Hair loss on one side of the head can be a concerning and often puzzling issue. It may present itself gradually or suddenly, and understanding the potential causes is crucial for both diagnosis and treatment. There are various factors that can contribute to this asymmetrical hair loss, ranging from medical conditions to lifestyle and external influences.
Medical Conditions
Alopecia Areata
Alopecia areata is an autoimmune disorder. In this condition, the body’s immune system mistakenly attacks the hair follicles. When it affects only one side of the head, it can cause patchy hair loss in that area. The exact cause of the immune system malfunction is not fully understood, but it may be related to genetic factors and environmental triggers. For example, stress or a viral infection might trigger an episode of alopecia areata on one side.
The hair loss usually occurs in round or oval patches. These patches can be small or large and may be more noticeable on one side if the condition is localized there.
Trichotillomania
Trichotillomania is a psychological disorder where a person has an irresistible urge to pull out their own hair. This often results in hair loss that may be more prominent on one side if the individual has a preference for pulling hair from that particular area. It could be due to habit, stress, or other underlying emotional issues.
The hair loss from trichotillomania may have an irregular pattern, with different lengths of hair in the affected area as the person may pull some hairs completely and others only partially.
Fungal Infections
Fungal infections of the scalp, such as tinea capitis, can cause hair loss on one side. The fungus attacks the hair shaft and follicles, weakening the hair and causing it to break off or fall out. This type of infection may start on one area of the scalp and spread if not treated.
The affected area may be itchy, red, and have flaky or scaly skin. The hair in that region may look dull and brittle before falling out.
Skin Conditions
Conditions like psoriasis or seborrheic dermatitis can affect the scalp and lead to hair loss on one side if the condition is more severe or localized in that area. In psoriasis, the rapid turnover of skin cells can cause thick, scaly patches that can disrupt hair growth.
Seborrheic dermatitis can cause inflammation and flaking of the scalp, which may interfere with the normal hair growth cycle. If these conditions are not properly managed, they can contribute to hair loss on one side.
Traumatic Causes
Tight Hairstyles
Wearing tight hairstyles such as braids, ponytails, or buns consistently on one side can cause traction alopecia. The constant pulling on the hair follicles can damage them over time, leading to hair loss. This is often seen in women who frequently style their hair in a particular way that puts stress on one side of the scalp.
The hair loss usually occurs along the hairline or in areas where the tension is greatest. It may start with thinning hair and progress to more significant loss if the tight hairstyle is continued.
Head Injuries
A blow to the head on one side, such as from an accident or a sports injury, can damage the hair follicles. The trauma can disrupt the blood supply to the follicles or directly affect their structure, resulting in hair loss in the affected area.
In some cases, the hair loss may be immediate, while in others, it may occur gradually as the damaged follicles enter a resting phase and stop producing hair.
Burns or Chemical Damage
Exposure to chemicals, such as harsh hair dyes or relaxers, especially if applied unevenly or inappropriately on one side, can cause hair loss. Chemical burns from these products can damage the hair and scalp, leading to breakage and loss.
Similarly, thermal burns from styling tools like curling irons or straighteners, if used incorrectly on one side, can affect the hair follicles and result in hair loss in that area.
Hormonal Imbalances
Androgenetic Alopecia
Androgenetic alopecia can sometimes present asymmetrically. While it is more commonly known as male – pattern or female – pattern baldness, it can start on one side of the head in some cases. Hormones, particularly androgens, play a role in this condition.
In men, testosterone is converted to dihydrotestosterone (DHT), which can shrink the hair follicles.
In women, hormonal changes during pregnancy, menopause, or due to conditions like polycystic ovary syndrome (PCOS) can also contribute to androgenetic alopecia. If the hormonal imbalance affects one side of the scalp more severely, it can lead to hair loss in that area.
Thyroid Disorders
Thyroid hormones regulate the body’s metabolism, including the hair growth cycle. Hypothyroidism (an underactive thyroid) or hyperthyroidism (an overactive thyroid) can cause hair loss. The hair may become thin and brittle, and if the thyroid disorder affects the blood flow or hormonal balance in one area of the scalp more than others, it can result in hair loss on one side.
Other symptoms of thyroid disorders, such as weight changes, fatigue, or changes in skin texture, may also be present.
Nutritional Deficiencies
Protein Deficiency
Protein is essential for hair growth. If there is a lack of protein in the diet, the body may prioritize its use for other vital functions, and hair growth can be affected. This can lead to hair loss that may be more noticeable on one side if the deficiency has a local impact on the hair follicles.
People following strict diets, vegetarians or vegans who may not get enough complete protein, or those with malabsorption issues are at a higher risk of protein deficiency – related hair loss.
Vitamin and Mineral Deficiencies
Deficiencies in vitamins like biotin, vitamin D, and minerals like iron and zinc can contribute to hair loss. For example, iron is necessary for the production of hemoglobin, which carries oxygen to the cells, including hair follicles. A lack of iron can lead to decreased oxygen supply to the follicles on one side or throughout the scalp.
Vitamin D is involved in the hair growth cycle, and a deficiency can disrupt normal hair growth. Biotin deficiency can cause brittle hair that may break off more easily on one side if the deficiency is unevenly distributed in the body.
Conclusion
Hair loss on one side of the head can be caused by a multitude of factors, and often, a combination of these may be at play. It is important to carefully evaluate any associated symptoms, medical history, and lifestyle factors to determine the underlying cause. If the hair loss is persistent or causes significant concern, consulting a healthcare professional or a dermatologist is advisable. Early diagnosis and appropriate treatment can help to address the issue and potentially promote hair regrowth.