Bad Smell in the Hair (Offensive Hair Odor) Causes and Remedy

Hair Odor

Like the skin, hair on the body also has a distinctive odor which varies from person to person. The body odor as it is collectively known is an interplay of many factors, mainly external, that can alter the natural smell. This includes :

  • Climate – hot, cold, humid or dry.
  • Sun exposure
  • Perspiration
  • Clothing
  • Skin or hair care products
  • Personal hygiene
  • Normal skin flora – naturally occurring bacteria and fungi on the body.
  • Perfumes and scents
  • Living conditions
  • Skin diseases

Despite the different factors contributing towards body and hair odor, personal hygiene has the largest impact. Thorough washing can remove or reduce the effect of any of these factors that play a role in odor. Similarly, poor hygiene and infrequent washing may allow for a combination of smells that can eventually become offensive.

Reason for Bad Smelling Hair

Each shaft of hair is firmly rooted in the skin. It emerges into the surface through a canal known as the follicle. Also connected to this follicle is the sebaceous (oil) gland. It secretes an oily substance known as sebum which moisturizes and waterproofs the skin and hair. Different species of bacteria and fungi naturally occur on the skin yet do not usually infect it. These microbes are jointly referred to as the normal skin flora. The hair oil can act as sort of ‘glue’ which along with the thousands of hair shafts intermingled on the head traps dust, dirt and microbes in the air. In most people, regular and thorough washing of the hair and scalp will remove the dust and microbes on an ongoing basis thereby preventing it from accumulating.

Healthy hair and skin on the scalp are not usually irritated by these airborne particles or infected by the microbes.The constantly supply of dead skin cells on the scalp serves as a food source for the bacteria and fungi in particular which can gradually replicate on the head. It is usually these microbes which are consuming the decomposing conglomerates of dead skin, oil, dust and dirt that contribute to the bad smell of the hair. It is further compounded by the use of hair care products which are a common practice these days. Although these products are often scented, it does however trap even more dust, dirt and microbes. Eventually this reaches a point where the offensive odor of the hair cannot be masked by these fragrant products.

Causes of Bad Smell in the Hair

Poor Hygiene

Poor hygiene is the most common cause of bad smelling hair. It allows for the build up of dust, dirt and microbes on the hair shafts and the scalp as explained above. Some people may also wash their hair infrequently for aesthetic reasons rather than just as a matter of poor personal hygiene. Hair weaves (extensions), chemically straightened hair and many types of hair styles are not able to withstand washing. In addition, the use of specialized hair care products to maintain the weaves, straight hair and hairstyles may further exacerbate the problem by trapping even more dirt and microbes.


Environmental factors play a significant role in bad smelling hair. It differs to a large degree among individuals based to some degree on the climate, living conditions, water quality, air pollution and sun exposure. Some microbes which are more commonly found in specific regions and certain situations may also be a contributing factor in an offensive hair odor. The effect of most of these environmental factors can be minimized with good hygiene and hair care. Wearing hats, caps and scarves over the head may also be another contributing factor to smelly hair. Lifestyle measures here as well, such as reducing the time the head is covered and exposing it to sunlight can limit the impact.

Hair Products

There is a wide range of hair care products on the market with different purposes. These products are mainly styling gels, hair sprays and hair oils. The consistency of these products make it ideal candidates to serve as a substrate for trapping dust, microbes and causes the dead skin cells to clump together. Other hair care products may include those to grow hair or make it thicker, keep the hair straight, change the hair color (dyes) or help it to appear shinier. Some of these products have strong chemical odors due to its constituent ingredients. Furthermore these products may irritate the scalp thereby leading to skin diseases which subsequently develops a secondary infection.

Skin Diseases

As with skin elsewhere on the body there are a host of scalp problems that compromise the health and integrity of the skin. This includes :

  • Dandruff
  • Dryness of the skin
  • Scalp acne
  • Scalp psoriasis
  • Seborrheic dermatitis
  • Scalp ringworm
  • Head lice

On its own these skin conditions do not usually cause an offensive odor of the scalp. An itchy scalp with repeated scratching, the compromised skin barrier and infrequent washing due to the skin disease all contribute to the development of a bacterial infection. In these cases the bacterial infection is said to be secondary while the underlying disease is the primary condition. However, in conditions such as folliculitis the bacterial infection of the hair follicle is the primary condition.

It is usually the bacterial component that is most likely to be responsible for offensive smelling hair. The infected area can quickly enlarge in size as the condition spreads. There may be infected pimples, abscesses and oozing pus which may be the source of the offensive odor rather than the underlying skin disease. Hygiene needs to still be maintained to avoid these common causes of bad smelling hair although extra care is usually necessary in the setting of a skin infection.

Bad Smelling Hair Remedies

A bad smell in the hair is a symptom and the cause should therefore be identified and treated medically where necessary. This may involve the use oral medication (tablets / capsules) or topical applications (shampoos, creams, ointments and gels).  If a medical professional can conclusively rule out any underlying problem that needs medical attention then some general remedies may be useful. This includes hygienic practices and changes in lifestyle.

  • Thoroughly wash the hair and scalp with a mild shampoo on a regular basis – at the very least twice a week.
  • Fragranced hair care products can help mask the offensive odor but may also irritate the scalp thereby worsening the condition in the long term.
  • Exposing the hair to sunlight and air on a regular basis for at least 20 minutes to an hour per day.
  • Keep the hair and scalp healthy by practicing good hygiene and moisturizing the skin and hair.
  • Grooming is important. Thorough combing several times a day reduces the chances of infestations, removes excess dirt and helps keep the hair healthy.

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