The best hair growth serums for fuller, healthier-looking hair

Why trust the Good Housekeeping Institute?

We’ve been testing products for over 100 years here at the Good Housekeeping Institute, from the best shampoos and best day creams to, in recent years, the best hair straighteners and LED masks.

Our beauty tester Juliet Heaton led our review of hair growth serums. She has degrees in both chemistry and cosmetic science, so she understands ingredients and how they can be used in formulations to stimulate growth. She also worked with our panel of at-home testers to collate their feedback, analyse the findings and award each product a score based on the criteria that matter.

Our lifestyle writer Madeleine Evans then used both sets of data to help inform her product write-ups. Having experienced hair thinning herself, she knows how much it can impact confidence and the importance of finding a genuinely effective solution.

Can hair serum regrow hair?

A hair serum isn’t a magic bullet, but it can help create the right environment for healthy hair growth. How effective it is will depend on the nature of your hair loss. If you’re experiencing receptive hair loss, such as telogen effluvium (which is triggered by stress, post-partum, or rapid weight loss), then it’s likely that a hair serum will be able to reinvigorate the growth phase of hair follicles.

If you’re experiencing hair loss due to alopecia or pattern baldness, a hair serum won’t work. We always advise speaking to your GP to understand the underlying cause of your hair loss and the right treatment for you.

Are hair growth serums safe to use?

Always consult your doctor before using these serums if you’re unsure, but hair growth serums are generally safe to use for most people. They usually contain nourishing ingredients such as caffeine or peptides but be sure to check the ingredient list if you’re prone to skin flare ups or allergies.

What’s the difference between minoxidil and a serum?

Minoxidil is a prescribed oral tablet taken to combat hair loss, while hair serums are a topical treatment applied directly to the scalp.

“Proven ingredients for hair loss, such as minoxidil medication, work by widening the blood vessels and improving blood flow to your hair follicles, to potentially prolong the growth phase,” says Hannah Gaboardi, trichologist at the Nobu Clinic.

“A scalp serum is a more cosmetic and less invasive way to stimulate the scalp. Serums containing active scalp-soothing ingredients, such as tea tree oil and peppermint, can help soothe scalp irritation, while formulas that contain ingredients such as caffeine help to maintain blood flow to the area. This helps your hair get the vital nutrients needed to promote hair growth and strengthen the follicle,” Hannah adds.

How long do I need to use a hair growth serum before I see results?

“With hair growth serums, changes should start to become more apparent after 12 weeks of use. Visible regrowth and restored density typically take closer to 3-6 months, with more significant changes often seen around the 6-12-month mark, depending on the severity,” says Hannah.

Supplements vs hair growth serums: which is better?

“Nutrients such as protein, iron, zinc, biotin, vitamins A and E, and omega-3 fatty acids are essential for maintaining healthy hair growth, strength and texture,” says Hannah. Note that you should be able to get these through a balanced, healthy diet, but some people may find they need supplements to get enough. “Taking supplements regularly is a great way to keep your hair in the growth phase,” explains Hannah.

“Because hair is a non-essential tissue, the body prioritises vital organs first, meaning nutritional deficiencies often show up in the hair before anywhere else,” she adds.

“A hair growth serum, on the other hand, works directly on the scalp and hair follicles,” Hannah continues. “Depending on their ingredients, they can help stimulate dormant follicles, improve scalp health, reduce inflammation and increase the time hair spends in the growth phase, all encouraging thicker, healthier-looking hair.”

“It’s important to understand whether there are any underlying deficiencies in your diet first,” she advises, “as supplementing can then be used to increase your intake. Correcting this is essential before using serums, as your hair is unable to be in the growth phase if the deficiencies are present.”

What are the best ingredients to look for in a hair growth serum?

When deciding on which hair growth serums to test, our testers scoured ingredient lists, making sure they included those proven to increase growth. These are some of the main ones to look out for.

Caffeine – Not just good for perking you up in the morning, caffeine is also effective at stimulating hair follicle metabolism and extending the hair’s growth phase. It also helps block the hair loss hormone DHT.

Biotin/Vitamin B7 – Aids the production of the protein keratin, which gives hair its structure, reducing breakage and thinning.

Peptides – These also stimulate keratin production, as well as collagen, to help strengthen existing hair follicles and stimulate them to enter into the active growth phase, resulting in additional thickness.

Hydrators – Ingredients such as hyaluronic acid and glycerine help to soothe dry, flaky scalps and create an optimal environment for hair growth.

Do hair growth serums have any side effects?

While most hair growth serums are generally well-tolerated, depending on your skin type and sensitivity, they can have mild side effects, such as scalp tingling and itchiness. If your symptoms worsen, stop using the serum and speak to a GP or trichologist if you have concerns.

What can stimulate hair growth naturally?

There are some factors within our control that can help to minimise hair shedding and breakage, as consultant dermatologist and hair specialist, Dr Sharon Wong, explains.

"Maintaining a well-balanced diet that includes the full spectrum of macro and micronutrients is the best and most sustainable way of supporting healthy hair growth (and a healthy body in general),” she says. “Unless you know you have a vitamin deficiency, hair growth supplements will not have an impact.

“Instead, eat well, minimise the use of heat and dyes, and use the best hydrating hair masks and best heat protectants. Don’t expect a miracle, but doing these things will support the condition of existing hair fibres and optimise the environment for healthy hair growth.”

There are some bad habits you can put a stop to as well. "Smoking has been shown in some studies to be associated with premature balding and greying of hair,” says Dr Wong. “In many people, stress can also be a trigger for hair loss, whether that be shedding or the onset of alopecia areata (an autoimmune hair loss condition).

“Eliminating stress may not be possible, but try to find some coping strategies that equip you with the right mindset to process and handle it more effectively when challenges arise.”

Do hair growth serums actually work?

Our tests have proven that good hair growth serums can make a difference, but you do have to be realistic; you're never going to wake up with a miraculously full head of hair.

"Many hair serums contain peptides/amino acids and conditioning agents such as hyaluronic acid,” explains Dr Wong. “These have an aesthetic effect on the hair that’s already on the head, giving it more volume and plumping up its fibres to make them look and feel thicker. However, this is not the same as growing more hair or thicker hair from the roots.

“These natural compounds may be useful as a preventative measure, but reliable, consistent results for hair thinning are far more likely to be achieved by Minoxidil and other prescription medications from your doctor.”

The verdict on the best hair growth serums

Our winner, the Monpure Hair Density Serum was the top scorer when it came to increasing hair length and thickness over the trial period.

The most affordable option on our list is The INKEY List’s Caffeine Stimulating Scalp Serum, which improved most of our testers’ hair density and length.

If you’re looking to calm an irritated scalp, then trichologist-owned brand, Philip Kingsley’s Density Preserving Scalp Drops helped to calm any itchiness or soreness, while also encouraging new growth.