Does the natural origin of hyaluronic acid guarantee its safety ?
No. Hyaluronic acid is naturally present in the body, but an injectable gel is a manufactured device with a formulation that often contains an anaesthetic. Its natural presence in the skin is therefore not enough to guarantee tolerance of the injected product.
The risks depend on the product and its components, the area treated, the technique, hygiene conditions and the patient’s medical situation. They are not limited to possible toxicity : even a compliant gel can cause a reaction or complication if it accidentally enters a blood vessel.
Being resorbable also does not mean immediate or always complete disappearance at a predictable date. The persistence of hyaluronic acid and the duration of the result must be considered before another session.
Which side effects are usual after an injection ?
Localised redness, tenderness, swelling or bruising may appear at injection sites. Their duration varies according to the area, product and individual : they may subside within a few days, but some bruising or swelling lasts longer.
These reactions are common. Increasing pain, an unusual change in skin colour or worsening swelling are not normal after-effects.
Which signs require urgent medical attention after an injection ?
- Reduced or abnormal vision, weakness on one side of the body or difficulty speaking. Call 144 immediately. Explain that a hyaluronic acid injection has just been performed and state when the symptoms began. Do not wait for the follow-up appointment.
- Difficulty breathing, swelling of the tongue or throat, or feeling severely unwell. Call 144 immediately. These symptoms may indicate a severe allergic reaction.
- Unusual or increasing pain, skin turning white or becoming greyish, bluish or mottled. Contact the injecting doctor immediately for an urgent assessment. If they cannot be reached promptly, go to an emergency department without delay. A vascular complication can also begin without intense pain.
- Spreading redness, a warm and increasingly painful area, discharge or fever. Seek a prompt medical assessment on the same day. These signs may suggest an infection.
These warning signs are described in particular in the medical guidelines on vascular occlusion after injection and the FDA information on filler complications. In Geneva, the HUG state that the number for life-threatening emergencies is 144.
What rare complications can hyaluronic acid cause ?
Not all complications are associated with a technical error, and they are not all corrected in the same way. Managing them requires identifying the cause before deciding on treatment.
- Vascular occlusion. Product can block a blood vessel and reduce the blood supply to tissues. This can cause skin necrosis and, in certain situations, visual damage potentially leading to blindness or neurological injury. Prompt management is essential.
- Infection. It can cause painful redness, an abscess or discharge. Aseptic practice and sterile equipment reduce this risk.
- An allergic reaction. It may involve a product component, particularly lidocaine when present. A severe reaction requires immediate emergency assistance.
- Nodules and inflammatory reactions. Lumps, swelling or tender areas may develop, sometimes some time after the injection. A nodule is not necessarily a simple accumulation of gel ; its origin must be investigated before any correction.
- Irregularities, migration and colour changes. Excess volume, asymmetry, movement of the product or a bluish hue associated with a superficial injection, known as the Tyndall effect, may require medical advice.
Reactions appearing after several weeks or months are discussed on the page about delayed side effects of hyaluronic acid.
Which medical factors can increase the risks ?
Certain diseases, medications and medical histories may increase the risks associated with hyaluronic acid injections. A prior medical assessment identifies contraindications and necessary precautions.
An active infection or inflammation in the area to be treated requires the injection to be postponed. If there is a known lidocaine allergy, a hyaluronic acid without lidocaine must be chosen. During pregnancy and breastfeeding, aesthetic injections are deferred as a precaution because of the lack of safety data.
Other situations require particular attention :
- Clotting disorders and medicines that promote bleeding. They can increase bruising or bleeding. Report any anticoagulant or antiplatelet medication ; do not stop it without the prescriber’s advice.
- Diseases and treatments that alter immune defences. An autoimmune disease, hepatitis or immunosuppressive treatment require individual assessment. The diagnosis alone does not establish whether injection is possible or prohibited : disease activity, treatment and the product instructions matter.
- Previous injections or surgery. They may alter the anatomy of the area to be treated. The presence of a permanent product or one of unknown composition requires particular vigilance.
- Scars in the injection area. They may alter the tissues and require an adaptation of the technique.
How does the doctor reduce the risk of a complication ?
Preventing complications associated with hyaluronic acid injections relies on concrete medical choices before and during the injection. Several precautions are essential :
- Anatomical assessment. The doctor examines the area to be treated, identifies areas of vascular risk and considers any changes associated with surgery or scarring. They may decide against an injection when the risks are too high.
- The choice of product and technique. The type of hyaluronic acid, injection depth and quantities used must be adapted to each area. Injecting slowly, at low pressure and in small quantities helps reduce the risk of vascular occlusion.
- Aseptic practice. Skin disinfection, sterile equipment and compliance with the product’s conditions of use help limit the risk of infection.
- Prompt management of complications. The doctor must recognise the first signs of a complication, stop injecting immediately if necessary and arrange appropriate care. The patient must also be able to contact the practice after the session if an unusual symptom occurs.
These measures are described in the guidelines on the prevention and management of vascular occlusion. In Switzerland, Swissmedic also emphasises the importance of qualified professionals and compliant products.
Why avoid injections outside the authorised medical framework ?
In Geneva, the cantonal rules on aesthetic injections restrict injections to doctors or nursing staff working under direct medical supervision. For hyaluronic acid-based injectables intended to remain in the body for more than thirty days, nursing staff must have additional training in this field.
An offer at home or on social media does not, on its own, allow these conditions to be checked. A lack of qualifications, product traceability or means of managing complications exposes patients to avoidable risks. A needle-free device such as the Hyaluronpen does not make injection risk-free or remove the requirement for an authorised professional framework.
Conditions of practice are detailed on the page about professionals authorised to perform hyaluronic acid injections in Switzerland.
This page details medical dangers and warning signs.
