You're finally feeling a bit better after the flu, and then you suddenly notice it: extra hair on your pillow, in the shower drain, on your sweater. That can be quite a shock. Fortunately, in many cases this is temporary and easily explained. In this blog, we explain how the flu can affect your hair cycle and what you can do to support your hair and scalp as best as possible during this phase.
You're finally feeling a bit better after the flu, and then you suddenly notice it: extra hair on your pillow, in the shower drain, on your sweater. That can be quite a shock. Fortunately, in many cases this is temporary and easily explained. In this blog, we explain how the flu can affect your hair cycle and what you can do to support your hair and scalp as best as possible during this phase.
For many people, flu (especially with a fever) can cause the body to temporarily shift its ‘priorities’: energy is directed towards recovery and the immune system. Hair is less important to the body during such a period. As a result, more hairs than normal can enter a resting phase, resulting in extra hair loss. This is usually diffuse: spread across the scalp, without any obvious bald patches. A similar pattern can also occur with hair loss after COVID-19, where the body temporarily sheds extra hair after a period of severe illness.
Your hair grows in phases. Normally, most of your hair is in the growth phase (anagen). When faced with a significant physical stressor (such as flu with fever), your body can push more hair follicles into the resting phase (telogen) at an accelerated rate. This is called telogen effluvium: a temporary form of hair loss caused by a disruption in the hair cycle.
Important to know: the hair loss often does not occur immediately. You usually notice it weeks or months later, because hairs first “come loose” after they have entered the resting phase.
You usually notice it 6 to 12 weeks after the illness/fever. This corresponds to what is often described in cases of hair loss after fever, where hair loss is regularly seen around 9 weeks after a period of fever.
This is also exactly why it sometimes feels like it comes out of nowhere: you have been better for a long time, but your hair cycle is lagging behind.
In many cases, your hair growth cycle will recover on its own. Hair loss after illness/fever often takes months to recover, with noticeable improvement around 6–9 months. That doesn't mean you'll continue to lose hair at the same rate throughout that time. Usually, it builds up, peaks for a period, and then subsides again.
Fever and infection put pressure on the body. This can cause stress hormones (such as cortisol) to rise, which can affect the hair cycle and push hair into the resting phase.
When you are ill, you often eat less, while your body actually needs a lot of nutrients to recover. Deficiencies (e.g. iron, zinc, vitamin D or B12) can increase hair loss or slow down recovery.
Some medicines can also affect the hair cycle. Hair loss due to medication often occurs with a delay, for example 2 to 4 months after starting. This is similar to the timing we see with telogen effluvium.
Hair loss after flu usually manifests as diffuse loss (thinning all over). If you notice round/patchy bald spots, there may be something else going on, such as alopecia areata (an autoimmune reaction). This is a different type of hair loss and often requires a different approach or medical assessment. If you are unsure, it is wise to consult a specialist.
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When it comes to hair loss after the flu, it's all about resting the scalp, supporting the hair roots and restoring from within. The products we recommend during this phase are:
The Trichological Society. (n.d.). Hair loss due to fever. Retrieved on 17 February 2026, from https://www.hairscientists.org/hair-loss-due-to-fever
