Microneedling Infection: Is the Scalp at Risk?

Microneedling for Hair Loss

In the last decade, microneedling has garnered attention in the anti-aging world for its ability to remodel collagen and reduce the appearance of scars. More recently, researchers have started testing microneedling as a treatment for hair loss disorders – including androgenic alopecia.

Microneedling for hair loss

The process of microneedling creates potentially hundreds of micro wounds on the scalp. This leads to the question: does microneedling for hair loss carry a risk of infection?

How Does Microneedling Work?

In order to assess the risks involved with microneedling, one must understand the process of the procedure. Microneedling – also known as percutaneous wound induction – is the act of deliberately wounding skin tissues for therapeutic benefit. This is generally done with hundreds of tiny, medical-grade needles ranging in lengths from 0.1mm to 5.0mm.

Microneedling evokes low levels of inflammation in the scalp tissue. This inflammation evokes a reaction from the body: growth factors and signaling proteins recruited in wound repair.

Over many wounding sessions (and months), these growth factors and proteins should help to induce new collagen (i.e., skin proteins), create new blood vessels (i.e., angiogenesis), and maybe restore the functionality of damaged skin. As such, repeated microneedling sessions might improve the appearance of scars, wrinkles, and pigmentation disorders.

Does Microneedling Carry a Risk of Infection?

Needle length is especially important when evaluating the risk of infection from microneedling.

The emissary veins in the scalp tissue are the greatest concern when it comes to possible infection. This is because these veins flow bidirectionally through the skull bones and into and out of the brain. These veins reside at least 3mm beneath the surface of the scalp tissue. If needles puncture these veins, there would be some risk of infection.

Staph infections from microneedling have been reported. These cases are likely due to overuse and/or improper sterilization. Dermarollers, pens, and stamps should always be sterilized after every use.

As previously stated, the range of acceptable needle lengths used when microneedling does include depths of up to 5mm. Using the longest of these needles would indeed increase the risk of incurring an infection. However, in a literature review[1]https://link.springer.com/article/10.1007/s13555-021-00653-2 published by our team, the studied needle lengths for hair loss related to microneedling are between 0.5mm-2.5mm. In fact, it appears that the optimal needle length for hair-related microneedling is well under 3mm.

Microneedling for Hair Loss: Best Needle Length

Microneedling for hair loss has promising, if limited, data suggesting it is a good treatment option for certain hair loss sufferers. The most important factor in considering whether or not there is a risk of infection seems to be the needle length.

The best practices outlined in the literature review include using needle lengths between 0.6mm-0.8mm for automated devices and 1.25mm-1.5mm for manual rollers. When using these needle lengths, the wounds created should fall well short of the emissary veins. Therefore, very little chance of creating a pathway into the bloodstream exists.


1 https://link.springer.com/article/10.1007/s13555-021-00653-2

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