Blaming your GLP-1 medication for hair loss? You might be asking the wrong question

Globally, more people are using GLP-1 and other weight-loss medicines, and some are experiencing severe hair loss while taking them. But just because it is happening during treatment does not necessarily mean the treatment caused it.

According to Dr Kashmal Kalan, Medical Director at Alvi Armani, “Hair shedding during treatment isn’t always caused by the medicine itself. In many cases, it may be the body’s response to losing weight too quickly. Your body reacts as though food is scarce and thinks: ‘Hair isn't essential. Let's save energy’.” Rapid weight loss can increase the risk of temporary hair shedding, whether it follows GLP-1 treatment, bariatric surgery, a very low-calorie diet, or illness. The trigger is often the speed and extent of the weight loss rather than the treatment itself.

Eating much less can also leave patients short of nutrients that hair needs. “Think of hair like a houseplant. If you don't water it enough with the right nutrients, it grows poorly. It doesn't necessarily die permanently but simply pauses its growth.” The concern is becoming more relevant as weight-loss medicine use grows in South Africa. Discovery Bank and Visa's latest SpendTrend report found that 14% of surveyed higher-income South Africans use prescribed weight-management medication. Clinical research has also found that GLP-1 medicines reduced energy intake on a controlled test day by nearly a quarter compared with placebo, which helps explain why nutritional adequacy may become more important when appetite drops.

The potential causes behind rapid hair loss

Dr Kalan says Alvi Armani is seeing more patients who report sudden hair shedding weeks or months after starting weight loss treatment and assume the medicine is directly responsible. The consultation must then establish when the shedding began, how quickly the patient lost weight, how their eating patterns changed, and whether another medical cause needs to be investigated.

A review of nearly half a million adults on GLP-1 treatment found vitamin D deficiency in 7.5% of patients at six months, climbing to 13.6% by twelve months. That's why bloodwork and not a shopping list of supplements is the first step in any hair loss consultation at Alvi Armani, whether GLP-1-related or not. Standard testing includes vitamin D, B12, ferritin, and thyroid function as standard.

“Ferritin, the protein that stores iron, is one marker I monitor closely. A level below 30 ng/mL, generally considered indicative of low iron stores in adults, is often enough to cause shedding on its own, even though most labs still call that number normal. Most of these patients feel completely fine elsewhere, so there's no reason for a routine GP visit to pick it up. By the time the hair's already falling out, we go back and look for what that visit potentially missed.”

Some patients may also reach for gut-health supplements because they assume hair loss comes from issues in the gut. However, Dr Kalan notes, probiotics will only address the problem if a digestive condition is actually contributing to it. Research remains limited, with the largest randomised trial to date finding reduced shedding among the probiotic group, but no meaningful improvement in hair density or thickness.

“If someone has a diagnosed digestive condition, that's worth treating, and probiotics may have a place. Outside of that, I'd rather see patients pursue tests that can identify what's missing than a supplement with no clear indication, strain, or dose.”

When to take shedding seriously

Dr Kalan encourages anyone on a GLP-1 medication to take shedding seriously if it continues past three months, worsens noticeably, or comes with fatigue or other symptoms that don't add up.

“These medications genuinely change lives for the right patient. If your registered health professional recommends continuation, stay on it. Just make sure your body is still getting what it needs.”