Hyaluronic acid fillers: effects, duration, risks and what you need to know before treatment

Fillers are among the most sought-after aesthetic treatments, yet they are viewed very differently depending on who you ask. Amidst advertising claims and personal accounts on social media, the medical perspective is often lost. This article explains what hyaluronic acid fillers do, what determines how long they last, and what risks are involved.

Key points at a glance

• Hyaluronic acid is a substance produced naturally by the body. As a filler, it is used in a cross-linked form to restore volume or alter contours.
• How long the results remain visible depends on the region, product, quantity and individual factors, and cannot be stated in general terms.
• Mild swelling and bruising following treatment are normal. These should be distinguished from rare but serious complications.
• Severe pain, a pale complexion or visual disturbances following an injection require immediate medical attention.

What a hyaluronic acid filler is

Hyaluronic acid occurs naturally in the body, including in the skin, where it binds water. For aesthetic use, it is produced in a laboratory and cross-linked so that it remains more stable within the tissue and is not broken down immediately. Depending on the degree of this cross-linking, products with varying degrees of firmness are produced, each intended for different purposes.

Unlike botulinum toxin, a filler does not act on muscles but restores volume. It is therefore used where volume is lacking or where a contour needs to be altered, such as on the cheeks, chin, lips or deep wrinkles that remain visible even when the face is relaxed.

Legally speaking, these are not medicinal products, but products governed by European medical device legislation. Fillers used exclusively for aesthetic purposes fall within the category of products without a medical intended purpose. Since 22 June 2023, they have been subject to specific common EU specifications. Among other things, these stipulate that the labelling and instructions for use must include a statement that the product may only be administered by appropriately trained healthcare professionals who are qualified or authorised under national law. It is also mandatory to include a clear statement that the products must not be used on persons under the age of 18. This is a different process from the authorisation of a medicinal product and one reason why the available data varies between products.

What the shelf life depends on

There is no universally applicable figure, and claims promising a fixed number of months should be treated with caution. The breakdown occurs naturally within the body and at varying rates.

This is influenced, amongst other things, by the area being treated, as areas with a lot of movement and good blood circulation break down more quickly than quieter areas. The properties of the product, the amount applied and your metabolism also play a role. There are no reliable, generally applicable figures for each region or product group. Manufacturers must provide information on the resorption time of their product, but this applies only to that specific product.

It is important to make a distinction that is often overlooked: the visible result and the remaining material are not the same thing. The aesthetic effect may diminish whilst residual material is still present in the tissue. In the case of repeated treatments, this is a reason not to rely solely on visual impressions, but to document the course of treatment to date and to specify this in the practice records.

What is normal after treatment

Immediately after an injection, redness, swelling, tenderness and minor bruising are common. These usually subside within a few days. In the first few days, the result may appear more pronounced than the final outcome, which is why it is advisable to wait until the swelling has subsided before making an assessment.

A slight feeling of tightness or palpable irregularities may also occur in the first few days. If lumps persist, they should be assessed by a doctor and not massaged yourself.

When you need immediate medical attention: Increasing or very severe pain, a noticeable white or livid discolouration of the skin, a net-like pattern on the skin, visual disturbances or pain in the eye are warning signs. They may indicate a blockage in a blood vessel. Swift action is crucial here: contact your GP’s surgery or an A&E department immediately. Under no circumstances should you attempt to treat this yourself.

What complications are possible?

In addition to the immediate reactions mentioned, there are rarer events that one should be aware of, without dramatising them. European medical device legislation requires manufacturers to assess precisely these risks and describe them clearly in the instructions for use. Among other things, these include migration of the material, nodule formation, infection and inflammation, vascular damage, necrosis and, in very rare cases, blindness.

Lumps may form if the material is unevenly distributed or if the tissue reacts to it. Infections are rare but possible, and usually manifest as redness, warmth and increasing pain after the first few days. Delayed immune system reactions involving swelling have been reported and may occur even some time after treatment, sometimes in connection with infections.

On the frequently discussed issue of migration: the displacement of material is recognised as a risk and is exacerbated by larger volumes, certain regions and repeated treatments. However, this does not mean that fillers inevitably migrate. What is presented as ‘migration’ on social media has various causes, ranging from actual displacement to excessive volumes and swelling. An assessment can only be made following a clinical examination.

The most serious complication is vascular occlusion, where material accidentally enters a blood vessel or compresses it from the outside. It is rare, but can lead to tissue damage and, in very rare cases, affect vision. Certain areas are considered more challenging, including the area between the eyebrows, the nose and the area under the eyes.

What constitutes good patient information and an emergency plan

As serious complications are rare, the outcome depends largely on the preparation. Careful treatment involves an initial consultation with an examination, during which the team discusses what is and is not achievable, what alternatives are available and what risks are involved.

This also means that the practice must be prepared for complications. This includes having hyaluronidase to hand – an enzyme that can break down hyaluronic acid – as well as clear information on how to contact the practice outside of consultation hours. It’s worth asking this question in advance, rather than in an emergency.

It is also advisable to document which product was administered, in what quantity and in which region. The European regulations expressly require a separate section in the product documentation for this purpose, in which the location, number and volume of the injections are recorded. Ask to be given a copy of this information. It will be valuable should you require further treatment at another surgery. When looking for a surgery, it is worth checking the services on offer and how easy it is to get there. Find aesthetic medicine practitioners near you

Frequently Asked Questions

How long does a hyaluronic acid filler really last?

This depends on the region, product, quantity and individual metabolism, which is why it is not possible to give a general figure. It should also be borne in mind that the visible effect may diminish whilst material is still present in the tissue.

Can fillers migrate?

Migration is possible and is explicitly identified as a risk in medical device legislation, but it is not an inevitable outcome. Factors that contribute to this include larger volumes, specific regions and repeated treatments. Much of what is referred to online as ‘migration’ has other causes and cannot be assessed without examination.

Can fillers be dissolved?

Hyaluronic acid can be broken down using the enzyme hyaluronidase. This is a medical treatment with its own risks, including allergic reactions, and does not act exclusively on the injected material. The extent to which this is successful and the speed at which it occurs vary. Self-treatment is not an option.

From what age are fillers permitted?

For fillers not intended for medical use, European medical device legislation stipulates that the products must not be used on persons under the age of 18. This warning must appear on the labelling and in the instructions for use.

Is the treatment painful?

Many fillers contain a local anaesthetic; an anaesthetic cream may also be used. The sensation varies greatly depending on the area, with the lips being considered particularly sensitive.

Classification

Hyaluronic acid fillers are commonly used, but they are not a risk-free procedure. The difference between an uncomplicated treatment and a serious complication lies less in the product itself than in anatomical expertise, thorough patient briefing and whether the practice is prepared to deal with complications.

The most suitable treatment for your condition, and whether it is appropriate, will be determined during a consultation with a doctor, including a physical examination. View aesthetic medicine practitioners by region

Fact-checking as at: 20 August 2026. Verified key topics: regulatory classification of hyaluronic acid fillers in accordance with Regulation (EU) 2017/745, Annex XVI, and Implementing Regulation (EU) 2022/2346, Annex IV; requirements regarding the user group, age limits and documentation, warning signs and procedures in the event of suspected vascular occlusion, statements on migration and delayed reactions, hyaluronidase and its limitations, information on shelf life. Cannot be verified: Publication status of the submitted AWMF S1 guideline 013-108 on complications associated with aesthetic filler injections; the text deliberately makes no reference to it.