You know the face. Puffy around the eyes, a little red across the cheeks, a jawline that has gone soft overnight. Skin that looks tired however much you slept and reacts to things it used to love.

That is inflammation, and it has become the most talked-about word in beauty.

A little of it is healthy. It is how skin protects and repairs itself. The trouble is the low, constant kind that never quite switches off. Scientists call it inflammaging, and dermatologists now see it as the thread running through how skin ages. “Inflammation doesn’t replace these key ageing factors,” the consultant dermatologist Dr Aiza Jamil told Marie Claire, “but rather amplifies and links them.”

So the conversation has moved. Where beauty once chased glow, it now talks about calming things down. Three subjects keep coming up.

Red light

This is the one everyone is asking about.

The idea is that red light works on the tiny engines inside our cells, helping them do their job better. In the skin, the effects researchers are interested in are the ones beauty cares about most: collagen, blood flow and inflammation at the level of the cell.

It used to live in the clinic. Then came the LED mask, and red light moved into the bedroom. The routine people describe is ten to fifteen minutes, a few times a week, on clean skin. It has become a ritual as much as anything, the glowing mask now as familiar on social media as the sheet mask once was.

Lymphatic drainage

If red light is the technology of the moment, this is the touch.

The lymphatic system is the body’s drainage network. It collects the extra fluid that gathers in our tissues and carries it away. Lymphatic drainage is a massage built around that idea: light, slow strokes, done with the fingers or a gua sha stone, a tool with its roots in traditional Chinese medicine.

The head facialist Izabela Pawlitka told The Irish News it works “by stimulating microcirculation, increasing blood flow and oxygen to the skin for a healthy glow”.

Part of its appeal is that it asks for nothing but time and a pair of hands.

The ingredients in the conversation

Listen to dermatologists talk about inflamed skin and the same names come round again: niacinamide, azelaic acid, ceramides, vitamin C, retinoids, and antioxidants such as ferulic acid and resveratrol. None of them is new. What has changed is the reason they are being talked about.

And underneath all of it sits the sun. “UV radiation remains the number one driver,” the consultant dermatologist Dr Anjali Mahto told Marie Claire.

The case for less

There is a twist. Dr Mahto also names the misuse of skincare as one of the things that inflames skin in the first place. The ten-step routine, it turns out, may be part of the story.

Which is perhaps why inflammation has caught on in the way it has. It gives a name to the face in the mirror, and it has changed what we ask of beauty. Not brighter, tighter, more. Just skin that has settled.

Four to know

The names that come up again and again.

Red light

• CurrentBody Skin LED Light Therapy Face Mask: Series 2. Red and near-infrared light.
• Shark CryoGlow. Red, blue and infrared light, with under-eye cooling.

Lymphatic drainage

• FaceGym Multi-Sculpt. A contouring tool from the facial workout studio.
• OSEA Gua Sha Sculptor. A gua sha from the Malibu skincare brand.