Why Do I Have Thinning Hair on One Side of My Head Only?'

Name: Chris

Question: Hi. The entire right side of my head has 1/2 the amount of hair my left side does, even my neck…. this has been going slowly for years and is bothering me. Have you heard of this and also, is this a genetic issue? I do not know where to go - if you literally would split my head in halves, the right side is thinner.

Answer: Hi, Chris. This is certainly an unusual phenomenon but there are a few reasons that your hair may be thinner on one side than the other.

Although Male Pattern Baldness can cause thinning hair in the areas where genetically-predisposed follicles are located, along the top of the scalp from the crown to the hairline and temporal regions, and is not always typically symmetrical, we would rule this out. The pattern of thinning that you describe is unlikely to be Androgenetic Alopecia due to you mentioning areas outside those susceptible to this hereditary hair loss condition.

This difference may simply be due to hair follicle distribution; if it is sparser on one side of your head, the less hairs there are, the thinner your hair will feel. This could also be a 'cup half full/empty' conundrum where one side may actually be unusually thick due to more follicles, rather than the other side being thin due to having less.

Sometimes you will notice people have more than one hair per follicle. This can happen due to two or more follicles merging where the hair appears and their respective hairs all emerging from the same scalp follicle. This is called a compound follicle. A number of instances of pili multigemini, where two or three hair shafts grow from the same follicle, could also be present.

Both of these, if present in significant numbers, could certainly create extra hair density if this happens more in one part of the scalp than the other and does not mean one side is thinning, it may simply have a normal amount of volume, but appears thin when compared to the extra-dense areas.

Another potential cause of thinner hair or hair loss on one side of the scalp is an underlying circulatory issue. A good blood supply full of the nutrients needed for healthy hair growth is essential. If this is hindered in any way, the hair can suffer as a result.

We recommend speaking to a dermatologist who can assess your scalp and, if required, can refer you for blood tests, should a circulatory or dietary issue be suspected. Assuming you are not worried about losing your hair, and are concerned to find out why one side is different to the other, your hairdresser or barber should be able to create a flattering asymmetrical haircut that makes the most of the volume you have.