The life cycle of hair consists of three phases:
- Anagen (Growth Phase): This is the active phase where hair grows, lasting 2 to 7 years. About 85% of hair is in this phase at any given time.
- Catagen (Transition Phase): A short transitional phase where hair growth stops, lasting 2 to 3 weeks. Hair follicles shrink, and the hair detaches from the blood supply.
- Telogen (Resting Phase): The hair is at rest, and eventually, it sheds. This phase lasts about 3 months, and new hair begins to grow as the cycle repeats.
How Drugs Cause Hair Loss
Drugs can cause hair loss by disrupting the normal hair cycle, primarily targeting the anagen (growth) or telogen (resting) phases:
- Anagen Effluvium: Drugs interfere with the rapidly dividing hair matrix cells during the growth phase, leading to sudden hair loss. This is common with chemotherapy drugs.
- Telogen Effluvium: Certain medications prematurely push hair follicles into the resting phase, causing hair to fall out in larger quantities after a few months.
Types of Medications That Can Harm Hair
- Chemotherapy drugs: Particularly anthracyclines, alkylating agents, and taxanes cause rapid hair loss due to their effect on rapidly dividing cells.
- Anticoagulants: Warfarin and heparin can cause telogen effluvium by affecting hair follicles’ blood supply.
- Beta-blockers: Drugs like metoprolol, propranolol, and atenolol may result in hair thinning.
- Retinoids: Isotretinoin and acitretin, used for acne and psoriasis, can lead to hair loss as a side effect.
- Antidepressants: Tricyclic antidepressants (amitriptyline) and SSRIs (sertraline, fluoxetine) may cause telogen effluvium.
- Anti-seizure drugs: Phenytoin and valproate are known to cause hair loss.
- Blood pressure medications: ACE inhibitors like enalapril and lisinopril can contribute to hair shedding.
- Hormonal therapies: Birth control pills and hormone replacement therapy (HRT) may affect hair growth due to hormonal imbalances.
- Nonsteroidal anti-inflammatory drugs (NSAIDs): Ibuprofen and naproxen can contribute to temporary hair loss.
- Cholesterol-lowering drugs: Statins (atorvastatin, simvastatin) may interfere with hair growth.
Diagnosing Hair Loss from Medications
- Medical History: Your doctor will review medications you’re taking and the timeline of hair loss.
- Hair Pull Test: Gently pulling a small number of hairs can help identify how easily they fall out.
- Scalp Examination: A dermatologist may examine your scalp to determine the type of hair loss.
- Blood Tests: Tests may be conducted to rule out other causes of hair loss, like nutritional deficiencies or thyroid issues.
Treatments for Hair Loss
- Topical Treatments:
- Minoxidil: Often used to treat hair loss by stimulating hair growth and prolonging the anagen phase.
- Steroid Creams: Applied to the scalp to reduce inflammation that may be causing hair loss.
- Medications:
- Finasteride: Oral medication that blocks the hormone DHT, responsible for male and female pattern baldness.
- Spironolactone: Used off-label to treat hair loss in women due to its anti-androgen effects.
- Hair Transplantation: For more permanent solutions, hair transplants involve moving hair from a dense area to a balding area.
- Treatments for Chemotherapy-induced Hair Loss:
- Scalp Cooling Caps: These caps cool the scalp during chemotherapy to reduce blood flow, potentially preventing the drugs from damaging hair follicles.
- Wigs or Hairpieces: Temporary solutions for chemotherapy patients.
- Topical Minoxidil: May be prescribed to stimulate hair regrowth post-chemotherapy.
- Dietary Supplements:
- Biotin: Some studies suggest it can help improve hair strength.
- Iron and Zinc Supplements: If deficiencies are detected, supplementation can support hair regrowth.
-Nguyễn Duy Khiêm-
References for Further Research
- American Academy of Dermatology (AAD): Provides detailed information on hair loss causes and treatments.
- National Cancer Institute (NCI): Offers guidelines on managing chemotherapy-induced hair loss.
- Mayo Clinic: Discusses the diagnosis and management of various hair loss conditions.
- PubMed (National Library of Medicine): Research articles on the effects of medications on hair loss.
These sources provide comprehensive information and ongoing research on how to manage and treat hair loss.