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Hair loss can be caused by a variety of factors

Professor Ralf Paus identifies four main causes of hair loss. One is that you could have a hormonal imbalance, which affects your follicles by making them smaller or stopping them grow. “You can have inflammatory reasons” continues Ralf, “so that your own immune system starts to attack your hair follicles.” Then there are toxic effects on the hair follicle, “perhaps the most famous of these being chemotherapy-induced hair loss.” Finally, some drugs can be the cause.

Female pattern hair loss is predominantly caused by low oestrogen

Female pattern hair loss is largely caused by hormonal imbalances. The change is likely due to both the activity of male hormones, or androgens, as well as a relative lack of female hormones or oestrogens – explains Ralf. Hair loss can occur frequently after giving birth because oestrogen levels, which are very high during pregnancy, dramatically drop. “The second time when this hair loss gets accelerated and aggravated is during menopause, when the oestrogen levels again slowly fall.” says Ralf.

For this reason, when Ralf was running hair clinics in Germany, he often prescribed women an oestrogen tincture to apply to their. He observed it didn’t promote regrowth of new hair shafts but it kept hair follicles longer in their growth phase. However this treatment isn’t currently available on the NHS or recommended by government guidance, and there isn’t yet good evidence from scientific trials that it works consistently.

Male pattern hair loss is pre-programmed in the womb – but a pill can help

Like female pattern hair loss, male pattern hair loss is down to hormones in particular androgens. Testosterone is a weak androgen, but over time it gets transformed into something much more potent: dihydrotestosterone, or DHT. When hair follicles on the top of the head are stimulated with DHT they produce molecules that prevent hair growth. Strangely, beard hair follicles have the exact opposite reaction and produce molecules that stimulate hair growth instead! “The response of the hair follicles in different regions of your skin, to the same hormone, is completely different.” says Ralf, an effect that “is pre-programmed in foetal life”.

The enzyme inhibitor finasteride, taken as a tablet, works by blocking the conversion of testosterone into DHT, which Ralf says is “a very useful technique for inhibiting the progression of male pattern baldness.” One large clinical study found that it stopped hair loss in 80 to 90% of men. It’s currently only licensed for use in men because of the possibility of side effects in women, especially pregnant women. But Ralf says that for post-menopausal women it may be justified.

There’s another drug, dutasteride and smaller clinical trials show that it is “slightly superior to finasteride in its efficacy”.” But it is unlicensed so Ralf advises medical supervision for this one.

A hair loss drug developed to treat high blood pressure works for some

The active ingredient inside products such as Regaine is minoxidil, which typically comes as a topical solution that’s applied to the scalp. It was actually developed to treat high blood pressure, but one of its side effects was hair growth.

“What minoxidil actually does to our hair follicles is still not clear enough” says Ralf. Studies suggest that more than half of patients that use it twice daily, for at least half a year, will see that their hair loss does not further progress. “The percentage of patients that actually see hair regrowth that they find cosmetically acceptable – that is much lower.” And he says the experience you’ll get isn’t predictable, so you could be one of the relatively few who sees a phenomenal effect, or you could see no effect at all.

Online pharmacies also sell Minoxidil tablets. These can also work but they come with slightly, higher risks of certain adverse effects such as cardiac arrhythmia says Ralf. “Patients that have cardiac problems should only take minoxidil as a topical agent, not as a tablet.”

You need to take the drugs for at least a year to know if they work

“The one critical thing is that patients often give up too early” says Ralf. A lot of studies have shown that even after six months, you can still become a responder to minoxidil. So, his advice is try it for at least a year.

“When you use finasteride, you need to wait even longer to see an effect” he says. “Don't even start it if you're not willing to take it a year.” And it definitely makes sense to combine the two, he says, and use finasteride tablets with the topical minoxidil.

Crucially, “they will only help you as long as you take them – because the general problem that has caused the hair loss has not gone away.”

Caffeine stimulates hair follicles – but not in a shampoo

Laboratory studies in petri dishes show that caffeine “stimulates your hair follicles and makes them more stress resistant” says Ralf – but clinical evidence in humans is still missing.

And ditch the shampoos, says Ralf: “No shampoos will give you any predictable hair growth promoting effects… for the simple reason that the contact time with your scalp skin is far too low.” You need an alcoholic tincture that stays on the skin and can slowly sink in.

Listen to the Sliced Bread episode on caffeine shampoo from 2020 here.

Food supplements can help – but a steak might be better

Our hair follicles are engineered to absorb ingredients from the blood: amino acids and other nutrients, says Ralf. “That means that if you administer the right food supplements, you have at least a chance to impact.”

Forget Biotin (vitamin B7), says Ralf. It’s good for your nails but “there is not very good evidence that it is really very good for your hair shaft production.” Similarly, vitamin D is useful for multiple reasons, but hair growth promotion is not top of the list.

Collagen might help. What you really need is sufficient protein supply, and collagen is a protein. But Ralf says: “There is so far no good evidence that taking just collagen will do much to promote your hair growth. So, you might as well eat a good steak.” (Or nuts and soy, if you’re veggie).

Clinical evidence is still key

In conclusion, the licensed drugs finasteride and minoxidil “are definitely not marketing BS,” says Ralf. But if they do work for you, you’ll need to continue taking them indefinitely.

There are some cosmetic products and food supplements on the market where laboratory evidence suggests their ingredients could do something positive for hair growth. But what we need, in order to make a truly informed decision, is the (largely lacking) clinical evidence.

To find out what products Kimberley and Ian think are worth spending their money on, listen to the episode in full on 麻豆约拍 Sounds.