Hair loss can be a significant personal concern. While genetics, aging, and hormonal fluctuations are common contributors, infections affecting the scalp or body can also disrupt hair growth, leading to various forms of hair loss. This article explores how different infections can impact hair and when to seek professional medical guidance.
How Infections Affect Hair Growth
Infections can trigger hair loss through several biological mechanisms. Hair follicles are susceptible to damage from invading microorganisms or the body’s immune response. When an infection causes inflammation around the hair follicles, it can disrupt their normal function and the hair growth cycle. This inflammation can lead to direct damage to the hair shaft or the follicle itself, interfering with its ability to produce healthy hair.
The hair growth cycle consists of three main phases: anagen (growth), catagen (transition), and telogen (resting/shedding). Infections, particularly those causing significant systemic stress or fever, can prematurely push many hair follicles from the active growth (anagen) phase into the resting (telogen) phase. This accelerated shedding is known as telogen effluvium. Some infections can also directly attack and destroy hair follicles, leading to permanent hair loss if the damage is severe enough to cause scarring.
Common Infections Linked to Hair Loss
Many infections can cause hair loss, each with distinct effects on the scalp and hair follicles.
Fungal Infections
Fungal infections, such as tinea capitis, commonly known as ringworm of the scalp, are a frequent cause. This infection leads to itchy, scaly patches on the scalp, often with accompanying hair loss as hairs break off at or near the surface. In some severe cases, tinea capitis can cause a painful, pus-filled lesion called a kerion, which may result in scarring and permanent hair loss if left untreated.
Bacterial Infections
Bacterial infections can also impact hair health. Folliculitis, an inflammation of the hair follicles, is often caused by bacteria like Staphylococcus aureus. It manifests as small, red, pimple-like bumps around hair follicles and can lead to hair loss if severe or chronic, potentially causing permanent damage and scarring of the follicles. A more severe and rare form, dissecting cellulitis of the scalp, involves deep, painful nodules and cysts that can lead to significant scarring and permanent bald patches. Syphilis, a bacterial infection, can also cause hair loss, particularly during its secondary stage. This condition, known as syphilitic alopecia, often presents as patchy, “moth-eaten” hair loss on the scalp, eyebrows, or other body areas.
Viral Infections
Viral infections can also contribute to hair shedding. Shingles, caused by the Herpes Zoster virus, can lead to hair loss in affected areas of the scalp if the infection causes significant inflammation and scarring. Widespread viral illnesses, such as COVID-19, have been linked to an increased incidence of telogen effluvium, typically occurring a few months after the acute infection due to the body’s systemic stress response.
Parasitic Infestations
Parasitic infestations, while not directly causing hair loss, can lead to it indirectly. Head lice, for instance, cause intense itching, and persistent scratching can damage the scalp and hair follicles, leading to hair breakage or secondary bacterial infections that weaken the hair. This physical trauma and subsequent inflammation can contribute to noticeable, though usually temporary, hair thinning.
Hair Loss: Temporary or Permanent?
The prognosis for infection-related hair loss varies by infection type, severity, and follicle damage. In many instances, hair loss triggered by an infection is temporary. Once the underlying infection is treated, hair follicles can recover, and new hair growth typically resumes. This is often the case with telogen effluvium, where shedding resolves once the body recovers from the stressor.
However, if an infection causes severe inflammation or is left untreated, it can lead to permanent damage to the hair follicles. This irreversible damage results in scarring, known as cicatricial alopecia, where scar tissue replaces follicles and prevents hair production. Examples include severe tinea capitis and dissecting cellulitis of the scalp. Early diagnosis and appropriate treatment are important to minimize the risk of permanent hair loss.
When to Seek Medical Attention
It is advisable to consult a healthcare professional for unexpected or significant hair loss, especially if accompanied by symptoms suggesting an infection. These symptoms include scalp pain, itching, redness, scaling, pustules, or sores. A proper diagnosis is important to identify the specific cause and determine the most effective treatment.
During a medical consultation, a doctor may examine your scalp and hair. They might also take samples, such as skin scrapings or hair cultures, to identify fungal or bacterial pathogens. In some cases, blood tests may be ordered to check for systemic infections or other underlying conditions contributing to hair loss. Prompt medical evaluation can help ensure timely intervention and improve the chances of successful hair regrowth.