Collagen for hair: does it help hair growth? What the studies say

Short answer: collagen will not thicken your hair overnight, but the first human studies are interesting. In a placebo-controlled trial with 114 women, hair diameter increased after 24 weeks of low-molecular-weight fish collagen peptides (Hwang et al., 2026). There are still few studies, though, and many tested combination products. Hair is also not made of collagen, so diet, health and patience matter too: it only makes sense to judge the result after several months.

The hair shaft is made of keratin, not collagen. Hair keratin is rich in the amino acid cysteine, which collagen contains only in traces, so collagen is not a direct building block of hair, as is often claimed. Collagen is, however, the main protein of the skin in which hair follicles sit, and the connective tissue sheath around each follicle is largely made of it. Research therefore asks whether collagen peptides from food can influence the environment in which hair grows.

In short: collagen is an interesting direction of hair research, not a proven treatment. Anyone promising thicker hair in a few weeks is promising more than the studies have shown.

Hair grows slowly, and the studies above assessed results after 12 to 24 weeks. Judging the result earlier than after three months of regular use makes little sense. Compare photos taken in the same light and from the same angle; the feeling from your hairbrush can mislead.

Enough protein in your food and enough micronutrients matter for hair growth. A review by Almohanna et al. (2019) sums up that deficiencies of iron, zinc, vitamin D and other nutrients may be linked to hair loss, and that supplementing makes sense mainly where a deficiency really exists.

In the EU, biotin, zinc and selenium carry an approved claim that they contribute to the maintenance of normal hair (Regulation 432/2012). collalloc collagen does not contain them, but a varied diet does: eggs, meat, fish, nuts, pulses and wholegrain bread.

Collagen in shampoos and conditioners stays on the surface of the hair. It can smooth it and add shine for a while, but it does not reach the hair follicle. The studies in the table above looked at collagen taken by mouth.

Increased hair shedding often starts 3 to 4 months after a strain on the body, such as giving birth, an illness with fever, rapid weight loss or stress. The medical term is telogen effluvium (Malkud, 2015). It often settles with time, but it is worth checking the cause. We also cover hair loss after giving birth in Collagen during pregnancy and breastfeeding.

See a doctor or dermatologist if heavy shedding lasts longer than a few months, bald patches appear, your scalp itches or is red, or you have other symptoms such as tiredness or weight changes. Your doctor can check, for example, your iron levels or thyroid.

1. Every day. One serving as stated on the pack; for collalloc that is one sachet (3.3 g).
2. In a cold or lukewarm drink, at most 60 °C. Water, juice, milk or a smoothie.
3. For at least three months. Only then is it worth comparing photos.
4. Alongside a varied diet. Collagen does not replace protein or micronutrients from food.

collalloc collagen is hydrolysed marine collagen with a molecular weight of around 500 Da, with no sweeteners, colourings or flavourings. If you prefer not to mix anything, there is the liquid NANO 2.0 with vitamin C, which contributes to normal collagen formation for the normal function of skin. You will find an overview of collagen for hair and how to take it on our Collagen for hair page, and general advice in How to take collagen.