Hyaluronic Acid Injections: Side Effects, Risks and What to Expect Afterwards

• Expected: redness, swelling, tenderness and bruising shortly after the injection; many of these reactions go away within a few days to a few weeks, and this varies from person to person.
• Have these assessed: a lump, a reaction that appears weeks or months later, a bluish tint that persists, a result you are not satisfied with.
• Seek care right away: unusual or increasing pain, white, grey, blue or mottled skin, a change in vision, a sign of stroke such as weakness on one side, fever, an area of redness that feels warm and is spreading, pus or a severe allergic reaction.
• Before the injection: mention your allergies, your treatments and your medications; the safety of fillers has not been established during pregnancy or breastfeeding.
• Avoid: needle-free injections at home, and massaging the area without instructions from the person who injected you.

A few hours after a hyaluronic acid injection, the area is red, swollen and tender, and you are wondering whether this is normal. Or you are hesitant to get one, and what you hear about fillers worries you. A hyaluronic acid injection places a gel, known as a dermal filler, in or under the skin. It has side effects that a skin care product applied to the surface does not have; the hyaluronic acid in a serum, with its benefits and limitations, serves a different purpose. Redness or swelling can be among the after-effects of the injection. A lump or a delayed reaction warrants medical advice; some signs, such as unusual pain or a change in vision, require immediate care.

After a filler treatment, the area can be red, swollen, tender or bruised. These reactions usually appear shortly after the injection, and many subside within a few days to a few weeks. Some last longer. How long they last varies from person to person: this timeframe alone is not enough to tell whether your skin is recovering normally.

Having these reactions is not enough to conclude that everything is progressing normally. Unusual or increasing pain, an area of redness that feels warm and is spreading or a change in skin colour are not among the expected reactions.

If your question is about lip swelling, ask what to expect after a lip injection and which signs should prompt you to seek care.

After an injection, the area may show marks and remain tender for a while. Follow-up is necessary, and the result is not guaranteed: it depends on the structure of the tissues, the amount of gel and the type of filler. Dermal fillers are not a single type of product, and they do not all behave in the same way. If you are not satisfied with the result, reducing or removing a filler may require injections, surgery or other procedures, which carry their own risks.

A bump can appear in or under the skin after a filler treatment. This is called a nodule; a granuloma is a specific type of reaction, not a term for every lump. Not all lumps are granulomas: a true granuloma can only be confirmed by examining a tissue sample under a microscope; neither feeling the lump nor looking at a photo can confirm it. An inflammatory lump can result from the body’s reaction to the gel, a delayed immune reaction or an infection. These reactions can appear weeks, or even more than a year, after the injection. Inflammation near the injection site can also follow a viral or bacterial infection, a vaccination or dental treatment.

A lump that grows, or a reaction that appears long after the injection, should be assessed by a doctor. The doctor looks for the cause before deciding whether a prescribed treatment is necessary. Do not try to treat the lump yourself.

Redness, swelling, pain and warmth can signal an infection; fever can accompany it when the infection is more severe. Redness or swelling can be among the after-effects of the injection, but an area of redness that feels warm and is spreading, unusual or increasing pain, fever or pus require an assessment without delay. An infection that is initially limited to the treated area can spread if it is not treated. If there is pus, do not try to drain the area or treat it at home: contact the person who injected you immediately for an assessment.

A severe allergic reaction, with anaphylactic shock, requires immediate emergency medical help.

A bluish tint visible in the skin is sometimes caused by hyaluronic acid gel placed too close to the surface or deposited in a large amount in one spot. Doctors call this the Tyndall effect. This tint can be mistaken for a bruise; they cannot be told apart by colour alone.

During or shortly after the injection, skin that turns white, grey or blue near the injection site is a very different signal: it is an emergency sign. A bluish tint that develops later can have several causes, including gel placed too superficially, and should be assessed.

The most serious risk is unintentional injection of the gel into a blood vessel: the vessel becomes blocked (vascular occlusion) and the tissues receive less blood. This risk is unlikely, but its consequences can be serious and permanent: tissue death (necrosis), vision problems up to and including blindness, or stroke. Pale, dark or mottled skin, with a net-like pattern of discolouration, requires immediate medical care. Correcting a problem with the gel does not guarantee that the consequences of a complication can be avoided or undone.

Before a filler treatment, discuss any allergies, bleeding disorders, heart problems, cold sore outbreaks and previous cosmetic treatments, including other injections and implants. Also mention all your medications, even those available without a prescription, as well as your vitamins, minerals and herbal products. Do not stop taking a medication on your own: this is a question for the doctor who prescribed it.

Infected or inflamed skin (pimples, cysts, rashes, hives) may lead to the injection being postponed until the skin problem has been addressed. A bleeding disorder is also a reason to discuss postponing the filler or deciding against it. The doctor may therefore offer, postpone, modify or decide not to perform the injection, depending on your situation.

The safety of fillers has not been established during pregnancy or breastfeeding. Tell the doctor if you are pregnant or breastfeeding: this uncertainty is a factor in the decision. Your age is also part of the assessment; the product’s conditions of use must be checked before the injection. The fact that hyaluronic acid is naturally present in the skin does not prove that it is safe.

Before the injection, ask for the instructions that apply to the product you will receive, taking your situation into account. Also ask whom to contact if a problem arises.

A disappointing result is not always a complication, and expected discomfort is not a failure. The result depends on the tissues, the amount of gel and the type of filler, and a photo is not enough to tell what is happening under the skin. The doctor examines you to look for the cause and to determine whether further tests are necessary. The doctor then decides whether to wait or to treat.

After the assessment, the doctor may offer a prescribed treatment that dissolves the gel. For gel placed too close to the surface, the correction may target only the superficial deposit. The choice takes into account what you want — removing all the gel or correcting only the tint — and what is possible based on the assessment. Dissolving the gel can mean losing the entire aesthetic benefit of the injection. To correct gel placed too superficially, a second session is sometimes necessary. There is no guarantee that the correction will be complete. Any complication is managed by a doctor.

Never inject yourself with filler, and do not use a needle-free pen. These devices propel the product at high pressure and do not adequately control where the gel ends up. They have been associated with scarring, skin discolouration, infections and other unexpected effects. A product being sold online or trending on social media does not make it safe: it can cause serious injuries.

At CARE MD, in Sainte-Thérèse, on Montreal’s North Shore, hyaluronic acid injections are performed by a doctor or by a nurse injector supervised by a doctor; any complication is managed by a doctor. You can learn about our professionals before your appointment. Choose someone experienced and take the time to understand the possible risks and benefits before deciding. You can ask these questions:

• What training and experience does the injector have?
• How do they recognize an injection into a blood vessel, and what is their plan to treat you if it happens?
• What are the risks in your situation, given your medical history?
• How can you reach them after the injection if something worries you?

An urgent situation requires immediate care. Do not wait for a response to this form.