The effect of injections with a hyaluronic acid filler can be seen immediately, as soon as the skin irritation resulting from the injection has died down. The effect normally lasts for three to six months, and even up to 12 months in some cases. The time the effect lasts for depends on the preparation used, the disposition of the patient, the region of the face and whether these regions had previously been relaxed and prepared using botulinum toxin.