Surgery, anaesthesia and hair: what to expect

Many people notice, weeks after an operation, that hair starts to fall out in larger amounts on the pillow, in the shower or on the brush. Suspicion almost always falls on the anaesthesia. The evidence points in another direction: there is no proof that anaesthetics, in themselves, make hair fall out. What often happens is that the body reacts to the surgery as a whole (the physical stress, blood loss, fever, fasting, some medicines and recovery) with a telogen effluvium, a diffuse, temporary hair loss that appears two to three months later.

There is also a second situation, much less common and almost always forgotten: pressure alopecia, a well-defined patch of hair loss, usually at the nape, caused by the weight of the head resting in the same position for hours. In most cases the hair grows back, but there are rare cases of permanent loss.

In this article we explain how to tell the two apart, which operations carry more risk, what you can do before and after surgery and when to seek assessment.

Two types of hair loss after surgery

Almost all hair loss linked to an operation fits one of two pictures. Telling them apart is the first step, because the prognosis and what is done are different.

Telogen effluvium: the hair loss that arrives late

Each hair lives in cycles. Under normal conditions, about 85 to 90% of follicles are growing (anagen phase) and the rest are resting (telogen phase) before the hair falls out. An intense physiological shock, such as major surgery, can push many follicles into rest all at once. Because the telogen phase lasts about three months, hair loss is only really noticed much later, when the person already feels recovered and rarely links the two.

It is the same mechanism as after childbirth, high fever or rapid weight loss, and it is explained in detail in Hair loss after an illness: what is known. Effluvium does not destroy the follicles: the new hair is already growing when the old one falls out.

Pressure alopecia: the patch on the nape

During general anaesthesia, the head stays still and all its weight rests on a small area of the scalp, usually at the back. If the pressure continues for hours, blood circulates poorly in that area and the follicles suffer ischaemic injury, similar to the beginning of a pressure ulcer. It was first described in 1960 and, since then, there have been reports after cardiac, gynaecological, abdominal and facial surgery, in children and adults, and after long stays in intensive care (Davies and Yesudian, 2012).

Does anaesthesia make hair fall out?

It is the most searched question on the subject, and the short answer is: there is no evidence that anaesthetic drugs, on their own, cause hair loss. There are no studies showing a direct toxic effect of the usual anaesthetics on the follicle.

Anaesthesia enters the story indirectly, in two ways:

• Because of immobility. A person under general anaesthesia does not move their head. It is this immobility, and not the drug, that allows pressure alopecia to develop.
• Because of the conditions during surgery. Low blood pressure, low body temperature and positions with the head lower than the body (the Trendelenburg position) reduce blood flow to the scalp and are described risk factors for pressure alopecia.

In telogen effluvium, the "trigger" is the combined assault on the body: tissue injury and the inflammatory response, blood loss, possible fever or infection, days of fasting or little food, pain and interrupted sleep. Some medicines used around surgery can also contribute, such as anticoagulants (for example, heparin) or beta-blockers, although the association is weak and varies from person to person.

So a local anaesthetic for a minor procedure is rarely associated with hair loss, whereas a long operation with a prolonged hospital stay is associated with it far more often. What matters is the size of the "shock", not the type of anaesthetic.

Pressure alopecia: risk, signs and prognosis

Who is at higher risk

The factors described in the literature repeat from study to study:

• Duration of surgery. This is the most consistent factor. In a trial in cardiac surgery patients, the duration of the operation was a significant risk factor in multivariate analysis. Even so, a 2026 case series in robotic gynaecological surgery described patches even in operations lasting less than four hours (Dhansura et al., 2026).
• Head unable to move. In robotic pelvic surgery, once the robot's arms are docked, it is no longer possible to reposition the head.
• Steep Trendelenburg position (head lower), which favours scalp oedema.
• Low blood pressure, hypothermia and extracorporeal circulation (cardiac surgery).
• Prolonged stay in intensive care, especially with sedation.
• Patient-related factors: little subcutaneous fat on the scalp, advanced age, low albumin and use of corticosteroids.

How to recognise it

The typical picture is an oval or round area on the nape, with clear edges. In the first days there may be swelling, tenderness, redness, blisters or a crust; in other cases, the only thing noticed is the patch, between the first and fourth week. By its shape, it is often mistaken for alopecia areata, which is why a history of recent surgery is important information to give the doctor (on alopecia areata, see Alopecia areata).

Prognosis

In most published cases, hair grows back within weeks to a few months, which suggests a reversible ischaemic injury. In the 2026 series, all six patients recovered fully. When the pressure was intense enough to cause an ulcer, scarring may form and the loss may become permanent, as in the case described by Chang et al., 2016, after a 12-hour operation. Signs that suggest scarring progression: smooth, shiny skin without follicular openings, a wound or crust that is slow to heal, and no regrowth after six months.

Can it be prevented?

Yes, largely, and prevention lies with the surgical and nursing team. The proposed measures include:

• reposition the head at regular intervals, when the surgery allows it;
• use gel or viscoelastic head supports, rather than rigid ring-shaped ones;
• limit the angle and time in Trendelenburg;
• keep blood pressure and temperature stable.

In a trial in cardiac surgery, an alternating-pressure pad (which changes the points of support every 30 minutes) reduced significant hair loss, assessed by the pull test, from 60% to 8.3% and pressure ulcers from 15% to 1.7%, compared with a gel pad repositioned every hour. It was a single-centre study, but it shows that the way the head is supported makes a difference.

Operations more likely to affect the hair

Bariatric surgery

It is the operation most associated with hair loss, for reasons that add up: the surgical shock, very rapid weight loss in the first months, reduced protein intake and, especially in techniques that bypass part of the intestine (such as gastric bypass), poorer absorption of iron, zinc and vitamin B12. Hair loss usually appears between the 3rd and 6th month and is very common in published reviews. In most cases it is a telogen effluvium that recovers once weight stabilises and nutrition is assured. Taking the prescribed supplements and attending follow-up tests is the best protection. On weight loss and hair, see also Losing weight without losing hair: protein and nutrients and Protein, iron and zinc: what your hair needs.

Heart surgery

It combines several risk factors: long operations, extracorporeal circulation, controlled hypothermia, periods of low blood pressure and, often, days in intensive care. It is one of the operations with the most described cases of pressure alopecia, as well as telogen effluvium.

Long operations and robotic or laparoscopic pelvic surgery

Any operation lasting several hours with the head immobile increases the risk of pressure alopecia. In robotic gynaecological and urological surgery, there is also the steep tilt of the table and the impossibility of moving the head during the procedure.

Operations with significant blood loss

Significant bleeding or post-operative anaemia lowers iron reserves (ferritin). Iron deficiency is not the main cause of effluvium, but it can prolong it or make recovery harder. That is why it is worth confirming ferritin in the following months, as directed by the doctor.

Operations requiring a long hospital stay

Complications, infections, fever and many days in bed, with little food, increase the likelihood of effluvium. In these cases, the hair loss reflects a demanding recovery, not a new problem with the hair.

Before surgery: what you can do

It is not possible to guarantee there will be no hair loss, but some measures reduce the risk or help to recover faster:

• Arrive with your reserves in order. If the surgery is planned, ask your doctor whether it makes sense to check haemoglobin and ferritin beforehand. Many hospitals already do this in patient blood management programmes, because pre-operative anaemia also worsens general recovery.
• Eat enough protein in the weeks beforehand, especially before bariatric surgery or if you are on a restrictive diet.
• Raise the subject at the anaesthesia consultation. If you have had pressure alopecia in a previous operation, or if the planned operation is long, it is legitimate to ask how the head will be supported and protected.
• Wear your hair loose and without clips, hair ties or braids. A ponytail or a clip at the nape creates an extra pressure point for hours. Also take out clip-in extensions.
• Do not give your hair aggressive treatments in the days beforehand, such as bleaching or straightening, so as not to add damage to the hair shaft at a time when the hair may become more fragile.
• Gather the list of your medicines and supplements. It helps the team and, later, whoever assesses any hair loss.

After surgery: timeline and recovery

What really helps

• Eat enough, with protein at every meal. Healing consumes protein and energy, and hair is not a priority for the body.
• Correct confirmed deficiencies. Low iron, vitamin D or B12 should be corrected, but on the basis of blood tests: supplements taken without a deficiency do not speed up recovery and some, such as excess vitamin A or selenium, can even cause hair loss. See Blood tests for hair loss: what to ask for.
• Look after your sleep and get moving again as advised by your doctor.
• Treat your hair gently: gentle shampoo, no tight hairstyles and no strong chemicals for a few months.
• Do not stop washing your hair out of fear. Washing does not make hair fall out that was not going to fall; it only gathers, on one occasion, the hairs that were already loose.

Telogen effluvium does not usually need specific treatment. When it lasts more than six months, or when it reveals an androgenetic alopecia that was already there and discreet, the doctor may discuss other options. For the recovery period in general, see Recovering calmly: what helps the body and the hair.

When you should ask for an assessment

At Luxmed, the Hair Medicine consultation includes a detailed clinical history (with the timeline of the surgery), examination of the scalp and trichoscopy, which helps to distinguish effluvium, pressure alopecia, alopecia areata and signs of scarring. When indicated, we request the appropriate blood tests and agree a follow-up plan.

This article is for information purposes and does not replace a medical consultation. The results of any treatment vary from person to person.

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