Weight loss jabs and hair loss: what causes it and how to protect your hair

Weight-loss medication can have very visible effects, but not all of them are welcome. Rapid weight loss can lead to facial sagging, wrinkling and hollowing, and is also linked to equally undesirable hair shedding and thinning.

‘I’ve never been so busy since the GLP-1 boom,’ says leading trichologist Mark Blake. ‘Losing weight very quickly from using medications such as Wegovy, Ozempic and Mounjaro has led to a wave of hair loss. Of course that really affects women’s confidence.’

The hair issues he’s seeing aren’t caused directly by GLP-1 drugs themselves, he explains, but due to patients on medication losing their appetite and consequently their hair. ‘Hair isn’t essential for survival, so when you’re not getting enough nourishment, the body will divert energy to things like the heart, the lungs, the kidneys and everything to keep you alive,’ he says. ‘The hair takes the brunt of that. Not everyone on GLP-1s is affected, but I’d say the majority are.'

Rapid weight loss can cause the hair to suffer

He adds, ‘The hair follicle is a prolific user of energy. You need around 160 calories to grow just one gram of hair. So when you’re on these medications, you might make this skinny, thin hair, but you’re potentially not eating enough to grow good-quality hair.’

Then there's shedding. 'Hair likes everything to stay the same', says Mark, ‘and when you change anything, the hair follicles have a little tizzy fit and does do a bit of “spitting out” or what we call telogen effluvium.’

This natural stress response generally shows in the form of accelerated hair shedding a few months after the initial trigger. Hence, hair loss doesn’t begin immediately after commencing GLP-1 medication. ‘Say you started on GLP-1s in January, you would probably start noticing hair loss in about March,’ says Mark.

It’s important to know two things about telogen effluvium: it’s not just a tap you can turn off, but it is temporary in most cases.

‘Hair takes time to adapt, so don’t panic unnecessarily if you start doing the right things and you don’t notice a difference. If you reached your target weight in April and stopped taking GLP-1s, you could carry on losing hair from telogen effluvium all the way up until December. That’s perfectly normal.’

(The situation becomes more complex when telogen effluvium is occurring alongside female pattern hair thinning, a separate issue unrelated to weight loss or GLP-1s. We’ll come to that shortly.)

If you’re planning to take weight-loss drugs, Mark’s advice is to not wait until hair problems begin but to take preventative action. ‘You’ll be consuming fewer calories so it may be impossible to completely avoid the effect of that on your hair, but there are ways to help minimise the impact,’ he says.

Here, he shares his advice on everything you need to know before, during and after taking GLP-1 drugs to protect your hair growth.

This holds true wherever you are in your GLP-1 journey. ‘From what my female patients tell me, many don’t eat breakfast consistently anyway, and even less so when they’re taking GLP-1 drugs and don’t fancy eating,’ says Mark. ‘Breakfast is the most important meal of the day for hair growth. Your liver can store energy for about four or five hours, and after that time, it starts diverting away from the hair.’

It’s true. Breakfast is important.

In other words, your hair is already starving by the time you wake up, says Mark, ‘and if you don’t feed it first thing, it’s going even longer without the nutrition it needs for growth. ‘Hungry’ hair is more vulnerable to thinning and shedding, so even if you don’t feel like eating breakfast, I strongly advise you to do so, for the health of your hair.’

When you’re eating less, you need to make those nutrients count, and what you eat is as important as when. ‘Hair is about 85% protein, and it doesn’t take a genius to work it out that you've got to eat protein for healthy hair growth,’ says Mark. ‘The best thing you can do for your hair, in terms of diet, is to eat some good quality protein, like eggs, at breakfast. Even if you don’t really feel like it, due to GLP-1 drugs, you need to do it.’

It’s likely that your hair will sulk to some extent if you drastically cut calories, ‘but if you can add a bit of protein into the diet you’re eating, you’re less likely to suffer the full impact of it,’ says Mark.

Another important way to buffer the impact of GLP-1 drugs is to ensure you’re getting enough vitamin D. ‘Vitamin D helps hair cell differentiation, and that's the process that pumps hair out of your head,' says Mark.

'If you have low vitamin D levels, it stops that cell-splitting from happening effectively. It’s easy to fix with a vitamin D supplement, but remember it’s a fat-soluble vitamin, so don’t take without food. Vitamin D3 is the best form, and you also have a better absorption rate if you use a spray rather than a tablet. Your body can also use it better if you take it alongside vitamin K2.’

Mark is an advocate for an active called sandalore, which he describes as ‘catnip for hair follicles’ and an excellent way to protect hair growth against hair loss. ‘The hair follicles love sandalore, they go into a growing frenzy, and they also keep the hair in the growing phase for longer,’ he explains. ‘It’s in Nioxin’s Hair Fall Defence Serum, and I’d recommend people get on it before even starting GLP-1 drugs because hair takes time to respond to treatment, and taking that ‘prejuvenation’ approach helps you get the stars aligned in advance.’

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It’s a good idea to get your nutrient status checked via a trichologist, ideally ahead of taking GLP-1 drugs but definitely afterwards if you’re seeing hair loss. ‘We can look at things like their iron storage, which is essentially the petrol you have in your tank. If you’re running low, you can’t generate healthy hair growth. Vitamin B12 is important, too,’ says Mark. ‘Knowing your nutrient status helps you make the right choices to rebalance what you’re missing for optimum hair growth.’

It’s worth investing in a serum

Mark says that ‘everyone’ he sees has heard they should be taking biotin for their hair – a view he vehemently disagrees with. ‘Biotin will do nothing for your hair. I have never seen a patient in all my years who’s been deficient in biotin. But everybody puts it in hair tablets because everybody’s obsessed with it, and you’re more likely to sell a tablet if it has biotin. It won’t do you any harm, but you need so little of it, you’re very unlikely to be deficient in biotin.’

Getting enough sleep, drinking enough water, and exercising regularly are all helpful for healthy hair growth, says Mark. ‘Sex is also great for hair growth because it pumps the blood around your body.’

Check your lifestyle habits

Scalp massage is ‘really good’, in Mark’s view, and a very simple thing to do. ‘All you have to do is place your fingers on the top of your head and just rub your scalp while you’re watching TV. That’s a great thing for getting more blood to the surface.’

As mentioned earlier, telogen effluvium can occur alongside female pattern hair thinning. ‘The latter isn’t caused by weight loss, but if you’re taking GLP-1s, it might be more noticeable sooner if you’re shedding more hair from telogen effluvium,’ says Mark.

If you’re seeing your hair suffering while using weight loss jabs, knowing the underlying causes gives you the best chance of success. ‘If it’s just telogen effluvium, people can expect good results in six months, maybe sooner, but I don't want to give anyone false hope,’ says Mark. ‘It’s often the case that patients have two issues at once, and you want to get the full picture.’

Get a professional to assess your hair

A hair professional will help you work out what’s going on, and give tailored advice, but there are clues to look out for yourself. ‘With telogen effluvium you'll tend to get some short, spiky regrowth, but with female pattern hair loss you get what we call miniaturised hairs, which are ones that are becoming visibly thinner and finer,’ says Mark.

This over-the-counter medication is the gold standard for hair regrowth. It’s particularly valuable for female pattern hair loss, ‘which occurs when follicles become sensitive to something called 5-alpha reductase type 2, leading to miniaturisation,’ says Mark.

‘Minoxidil “numbs” your hair follicles to 5-alpha reductase type 2 so they can’t feel it, and they’ll happily grow hair. That makes it very useful for female pattern hair loss, but it can also help with telogen effluvium because it keeps hair in the growing phase longer, and it’s less likely to shed. So it can be helpful for clients taking GLP-1s, although you can’t use it if you have high blood pressure or heart issues.’