1–2.3%; those trials had no placebo group.

SermorelinHuman studies

LabelSleepiness (somnolence) occurred in under 1% of 350 patients in the Geref trials, mostly children with GH deficiency.

From human studies 13

What published trials and case reports found.

MazdutideApproved drug

TrialFatigue: 23.1% on 3–16 mg vs 6.4% on placebo in the 56-week US phase 2 trial (177 adults). In a 24-week Chinese trial at 3–6 mg, it stayed under 10%.

OxytocinApproved drug

TrialIn a 24-week nasal trial of 290 children and teens, fatigue matched placebo (5.5% vs 5.6%); sleepiness was 13% vs 8%. During IV use, drowsiness can signal water intoxication.

AOD9604Human studies

TrialFatigue came up 4 times in a 15-man IV study, with side effects spread evenly across doses and placebo. Larger oral trials of up to 24 weeks didn’t flag it.

ARA-290Human studies

TrialTiredness in 5 of 46 people on 1–8 mg vs 2 of 16 on placebo over 28 days in the Phase 2b sarcoidosis trial.

CagrilintideHuman studies

TrialFatigue: 5–20% across doses vs 3% on placebo in the 26-week trial of cagrilintide alone, highest (20%) at 4.5 mg.

Kisspeptin-10Human studies

TrialFatigue in 2 of 18 people given repeated IV doses over 40 hours (no placebo group). FDA’s 2024 review of about 300 people found no serious side effects.

Melanotan 2Human studies

TrialIn the 1996 pilot, 1 of 2 men on the top dose (0.03 mg/kg) had moderate sleepiness and fatigue. Bremelanotide’s label lists fatigue in 3.2% vs 0.5%.

MK-677Human studies

TrialFatigue was among drug-related side effects more common than on placebo in a 563-person Alzheimer’s trial; 3 of 12 adults reported it in a 6-month liver study.

NAD+Human studies

TrialFatigue was among the most common side effects in a review of 10 oral NADH and precursor trials (489 people), none serious. No data for injections.

RetatrutideHuman studies

TrialFatigue: 2.9–12.1% across doses vs 4.3% on placebo in the 48-week phase 2 trial of 338 adults, with no clear rise at higher doses.

SurvodutideHuman studies

TrialFatigue: 10.3% vs 5.7% on placebo in the 48-week SYNCHRONIZE-MASLD trial (216 adults) and 9.4% vs 7.8% in the 46-week phase 2 obesity trial.

Thymosin Beta-4Human studies

TrialRare: weakness in 1 of 53 people on the gel vs 0 of 18 on placebo (pressure ulcers). Not listed in the Chinese IV or large eye-drop trials.

LarazotideHuman studies

TrialNot more common than on placebo; in the 12-week, 342-person trial, tiredness and headache scores were actually lower on 0.5 mg than on placebo.

From user reports 6

Commonly reported by people who use it, not established in a study.

Thymosin Alpha-1Approved drug

CommunityUsers report tiredness or a mild flu-like feeling early on. Neither label lists it; in an early dose study, 1 of 14 people had a fever.

GHK-CuHuman studies

CommunityUsers who inject report occasional mild tiredness. It wasn’t reported in the small topical studies (13–86 people, mostly 8–12 weeks); injection hasn’t been studied in people.

BPC-157Preclinical

CommunityUsers report occasional tiredness. It wasn’t reported in the small human studies (about 80 people, one dose to 2 weeks of use), which gave few safety details.

CJC-1295 (no DAC)Preclinical

CommunityUsers report mild tiredness. No study has given this exact peptide to people, so how often it happens is unknown.

SLU-PP-332Preclinical

CommunityUsers report passing tiredness or a flu-like feeling in the first week or two. No study has checked.

TB-500Preclinical

CommunityUsers report tiredness or lethargy in the first 1–2 weeks of loading. No study has given TB-500 to a person, so it has never been measured.

Studied in people, not reported 18

Labels or trials covered enough people and didn’t report it. It can still happen.

DSIPApproved drug

Not reportedNot listed in the Deltaran label, which says it doesn’t affect driving, or reported in the IV trials; in small insomnia trials daytime alertness improved.

GlutathioneApproved drug

Not reportedNot listed in the Italian label, and not more common than on placebo in IV trials such as a 4-week study of 21 people with Parkinson’s.

GonadorelinApproved drug

Not reportedNot listed in the UK label, which covers a single diagnostic dose. Small pump studies lasting months mainly reported allergic reactions at the infusion site.

SelankApproved drug

Not reportedNot listed in the Russian label. In a 62-person trial it eased fatigue, and added to phenazepam it reduced that drug’s sedation and weakness.

SemaxApproved drug

Not reportedNot listed in the Russian labels or reported in the small Russian trials (27–187 patients, mostly 10-day courses), whose abstracts give few safety details.

SS-31Approved drug

Not reportedNot a listed side effect. In MMPOWER-3 (218 adults, 24 weeks), fatigue scores ended no different from placebo.

TesamorelinApproved drug

Not reportedNot listed as a side effect in the label’s 26-week trials, in which 543 people with HIV took tesamorelin.

ThymalinApproved drug

Not reportedNot listed in the Russian label, which names only allergic reactions; published trials, mostly small and from Russia, gave few safety details.

VIPApproved drug

Not reportedNot listed in Invicorp’s label. In a 196-person trial of 3-day IV infusions, no side effect type except diarrhea was more common than on placebo.

ArgirelineHuman studies

Not reportedNot reported in the small skin trials (up to 60 people, mostly 4–8 weeks); the most reliable lab tests found almost none reaches deeper skin.

CJC-1295 with DACHuman studies

Not reportedTiredness isn’t among the side effects FDA summarized from the published trials (63 healthy adults, up to 49 days).

GHRP-6Human studies

Not reportedNot reported in single-dose studies, including a 250-person diagnostic study that found no side effects. Repeated use hasn’t been studied.

HexarelinHuman studies

Not reportedNot reported: 60 children and young people had no side effects after one IV dose, and studies of up to 16 weeks gave few safety details.

IpamorelinHuman studies

Not reportedNot among the side effects reported from the IV studies (40 healthy men, one dose; 56 surgery patients, up to 7 days).

LL-37Human studies

Not reportedNot among the side effects reported in the ulcer trials (about 200 people, up to 13 weeks), which applied it to wounds. Injected use hasn’t been studied.

MatrixylHuman studies

Not reportedNot reported in the skin trials (93 women for 12 weeks; 196 using a mix for 8 weeks), where it was well tolerated.

SNAP-8Human studies

Not reportedNot reported in two small patch studies that mixed it with other actives (24 people for 28 days; another for 12 weeks); SNAP-8 alone hasn’t been studied.

TesofensineHuman studies

Not reportedNot among the most common side effects in the 24-week obesity trial of 203 adults or the 14-week trial in early Parkinson’s.

No human safety data 18

No one has been given it in a published study, so it can’t be ruled in or out.

DihexaHuman studies

No dataNo human data for dihexa itself. It wasn’t among side effects seen in 4% or more of people taking its injected prodrug for 26 weeks.

5-Amino-1MQPreclinical

No dataNo human safety data: no published study has given it to a person.

AdamaxPreclinical

No dataNo human or animal safety data; Adamax has never been studied.

AHK-CuPreclinical

No dataNo human safety data: AHK-Cu has never been tested in people, on the skin or by injection.

CartalaxPreclinical

No dataNo human data: no study of cartalax in people has been published, so side effects are unknown.

EpithalonPreclinical

No dataNo human safety data: FDA found no study that assessed safety, and its one placebo-controlled trial (40 women, 20-day spray) didn’t report side effects.

Follistatin-344Preclinical

No dataNo human data for injected follistatin; tiredness wasn’t reported in the muscle gene-therapy trials (18 people in two trials).

FOXO4-DRIPreclinical

No dataNo human data: no one has been given FOXO4-DRI in a published study, so side effects are unknown.

HGH Fragment 176-191Preclinical

No dataNo human safety data: this peptide has never been given to a person in a published study.

HumaninPreclinical

No dataNo human data: no one has been given humanin or its stronger version HNG in a published study, so side effects are unknown.

IGF-1 DESPreclinical

No dataNo human safety data exist for IGF-1 DES.

IGF-1 LR3Preclinical

No dataNo human safety data exist for IGF-1 LR3.

KPVPreclinical

No dataNo human safety data: FDA’s 2026 review found no study and no adverse-event report for KPV by any route.

MGFPreclinical

No dataNo human safety data: no published study has given MGF to a person, and FDA’s public adverse-event data hold no reports naming it.

MOTS-cPreclinical

No dataNo human safety data for MOTS-c itself. In a 4-week trial of a modified version, CB4211, injection-site reactions were the only side effect in over 10% of the 11 treated.

PE-22-28Preclinical

No dataNo human data: PE-22-28 has never been given to a person in a study.

PEG-MGFPreclinical

No dataNo human safety data: FDA found no human exposure data for PEG-MGF by any route, and no animal study has been published.

PinealonPreclinical

No dataNo useful human safety data: the few small Russian reports on pinealon gave no details of side effects.

Sources

Each answer comes from the compound’s own page, under “Can it cause …?”, where its sources are listed.