Can Weight-Loss Injections Cause Hair Loss?

Hair loss may occur in some people using weight-loss injections. In clinical trials of certain weight-management medicines containing semaglutide and tirzepatide, hair loss was reported more frequently than with placebo. However, hair loss cannot always be attributed to the medicine directly damaging the hair follicles. Rapid weight loss, significant appetite reduction, insufficient protein and energy intake, iron deficiency, thyroid disease and intense physical stress may also trigger hair loss.

Current product information states that hair-loss events reported during semaglutide and tirzepatide treatment were associated with weight reduction. This suggests that, at least in some people, hair loss may be related more to the body’s response to rapid changes in weight and nutrition than to a direct toxic effect on the hair follicle. However, the actual cause cannot be confirmed without an examination and assessment of the person’s health history.

When hair loss is noticed during weight-loss injection treatment, the person should not stop the medicine or change the dose independently. The type and timing of hair loss, rate of weight reduction, dietary pattern, other medicines and accompanying symptoms should first be assessed.

How Common Is Hair Loss With Weight-Loss Injections?

The frequency of hair loss may differ according to the active ingredient, dose, clinical trial population and amount of weight lost. Hair loss does not occur in every user, and rates reported in clinical trials do not mean that a particular person will definitely experience it.

Current Wegovy prescribing information from the U.S. Food and Drug Administration reports hair loss in approximately 3.3% of adults treated with weekly 2.4 mg semaglutide for weight management, compared with 1% in the placebo group. The product information states that hair-loss events were associated with weight reduction. In a trial involving adolescents aged 12 years and over, hair loss was reported in 4% of the semaglutide group and 0% of the placebo group.

Current prescribing information for tirzepatide-containing Zepbound reports hair loss in approximately 4% to 5% of the different dose groups, compared with 1% in the placebo group. The detailed assessment states that hair loss was associated with weight reduction and was reported more frequently in female than male participants.

These percentages should not be used to compare medicines directly. The participants, monitoring periods and assessment methods of clinical trials may differ.

Is Hair Loss A Direct Side Effect Of The Medicine?

Although hair loss is included as an adverse effect in the product information for certain weight-management medicines, the mechanism may not be the same for every person. Current semaglutide and tirzepatide product information associates hair-loss events with weight reduction. Rapid weight loss and dietary changes may therefore play an important role.

When appetite decreases significantly, a person may skip meals, eat very small portions or consume insufficient protein, iron and other nutrients. The physiological change caused by weight loss may also affect the hair-growth cycle. This pattern may often be consistent with a common and usually temporary form of hair shedding called telogen effluvium.

However, hair loss should not automatically be attributed only to the weight-loss injection. Hereditary hair loss, thyroid disease, iron deficiency, a recent infection, surgery, childbirth, severe stress, hormonal changes and other medicines may also cause hair loss during the same period.

What Is Telogen Effluvium?

Telogen effluvium is a common form of hair loss that develops when a large number of hairs enter the resting and shedding stages of the normal hair-growth cycle at the same time. It usually appears as generalised, non-scarring shedding across the scalp rather than isolated bald areas.

Normally, only a proportion of hairs are in the resting and shedding stage. In telogen effluvium, the percentage of hairs entering this stage increases. A person may notice more hair than usual in the shower, hairbrush, on the pillow or on clothing. Significant redness, wounds or permanent scarring of the scalp are not expected features.

Possible triggers of telogen effluvium include:

• Rapid or significant weight loss

• Very-low-calorie or extremely restrictive diets

• Insufficient protein and energy intake

• Severe infection or an illness involving high fever

• Surgery or physical trauma

• Childbirth and hormonal changes

• Significant psychological stress

• Starting or stopping certain medicines

• Iron deficiency

• Thyroid disease

Marked weight loss and extreme dieting are recognised triggers of telogen effluvium by the British Association of Dermatologists.

When Does Hair Loss Begin?

Telogen effluvium usually does not begin immediately after the triggering event. Because of the hair-growth cycle, noticeable shedding may occur approximately two to four months after rapid weight loss, severe illness, dietary changes or another physical stress.

A person may focus on the most recent injection dose when they notice hair loss, even though the actual trigger may have been rapid weight loss several months earlier, reduced food intake after dose escalation or a recent illness.

The following dates may be recorded when assessing the timing:

• Date the weight-loss injection was started

• Date of the most recent dose increase

• Period during which weight loss accelerated

• Period during which appetite decreased significantly

• Episodes of vomiting or diarrhoea

• Date of a febrile illness or surgery

• Childbirth or changes in hormonal treatment

• Dates when other medicines were started

This timeline may help identify a possible trigger during a dermatology assessment.

How Can Rapid Weight Loss Trigger Hair Loss?

The body may interpret rapid weight loss as a significant physiological change. When energy and nutrient intake fall substantially, the body may temporarily slow less urgent processes such as hair growth while prioritising essential functions. More hairs may then enter the resting stage and begin to shed several months later.

Weight-loss injections may help people eat smaller portions by reducing appetite. However, eating very little, skipping meals for long periods or consuming only a limited variety of foods may make it difficult to obtain sufficient nutrition. While using weight-management medicines, the nutritional quality of food is as important as the amount consumed.

Very rapid weight loss does not by itself mean that treatment is more successful. When there is significant fatigue, muscle loss, menstrual irregularity, marked hair loss or persistent dizziness, the rate of weight loss, medicine dose and nutrition plan should be reassessed by a physician and dietitian.

Can Insufficient Protein Increase Hair Loss?

Protein is an important component of the hair shaft. Inadequate intake of protein sources because of reduced appetite may contribute to hair shedding and muscle loss during rapid weight reduction.

Maintaining adequate nutrition and protein intake is important while using weight-management medicines. Protein is needed not only for hair health but also to preserve muscle mass and everyday strength during weight loss.

Depending on the person’s health, protein intake may be supported with foods such as:

• Eggs

• Yoghurt and kefir

• Cheese

• Fish

• Chicken and turkey

• Lean meat

• Lentils, chickpeas and beans

• Tofu and other soy products

• Nuts and seeds

Daily protein requirements vary according to age, body weight, physical activity and kidney function. People with chronic kidney disease should obtain medical or dietitian advice before beginning a high-protein eating plan.

Can Iron Deficiency Cause Hair Loss?

Iron deficiency is one possible cause considered during the assessment of generalised hair loss. Heavy menstrual bleeding, highly restrictive diets, low intake of meat or animal products, recent surgery and gastrointestinal conditions may increase the risk of iron deficiency.

Hair loss associated with iron deficiency may be accompanied by:

• Fatigue

• Reduced exercise tolerance

• Paleness

• Dizziness

• Palpitations

• Shortness of breath

• Brittle nails

• Restless legs symptoms

Iron supplements should not be started without assessment in everyone experiencing hair loss. Excess iron may also cause health problems, so a full blood count, ferritin and other iron studies should be evaluated by a physician. Full blood count and ferritin are among the tests that may be considered when assessing diffuse hair loss.

Can Thyroid Disease Affect Hair Loss?

An underactive or overactive thyroid may affect the structure and growth cycle of hair. Thyroid disease may cause thinning, diffuse shedding, dryness, breakage and loss of hair from the outer edges of the eyebrows.

Other possible symptoms of thyroid disease may include:

• Unexplained fatigue

• Feeling unusually cold or sweating excessively

• Constipation or frequent bowel movements

• Palpitations

• Menstrual irregularities

• Weight changes that differ from expectations

• Swelling in the neck

• Dry skin

• Trembling hands

The onset of hair loss during weight-loss injection treatment does not automatically indicate thyroid disease. However, TSH and other thyroid tests may be considered when the symptoms and medical history suggest a need. Thyroid-function testing is included in clinical pathways for the assessment of diffuse hair loss.

Which Vitamin And Mineral Deficiencies May Be Investigated?

The same vitamin and mineral panel is not required for everyone experiencing hair loss. Test selection should be planned according to dietary habits, symptoms, existing conditions and physical examination findings.

When clinically indicated, a physician may request:

• Full blood count

• Ferritin and iron studies

• TSH and thyroid-function tests

• Vitamin B12

• Folate

• Vitamin D

• Zinc

• Kidney and liver function tests

• Blood glucose and HbA1c

• Hormonal assessments

Full blood count, ferritin and thyroid-function tests are among the more commonly considered investigations for diffuse hair loss. Other tests should be added only when clinically appropriate.

Why Does The Pattern Of Hair Loss Matter?

The appearance of hair loss may help distinguish the underlying cause. Telogen effluvium usually causes diffuse shedding across the entire scalp. A significantly receding hairline or a completely bald isolated area is not typical.

Different patterns may suggest different causes:

• Diffuse shedding across the scalp: Telogen effluvium, iron deficiency, thyroid disease or medicine effects may be considered.

• Smooth, round bald areas: An immune-related condition such as alopecia areata may be possible.

• Gradually increasing thinning over the crown: Female- or male-pattern hereditary hair loss may be present.

• A receding hairline: Hereditary hair loss, tight hairstyles or certain forms of scarring alopecia may be investigated.

• Redness, scaling and itching: Eczema, psoriasis, fungal infection or another scalp condition may be present.

• Shiny, scarred areas where follicular openings are no longer visible: Prompt dermatology assessment may be required for scarring hair loss.

Effective treatment depends on identifying the type of hair loss. Dermatologists may use scalp examination, a hair-pull test, dermoscopy and, when necessary, blood tests or biopsy.

Is Hair Loss Permanent?

Telogen effluvium associated with rapid weight loss or dietary changes is usually a non-scarring and temporary form of hair shedding. When the trigger resolves, the normal hair-growth cycle may gradually return.

Shedding may continue for several months, and visible regrowth takes time. Because hair grows slowly, returning to the previous density may not be immediately noticeable even after shedding decreases. Telogen effluvium may resolve within six to nine months in many people, but the process may take longer when the trigger continues or another hair condition is present.

Whether hair loss is permanent cannot be determined only by how long it has continued. Hereditary hair loss, alopecia areata and scarring hair disorders may require different treatment and monitoring.

Should The Weight-Loss Injection Be Stopped Because Of Hair Loss?

A person should not stop a weight-loss injection independently after noticing hair loss. Sudden or unplanned discontinuation may affect appetite, weight management and diabetes control. When a treatment or medicine is suspected of causing hair loss, the prescribing physician should be consulted first.

The physician may consider:

• Reviewing the rate of weight loss

• Assessing daily food and protein intake

• Requesting blood tests

• Reviewing other medicines

• Delaying the next dose escalation

• Assessing tolerance of the current dose

• Recommending dermatology or dietitian consultation

• Considering a treatment interruption or alternative medicine

The decision to continue, change the dose or stop treatment should be made by a physician after considering the severity of hair loss, benefits of treatment, other adverse effects and overall health.

How Should You Eat To Help Reduce Hair Loss?

During weight-loss injection treatment, nutrition should focus not only on reducing calories but also on food quality. Even when portions become smaller because of reduced appetite, balanced intake of protein, vegetables, whole grains, healthy fats and other food groups remains important.

The following points may be considered:

• Avoid skipping meals for long periods.

• Include a protein source in every main meal.

• Alternate between eggs, fish, yoghurt, meat and pulses.

• Maintain a variety of vegetables and fruit.

• Do not follow very-low-calorie diets without supervision.

• Do not rely only on crackers or bread because of nausea.

• Consume sufficient fluids.

• Do not treat rapid weight loss as the only measure of success.

When appetite is very low, smaller but nutrient-dense meals may be planned. A dietitian and the prescribing physician should be consulted when sufficient food cannot be consumed, vomiting recurs or weight loss is very rapid.

Should Biotin And Hair Vitamins Be Used?

It is not appropriate to begin biotin, iron, zinc or multi-ingredient hair supplements without assessment when hair loss starts. Supplements should be planned when a deficiency is identified or when considered necessary by a physician.

High-dose biotin may interfere with certain laboratory test results. Supplements may also fail to address the actual cause of telogen effluvium. When hair loss is associated with rapid weight reduction, inadequate protein intake, thyroid disease or another scalp disorder, the underlying cause needs to be identified.

The terms “hair vitamin”, “collagen”, “fat burner” or “herbal” do not guarantee that a product is safe or effective. All supplements should be reported to the dermatologist and the physician managing the weight-loss treatment.

What Should Be Considered In Hair Care?

Hair-care changes do not treat the underlying cause of telogen effluvium, but they may reduce breakage and mechanical damage.

The following methods may help protect the hair:

• Avoid pulling the hair into very tight styles.

• Limit tight braids, extensions and heavy hairpieces.

• Do not brush wet hair aggressively.

• Reduce the use of high-heat straighteners and curling tools.

• Avoid frequent bleaching and chemical treatments.

• Wash the hair gently and avoid rubbing it harshly with a towel.

• Stop products that irritate the scalp.

Washing the hair does not cause telogen effluvium. Hairs seen during washing are generally hairs that have already entered the shedding stage. Avoiding hair washing or brushing completely does not stop the process.

How Can New Hair Growth Be Recognised?

As telogen effluvium begins to improve, the amount of hair shed each day may decrease first. Short, fine new hairs may later become visible around the hairline and parting.

Visible regrowth may take time. Because hair grows slowly, there may be several months between the reduction in shedding and restoration of hair density. Counting hairs or taking photographs every day may increase anxiety.

Monthly photographs taken with the same lighting, angle and parting may provide a more useful way to monitor change. However, photograph monitoring alone is not sufficient when there is clear worsening.

When Should A Dermatologist Be Consulted?

A dermatology assessment should be obtained when hair loss is significant, persistent or appears different from telogen effluvium. An accurate diagnosis is the basis of effective treatment.

A dermatologist should be considered when:

• Hair shedding continues to increase for several months

• Noticeable areas of scalp become visible

• Hair loss is round or localised

• Eyebrows or eyelashes are also affected

• There is scalp pain, burning or tenderness

• Redness, scaling, sores or severe itching occur

• Shiny or scarred areas appear on the scalp

• There is a family history of severe early hair loss

• Hair loss is accompanied by fatigue, menstrual irregularity or palpitations

• There is rapid weight loss and inadequate nutrition

• Hair loss significantly affects psychological well-being

Dermatology assessment should not be delayed for scarring, inflamed, extensive or unexplained hair loss.

Which Symptoms Require Urgent Medical Assessment?

Hair loss alone is not usually an emergency. However, when it is accompanied by serious general symptoms during weight-loss injection treatment, a routine dermatology appointment should not be awaited.

Prompt medical assessment is required when there is:

• Recurrent or persistent vomiting

• Inability to consume fluids

• A significant reduction in urine output

• Severe and persistent abdominal pain

• Abdominal pain radiating to the back

• Fainting

• Altered consciousness

• Swelling of the face, tongue or throat

• Significant shortness of breath

• Yellowing of the skin or eyes

• Rapidly worsening general health

In cases of severe shortness of breath, altered consciousness, seizure, fainting or rapidly worsening general health, an online consultation should not be awaited. Emergency services should be contacted or the nearest emergency department should be visited.

This content is provided for general informational purposes. The cause of hair loss and decisions concerning continuation, dose changes and treatment options for weight-loss injections require an individual medical assessment.

Plan Your Online Dermatology Doctor Consultation With Happ Health

With the “Health Everywhere, For Everyone, Always.” approach, we believe that hair loss developing during weight-loss injection treatment should not be considered only as a medicine side effect. It should be assessed together with the rate of weight loss, nutritional status, iron and thyroid values, other medicines and scalp findings.

By planning an Online Dermatology Doctor consultation through Happ Health, you can have the onset and pattern of hair loss, weight changes, medicines and recent laboratory results assessed. A dermatologist may evaluate whether the hair loss is associated with telogen effluvium, hereditary hair loss, alopecia areata or another scalp condition and provide guidance regarding the necessary tests.

Preparing the date when hair loss began, the name of the weight-loss injection and dose changes, weight lost during recent months, a list of medicines and supplements, recent laboratory results and clear photographs of the scalp from different angles may make the online assessment easier. When a hair-pull test, dermoscopic examination, physical examination, biopsy or additional laboratory testing is required, you may be referred to an in-person healthcare institution.

When hair loss is accompanied by recurrent vomiting, inability to consume fluids, significant weakness, fainting, severe abdominal pain, shortness of breath or rapidly worsening general health, an online dermatology consultation should not be awaited and a healthcare institution should be contacted.

References

• Turkish Medicines And Medical Devices Agency, Wegovy Summary Of Product Characteristics:
  https://www.titck.gov.tr/storage/Archive/2025/kubKtAttachments/WEGOVY0.5KB_17_02_2025.pdf

• Turkish Medicines And Medical Devices Agency, Mounjaro Summary Of Product Characteristics:
  https://www.titck.gov.tr/storage/Archive/2026/kubKtAttachments/25YAYINLANACAKkb_12_03_2026.pdf

• U.S. Food And Drug Administration, Current Wegovy Prescribing Information:
  https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215256s025lbl.pdf

• U.S. Food And Drug Administration, Current Zepbound Prescribing Information:
  https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/217806s042lbl.pdf

• British Association Of Dermatologists, Telogen Effluvium:
  https://www.bad.org.uk/pils/telogen-effluvium

• National Health Service, Hair Loss:
  https://www.nhs.uk/symptoms/hair-loss/

• NHS Scotland, Alopecia Clinical Pathway:
  https://www.rightdecisions.scot.nhs.uk/dermatology-pathways/alopecia/

• Guy’s And St Thomas’ NHS Foundation Trust, Dietary Advice For People Taking Weight-Loss Medicines:
  https://www.guysandstthomas.nhs.uk/health-information/dietary-advice-people-taking-weight-loss-medicines

• American Academy Of Dermatology, Hair-Loss Diagnosis And Treatment:
  https://www.aad.org/public/diseases/hair-loss/treatment/diagnosis-treat