Risk Identifiers for Fibroblast Patch Testing

• History of keloid (raised) scarring from skin trauma
• Ethnic background – asian genetics can be predisposed to keloid scarring
• Fitzpatrick scale – the higher the ranking, the higher the risk of hyperpigmentation following any trauma to the skin
• Previous allergies to topical anaesthetics

Once you have identified that a client requires patch testing, then what do you do? The best procedure for patch testing varies according to the service you are testing for. I will outline each below.

Patch testing for Cosmetic Tattooing & Microblading Clients

What to patch test for:  topical anaesthetic allergies, pigment allergies

When to patch test:  48 hours before the treatment itself

Where to patch test: While cosmetic tattoo pigments are semi permanent there is always a risk that a portion of the pigment will never fully disappear from the clients skin. For this reason I recommend that patch testing be carried out in an inconspicuous area. My favourite is just beyond the hairline, behind the client ear. This is a spot where any lingering pigment will not be visible or unsightly. You only need to test with a small amount of pigment. You can use a micro blade or lance to scratch the skins surface and implant a small amount of the pigment.

To patch test for topical anaesthetic reactions you can place a small amount of numbing cream anywhere on the skin and monitor the area for 10-15 minutes.  I find it easiest to draw a circle on the skin around the area to be tested. You can also apply an occlusive or barrier film over the applied topical anaesthetic to speed up the application time and prevent the cream from being accidentally rubbed off.

What to look for: if the client has an allergy to the anaesthetic they will report a burning or stinging sensation while the cream is in contact with the skin. The skin will also flush red where the cream has been applied.

If the client has a reaction to the pigment the area will appear red and inflamed with significant swelling, and weeping from the wound itself. The body will be trying to ‘push’ the pigment/irritant out of the skin.

Patch testing for Henna Brow Clients

What to patch test for:  pigment allergies

When to patch test:  48 hours before the treatment itself

Where to patch test:  Similarly to cosmetic tattooing it is best to patch test in a small inconspicuous area such as just beyond the hairline behind the clients ear. Apply a small amount of the henna product you use and leave for 10-15 minutes before removing as normal.

What to look for: If the client has a reaction to the pigment the area will appear red and inflamed with significant swelling. It may appear to have a blister on the skin.

Patch testing for Plasma Fibroblast Clients

What to patch test for:  topical anaesthetic allergies ,  hyperpigmentation

When to patch test:  3-6 weeks  before the treatment itself

Where to patch test: To patch test for topical anaesthetic reactions you can place a small amount of numbing cream anywhere on the skin and monitor the area for 10-15 minutes. I find it easiest to draw a circle on the skin around the area to be tested. You can also apply an occlusive or barrier film over the applied topical anaesthetic to speed up the application time and prevent the cream from being accidentally rubbed off.

To patch test for hyperpigmentation it is recommended to perform a small plasma treatment patch of about 1 square cm of skin in an inconspicuous area. Remember that the skin on the body can take twice as long to show the final healed result as the skin on the face. So if you are intending to perform a treatment on the clients tummy, you will want to patch test on the body and allow additional healing time before analysing the result. If you are intending to perform a treatment on the clients face then it is best to patch test behind the ear for an accurate prediction of the healing result.

What to look for: if the client has an allergy to the anaesthetic they will report a burning or stinging sensation while the cream is in contact with the skin. The skin will also flush red where the cream has been applied. If the client shows any sign of developing unwanted dark pigmentation on the treated area then it is not recommended to perform the plasma treatment.

Patch testing your clients is one of those tasks that seems completely unnecessary 99% of the time, but the 1% of your clients that will react make the other 99% completely justified. As a cosmetic tattoo and plasma fibroblast artist myself I have never encountered allergies to the pigments I use, and have only once encountered a client who had an adverse reaction to the topical anaesthetic used. Although rare, it does happen and it’s much better to find out ahead of time, rather than halfway into a treatment.

Hopefully the guides above can help you identify clients who may require patch testing prior to treatment. Whether you choose to patch test or now, you should always offer your clients the option to request a patch test themselves at the time of consultation.

Did you find this article helpful? Please leave some feedback in the comments below, or request a particular topic for my future posts.

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