3 MHz Ultrasound in Aesthetic Applications

Ultrasound is often mentioned in aesthetic medicine – but what does it really mean when people say “3 MHz”? In this article, I explain why this particular frequency has a special physiological effect, how depth of action and heat effects interact, and what beauticians should pay attention to so that treatments with 3 MHz are safe, effective and sustainable.

What does “3 MHz ultrasound” mean?

MHz stands for megahertz, i.e. millions of oscillations per second.
An ultrasound device with 3 MHz emits sound waves that propagate through tissue and are absorbed there – the higher the frequency, the more superficially this generally happens.
The absorption of sound energy generates heat and mechanical effects (e.g. micro-vibration) and can set biological processes in motion (e.g. blood circulation, metabolism) – without destroying the tissue.

Depth and heat: how deep does 3 MHz really work?

A key aspect is the penetration depth – i.e. how deep the sound energy penetrates the tissue and how much the temperature rises.

Studies show that 3 MHz ultrasound can effectively heat superficial tissue (e.g. skin, upper dermis) at depths of approximately 0.8–1.6 cm [1].
In experiments at 3 MHz, a temperature increase to 40 °C was even observed at a tissue depth of 2.5 cm [1].
The higher the frequency, the more strongly ultrasound acts superficially – while the penetration depth decreases at the same time.

Biological effects of 3 MHz ultrasound

Why does 3 MHz have not only a physical effect (heat) but also a biological one?

Increased blood circulation – heat causes the blood vessels to dilate and increases the supply of oxygen and nutrients.
Stimulation of collagen and elastin – mild heat and mechanical vibration stimulate cells to form new structural proteins [2].
Fat cell activation (lipolysis) – ultrasound stimulates fat cells to release stored triglycerides without destroying the cells [3].
Anti-inflammatory effects and regeneration – gentle ultrasound can have a positive influence on inflammatory processes [4].

| Factor | Significance

| What to pay particular attention to | | --- | --- | --- | | Intensity and duration | The heat must be sufficient but must not cause damage. | Set parameters carefully, monitor skin reactions. | |

Coupling medium (gel / oil)

Good conductivity is crucial.

Avoid air bubbles, use special ultrasound gel.

| |

Tissue depth

| Different zones require an adapted frequency. | 3 MHz is ideal for skin and subcutaneous fat. | |

Repetitions / course of treatment

| Lasting results come from a series of treatments. | Plan courses of treatment, document results. | |

Safety

Avoid overheating.

| Follow the manufacturer's instructions and check the skin. |

Legal framework: the NiSV in beauty salons

Since the end of 2020, the NiSV (Ordinance on Protection against the Harmful Effects of Non-Ionising Radiation) has applied in Germany. It regulates the use of non-ionising radiation in cosmetics, including ultrasound, radiofrequency, lasers and electrical stimulation.

For beauticians, this means:

Proof of expertise: Ultrasound treatments may only be carried out with recognised expertise.
Documentation requirement: Every treatment and its parameters must be recorded.
Client safety: Skin history, information and consent are mandatory.

More information from the German Federal Office for Radiation Protection:

NiSV at the BfS

Distinction from other ultrasound technologies

1 MHz vs. 3 MHz: 1 MHz works deeper but more slowly; 3 MHz works superficially to medium-deep and faster [1].
HIFU: focused ultrasound that deliberately destroys tissue – in contrast to gentle 3 MHz applications, which have a regulating effect [5]. Please note: high-intensity focused ultrasound (HIFU) may only be used by physicians.

Conclusion

Ultrasound at 3 MHz is a gentle but effective method – scientifically founded and clearly regulated by law. For beauticians, it is a technique that delivers results without damaging tissue and that can be used in compliance with the NiSV.

Sources

[1] Hayes BT et al. Comparisons of heating using 1- and 3-MHz ultrasound. PMC522144

[2] Lee et al. Facial rejuvenation using ultrasound. SCIRP Journal

[3] Warner-Palacio et al. Noninvasive fat reduction using ultrasound therapy. MDPI

[4] Zhou et al. Therapeutic ultrasound and inflammation modulation. PMC7922048

[5] American Institute of Ultrasound in Medicine. Safety of cosmetic ultrasound. AIUM Statement

Note: This article is for general information only and does not replace medical advice, diagnosis or treatment.