Crohn's disease hair loss is a distressing but often overlooked symptom that affects some people living with this chronic inflammatory bowel condition. Hair shedding in Crohn's disease can result from several interconnected factors, including systemic inflammation, nutritional deficiencies caused by impaired gut absorption, and side effects of certain medications used to manage the condition. Understanding the underlying causes is essential for effective management. This article explains why hair loss occurs in Crohn's disease, which medications may contribute, how nutritional deficiencies play a role, and when to seek advice from your GP or IBD team.

Why Crohn's Disease Can Cause Hair Loss

Crohn's disease causes hair loss primarily through systemic inflammation triggering telogen effluvium, and through impaired gut absorption leading to nutritional deficiencies that affect hair follicle function.

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Hair loss is a recognised but often overlooked symptom experienced by some people living with Crohn's disease. It can be distressing, particularly when it occurs alongside the other physical and emotional challenges of managing a long-term inflammatory bowel condition. Understanding why it happens is an important first step in addressing it effectively.

Crohn's disease is a chronic inflammatory condition that can affect any part of the gastrointestinal tract. The systemic inflammation associated with active disease places significant physiological stress on the body. This stress can trigger a form of hair loss known as telogen effluvium, in which a larger-than-normal proportion of hair follicles prematurely enter the resting (telogen) phase of the hair growth cycle, leading to diffuse shedding. Shedding is typically noticed two to three months after a triggering event such as a disease flare. Once the underlying cause is addressed, shedding usually begins to settle within a few months, though visible regrowth may take three to six months or longer.

Beyond inflammation itself, Crohn's disease can impair the absorption of key nutrients in the gut, particularly when the small intestine is affected. Since hair follicles are among the most metabolically active structures in the body, they are highly sensitive to nutritional shortfalls. Deficiencies in iron, zinc, vitamin D, and B vitamins — all of which are commonly seen in people with Crohn's disease — can independently contribute to hair thinning and shedding.

It is important to note that not all hair loss in people with Crohn's disease is directly caused by the condition. Other common causes — including androgenetic (hereditary) hair loss, postpartum shedding, thyroid disorders, and traction from certain hairstyles — should also be considered. Your GP or IBD team can help identify the most likely cause. The assessment section below outlines when to seek advice.

Finally, the psychological burden of living with a chronic illness, including anxiety and depression, can itself contribute to hair loss. Stress-related telogen effluvium is well documented, and the emotional impact of Crohn's disease should not be underestimated when considering the full picture of hair health in this patient group.

Medications for Crohn's Disease Linked to Hair Thinning

Methotrexate, azathioprine, anti-TNF biologics, and corticosteroids are all associated with hair thinning; medication-related hair loss is often temporary and should be discussed with your IBD team rather than leading to unsupervised treatment changes.

Several medications commonly used to manage Crohn's disease have been associated with hair loss as a side effect. It is important to approach this topic carefully: for most people, the benefit of controlling active inflammation far outweighs the risk of hair thinning, and stopping medication without medical advice can lead to serious disease flares.

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Methotrexate, an immunosuppressant used in some cases of Crohn's disease, is one of the more commonly implicated drugs. It works by inhibiting folate metabolism and rapidly dividing cells — including hair follicle cells — which can result in diffuse hair shedding. This effect is often dose-dependent and may improve with folic acid supplementation, which is routinely prescribed alongside methotrexate in UK clinical practice. The Summary of Product Characteristics (SmPC) for methotrexate, available via the MHRA/EMC, lists alopecia as a recognised adverse effect.

Azathioprine, another immunosuppressant frequently used in Crohn's disease management, has also been reported to cause hair loss in some patients, though this is considered less common. The azathioprine SmPC should be consulted for full adverse effect information.

Biological therapies such as anti-TNF agents (e.g., infliximab and adalimumab) have occasionally been linked to hair changes, including both diffuse hair loss and, in some cases, new-onset alopecia areata — an autoimmune condition affecting the hair follicles. Alopecia is listed in the product information for some biologics; however, the reported frequency varies between agents. Patients and clinicians should refer to the SmPC or European Medicines Agency (EMA) European Public Assessment Report (EPAR) for the specific medicine being used.

Corticosteroids such as prednisolone, used during flares, can also affect hair growth with prolonged use, and may cause changes including hair thinning or, conversely, increased body hair (hirsutism). These effects are generally associated with longer-term or high-dose use.

If you suspect a medicine may be causing or contributing to hair loss, you can report this to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app. Patients should be reassured that:

• Hair loss related to medication is often temporary

• Dose adjustments or alternative agents may be considered by the treating team

• They should never stop prescribed medication without first consulting their IBD team or GP

Nutritional Deficiencies and Their Role in Hair Loss

Iron, zinc, vitamin D, vitamin B12, and folate deficiencies — all common in Crohn's disease due to malabsorption — are significant, modifiable contributors to hair loss that should be identified through routine blood monitoring.

Nutritional deficiency is one of the most significant and modifiable contributors to hair loss in people with Crohn's disease. Because Crohn's can impair nutrient absorption — particularly when the terminal ileum or small bowel is involved — deficiencies are common even in patients who appear to be eating a balanced diet.

Iron deficiency is among the most prevalent nutritional problems in Crohn's disease and a well-established cause of hair loss. Iron is essential for the production of haemoglobin and plays a direct role in supporting hair follicle function. Iron deficiency anaemia can cause diffuse hair thinning. In people with IBD, iron deficiency is typically defined as a serum ferritin below 30 µg/L when there is no active inflammation, or below 100 µg/L in the presence of inflammation (where ferritin may be falsely elevated as an acute-phase reactant); a transferrin saturation (TSAT) below 20% is also used as a marker. These thresholds are outlined in ECCO guidance on anaemia and iron deficiency in IBD and the BSG guideline on management of iron deficiency anaemia in adults (2021). Routine monitoring of full blood count and iron stores is recommended as part of IBD care in the UK, in line with NICE NG129 (Crohn's disease: management) and IBD UK Standards.

Zinc is another critical micronutrient for hair health. It supports protein synthesis and cell division within the hair follicle, and deficiency can lead to hair shedding and changes in hair texture. Zinc deficiency is particularly common in Crohn's disease due to malabsorption and increased gastrointestinal losses. It is important to note that excessive zinc supplementation without medical supervision can cause copper deficiency, so supplementation should always be guided by blood test results and clinician advice.

Other nutrients worth considering include:

• Vitamin D — frequently deficient in people with IBD; low levels have been associated with disruption to hair follicle cycling, though the evidence for a direct causal link to hair loss remains associative rather than definitive

• Vitamin B12 — absorption is dependent on the terminal ileum, which is commonly affected in Crohn's disease

• Folate — particularly relevant in patients taking methotrexate

• Protein — inadequate intake or absorption can impair hair structure and growth

High-dose biotin (vitamin B7) supplements, sometimes marketed for hair health, should be used with caution: the MHRA has highlighted that high-dose biotin can interfere with certain laboratory assays, potentially affecting test results. Always inform your healthcare team of any supplements you are taking.

Routine nutritional screening is recommended as part of IBD care in the UK, including access to a registered dietitian with IBD experience (IBD UK Standards). If deficiencies are identified, targeted supplementation under medical supervision can help address hair loss alongside broader health outcomes. Self-prescribing high-dose supplements without guidance is not recommended.

When to Speak to Your GP or IBD Team

Seek advice if you experience sudden or significant shedding, patchy hair loss, scalp symptoms, or hair loss accompanied by fatigue or breathlessness, as these warrant clinical assessment and possible dermatology referral.

Hair loss can feel like a deeply personal and sometimes embarrassing concern, and patients may hesitate to raise it during appointments focused on gut symptoms. However, it is a clinically relevant issue that deserves proper assessment, and healthcare professionals are well placed to help identify the underlying cause.

You should contact your GP or IBD team if you notice:

• Sudden or significant hair shedding, particularly in the weeks or months following a disease flare or change in medication

• Patchy hair loss, which may suggest alopecia areata — an autoimmune condition that has been reported in association with IBD; discuss with your clinician if this is a concern

• Hair loss accompanied by other symptoms such as fatigue, pallor, or breathlessness, which could indicate iron deficiency anaemia

• Persistent hair thinning that does not improve despite disease remission

• Scalp symptoms such as pain, inflammation, pustules, marked scaling, or any suggestion of scarring — these features warrant prompt dermatology referral, as they may indicate a primary scalp condition requiring specialist assessment

• Loss of eyebrows or eyelashes, which should also be assessed by a dermatologist

Your IBD team may arrange blood tests to check for nutritional deficiencies, inflammatory markers, and thyroid function. Thyroid disorders — which can also cause hair loss — are included in the standard work-up for hair loss assessment and a TSH (thyroid-stimulating hormone) test is a routine part of this evaluation. A referral to a dermatologist may be appropriate if the pattern of hair loss suggests a primary scalp or follicular condition, or if hair loss is rapidly progressive.

It is also worth discussing any concerns about specific medications with your IBD nurse or consultant. If you believe a medicine may be causing hair loss, this can be reported to the MHRA via the Yellow Card scheme (yellowcard.mhra.gov.uk). Decisions about adjusting treatment should always be made collaboratively, weighing the risks of undertreated disease against the impact of side effects on quality of life.

Managing Hair Loss Alongside Crohn's Disease

Achieving disease remission is the most important step in managing Crohn's-related hair loss, supported by regular nutritional monitoring, dietitian input, and targeted supplementation under medical supervision.

Managing hair loss in the context of Crohn's disease requires a holistic approach that addresses both the underlying disease and any contributing factors such as nutritional deficiencies or medication side effects. In many cases, hair loss is reversible once the root cause is identified and treated, though recovery takes time: shedding may continue for several months after a trigger is resolved, and visible regrowth typically takes three to six months or longer.

Achieving and maintaining disease remission is arguably the most important step. When Crohn's disease is well controlled, the systemic inflammation and physiological stress that drive telogen effluvium are reduced, allowing the hair growth cycle to normalise. Working closely with your IBD team to optimise your treatment plan is therefore central to managing hair health.

From a nutritional standpoint, the following strategies may be helpful:

• Regular blood monitoring to identify and treat deficiencies in iron, vitamin B12, vitamin D, zinc, and folate — guided by ECCO, BSG, and NICE recommendations for IBD monitoring

• Dietary advice from a registered dietitian with experience in IBD, who can help optimise nutrient intake within the constraints of individual food tolerances (access to dietetic support is a standard component of UK IBD care per IBD UK Standards)

• Targeted supplementation as directed by your healthcare team — self-prescribing high-dose supplements without guidance is not recommended, as some can interfere with medication, affect laboratory results (e.g., high-dose biotin), or cause harm (e.g., excess zinc causing copper deficiency)

For hair loss that persists despite good disease control and nutritional optimisation, a dermatology referral may be appropriate. Topical minoxidil is licensed in the UK for hereditary (androgenetic) hair loss. Its use for telogen effluvium or other hair loss types is off-label and should only be considered under clinician guidance on a case-by-case basis. Minoxidil is generally not recommended during pregnancy or breastfeeding; if you are pregnant, planning a pregnancy, or breastfeeding, seek medical advice before using any hair loss treatment.

Finally, the psychological impact of hair loss should not be minimised. Many IBD services in the UK offer access to clinical psychologists or counsellors who can provide support. Charities such as Crohn's & Colitis UK and Alopecia UK also offer peer support resources that some patients find valuable in coping with the wider effects of living with inflammatory bowel disease.

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