GHK-Cu user experiences: what users themselves report
Users’ own accounts, not research. The accounts are self-selected and prove neither that it works nor that it is safe.
This page does not list users’ doses or sellers, and no figure on it is a recommendation. Doses used in studies, with sources: GHK-Cu dosage in studies.
In short
Of 743 people, 369 (50%) said GHK-Cu brought some benefit and 401 (54%) some harm.
We went through 1,747 public Reddit posts and a random sample of comments (1,500); the first-hand experiences of 743 users among them are compiled here. Method: Where the accounts come from and how we read them. Use of AI: AI disclosure.
- An AI model read and classified 1,747 public Reddit posts and 1,500 randomly chosen comments one by one, following written instructions. Leaving out posts that looked like marketing, 896 were first-hand accounts, from 743 different people.
- Benefits mentioned most often: skin quality, firmness or fine lines (143, 19%), less pain or inflammation (62, 8%) and hair growth or thickness (60, 8%).
- Harms mentioned most often: injection site pain, redness or lump (212, 29%), breakouts or purging (29, 4%) and fatigue (28, 4%). In addition, 137 (18%) described some other, rarer harm. People tend to post when something goes wrong, so this share does not tell how common harms are.
- Comments reported benefit only clearly more often than posts (50% vs. 30%) and harms less often (39% vs. 64%). A possible reason is that people tend to post when something goes wrong: Posts vs. comments.
- Most of those who said how they used it had injected GHK-Cu (383 people), so the figures in practice describe injections. Only 50 applied it to the skin, and some of them also injected, so the figures say little about creams and serums.
- The accounts cannot separate the substance from placebo or other causes. What the research shows: GHK-Cu: what the research shows.
Where the accounts come from and how we read them
Sources: the Reddit forums r/Peptides (543 accounts), r/Biohackers (236), r/bpc_157 (74), r/Retatrutide (14), r/tretinoin (12), r/Nootropics (5), r/Melanotan2 (5), r/NMN (3), r/glutathione (2), r/TB500 (1) and r/mk677 (1), 14 Oct 2024 to 12 Oct 2026. The posts were retrieved from a public Reddit archive. 4,124 posts matched the search, and 3,000 of them were taken at random. Of those, 1,747 were first-person posts about GHK-Cu, and every one was read. In addition, 9,113 comments met the same criteria in the same period (two years, 13 Oct 2024 to 13 Oct 2026), and a random 1,500 of them were read. The sample was drawn with a fixed seed, so it can be repeated.
Coding: for each account we recorded the route, reported benefits and harms, how strong a harm was, whether and why the person stopped, length of use and other substances used at the same time. We kept accounts that reported some effect, some harm, or no effect. Questions and plans were left out. A harm was recorded when the person reported it during use, even if the cause was uncertain. Several posts by one person count as one person. One person can mention several things, so the shares in the tables do not add up to 100.
Check: an AI model read and classified the posts following written instructions. A second, separate AI run classified a random tenth (175 posts) again without seeing the first classification. The main fields matched: 171/175 (98%). 150 of the comments were re-classified the same way, and the main fields matched: 148/150 (99%). 11 posts looked like marketing and are not in the figures.
Whose accounts these are: routes mentioned: injection 373, on the skin 33, injection and on the skin 18, by mouth 5; the others did not say. The figures describe the writers and are not a recommendation. The products were not verified, so we do not know what people actually took.
Did GHK-Cu help? The overall picture
Of 743 people, 278 (37%) reported benefit only, 91 (12%) both benefit and harm, 310 (42%) harm only and 64 (9%) neither.
Stopping. 81 people (11%) said they stopped or paused: 68 because of harms and 13 because they noticed no effect or for another reason.
| Overall picture: benefit, harm or neither | People | Share |
|---|---|---|
| Benefit only | 278 | 37% |
| Both benefit and harm | 91 | 12% |
| Harm only | 310 | 42% |
| Neither benefit nor harm | 64 | 9% |
Posts vs. comments
The figures on this page combine two sets: all 442 people who described their own use in a post, and 301 people found only in comments. 9,113 comments met the criteria, and a random 1,500 of them were read, from the same period as the posts: two years, 13 Oct 2024 to 13 Oct 2026. Because only part of the comments was read, the combined shares are not an average of the whole discussion.
Comments reported benefit only clearly more often, and harms less often, than posts. Benefit only: 30% in posts and 50% in comments (difference +20 percentage points, 95% confidence interval +12 to +27). Some harm: 64% in posts and 39% in comments (difference -25 percentage points, 95% confidence interval -32 to -18).
A possible explanation, which we have not verified: people tend to write their own post when something goes wrong, while replies often say briefly that it worked. Neither group tells how often it really helps or harms, and the difference does not prove that it works.
| Reported | Posts (n = 442) | Comments (n = 301) | Difference, points (95% CI) | Clear difference? |
|---|---|---|---|---|
| Benefit only | 30% (132) | 50% (149) | +20 (+12, +27) | Yes |
| Some harm | 64% (282) | 39% (116) | -25 (-32, -18) | Yes |
Most common reported benefits
Of 743 people. 369 (50%) mentioned some benefit; the table lists every benefit reported.
| Reported | People | Share |
|---|---|---|
| Skin quality, firmness or fine lines | 143 | 19% |
| Less pain or inflammation | 62 | 8% |
| Hair growth or thickness | 60 | 8% |
| Healing of wounds or injuries | 57 | 8% |
| Energy or wellbeing | 35 | 5% |
| Skin glow or tone | 32 | 4% |
| Scars or marks | 24 | 3% |
| Less acne | 13 | 2% |
| Under-eye area | 8 | 1% |
| Other benefit | 145 | 20% |
Share = people / 743.
Most common reported harms
Of 743 people. 401 (54%) mentioned some harm; 47 said explicitly they had none.
| Reported | People | Share |
|---|---|---|
| Injection site pain, redness or lump | 212 | 29% |
| Breakouts or purging | 29 | 4% |
| Fatigue | 28 | 4% |
| Allergic reaction or hives | 26 | 3% |
| Mood or anxiety | 22 | 3% |
| Sleep problems | 18 | 2% |
| Skin darkening or patches | 16 | 2% |
| Nausea | 11 | 1% |
| Dryness or flaking | 8 | 1% |
| Headache | 8 | 1% |
| Skin irritation, redness or stinging (topical) | 5 | 1% |
| Hair shedding | 4 | 1% |
| Metallic taste | 1 | 0% |
| Other, rarer harm | 137 | 18% |
| Harms mentioned but not named | 6 | 1% |
Share = people / 743.
How severe were the harms?
Of the 399 people who described how strong a harm was, 249 (62%) described it as mild, 135 (34%) as clearly bothersome and 15 (4%) as severe. The strength is the writer's own description, not a doctor's assessment.
| Strength of the harm as the writer described it | People | Share |
|---|---|---|
| Mild: minor and manageable | 249 | 62% |
| Clearly bothersome: several days, sleep or work affected | 135 | 34% |
| Severe: emergency visit, hospital or unable to function | 15 | 4% |
Harms known from research and regulators: What are the side effects of GHK-Cu?
How long did people use GHK-Cu?
415 of 743 people (56%) said how long they had been using it at the time of writing. Where one person wrote several posts, the longest stated time counts.
| Stated length of use | People | Share |
|---|---|---|
| Under a week | 87 | 21% |
| 1-4 weeks | 125 | 30% |
| 1-3 months | 147 | 35% |
| Over 3 months | 56 | 13% |
Many people post partway through, often in the first days or as soon as harms start, so short times are over-represented. The numbers describe the writers; they do not say how long it should be used.
Other substances at the same time
502 of 743 people (68%) used other substances at the same time. The most common: BPC-157 (318), TB-500 (278) and KPV (145). Then the account cannot tell which substance had the effect.
Injected or applied to the skin?
Of those who said how they used it, 373 described injections, 18 both injections and applying it to the skin, 33 applying it to the skin only and 5 taking it by mouth. The others did not say.
383 people injected it. Of them, 288 (75%) reported some harm and 212 (55%) pain, redness or a lump at the injection site. 128 (33%) reported some benefit.
50 applied it to the skin, and some of them also injected. Of them, 33 (66%) reported some benefit and 19 (38%) some harm. The group is small and mixed with injections, so these figures do not reliably describe creams or serums. Accounts from users of skin creams and serums are compiled separately: user experiences with collagen and skin peptides.
About dosing
We do not repeat the amounts or ways of use people mention, and we give no dosing or how-to instructions. A safe dose is not known. Doses used in studies, with sources: GHK-Cu dosage in studies. Legal status: Is GHK-Cu legal in Finland?
What can be concluded?
The accounts are mostly about injections, and the most common thing reported was an injection-site reaction. They say little about GHK-Cu applied to the skin.
The accounts prove neither that it works nor that it is safe. The writers are self-selected, the product contents are unknown, many used several substances at once, and placebo effects can be large. The research and its evidence levels: GHK-Cu: what the research shows.
Quotes
Short excerpts in the writers’ own words. Writers’ names and links are not shown. We picked quotes from every group: benefit, both benefit and harm, no effect, harms and people who stopped.
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"I have thought over the last few weeks that my skin has become softer and feels more plump, but i wasn't fully sure."
r/Peptides, 2026-05, Route not stated. Used it for five weeks. Reports softer skin, and a friend said unprompted that her skin was glowing.
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"I am a long-time user of GHK-Cu topically with good results"
r/Peptides, 2025-11, On the skin (cream or serum) for a long time with good results. When the writer tried injections, the site became red and swollen.
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"I love the effects on my skin. But the subq injections leave red marks on my lower abdomen or glute for over a week from each pin."
r/Peptides, 2025-05, Injected under the skin. A couple of cycles. Likes the effect on the skin, but every injection leaves a red mark for over a week.
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"I have to say it’s done absolutely nothing. I have no pain when injecting"
r/Peptides, 2025-07, Injected. Duration not stated. No effect at all, and the writer doubts the product quality.
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"There’s a noticeable bump, the skin gets red and warm and once I start itching it I can’t stop."
r/Biohackers, 2026-03, Injected under the skin. The injection site gets an itchy, red, warm welt that darkens and lasts several days.
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"2 weeks. Large knots under the skin. Tried lots of Reddit theories to make it better. Nothing worked, so I gave up."
r/Peptides, 2026-08, Injected. Two weeks, then stopped because of lumps at the injection sites.
Other summaries made with the same method: BPC-157 user experiences, GLOW blend user experiences, KLOW blend user experiences, TB-500 user experiences, KPV user experiences, Melanotan II user experiences, Melanotan 1 user experiences and user experiences with collagen and skin peptides.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.