How to Prevent Bruising from Fillers?

Besides avoiding aspirin, ibuprofen, fish oil, etc. for 1-2 weeks prior to a filler treatment I recommend Cearna Ocumend hydrogel pads immediately after filler treatments.  These deliver a very high, concentrated dose of Arnica Montana directly to the areas where it is needed.  In my experience it reduces bruising significantly, especially in those people who tend to bruise frequently.

Thank you for the question. There are steps that can be taken to reduce the swelling and bruising.  
Before the treatment, it is advised that you avoid medications and substances that increase the risk of bruising.  The patient may be asked not to take aspirin or NSAIDs for at least 7 days, unless discontinuation of these poses a significant risk.  Herbal medications (such as St John’s wort, ginkgo biloba, vitamin E, garlic, ginseng, fish oil) that predispose to bleeding and bruising should be withheld.  Preoperative ingestion of some homeopathic medications such as arnica may reduce bruising, although further investigations are needed to confirm this.
It is also imperitive that you choose an experienced injector who uses a technique to minimize bruising.  This is an operator dependent procedure and so you need to be in safe hands.
After the procedure I also advise my patients to ice the area for up to 10 minutes every hour.  Reusable ice packs can be used or a bag of frozen peas can be used to mold over the area.  A short course of steroid can also accelerate the healing process.  Anectotally, Arnica forte can be used to prevent bruising, but no definitive evidence exists to suggest that is always successful. 
If you would like to learn more about injectable fillers I recommend an in person consultation with a board certified dermatologist with cosmetic training.

The method of injection is a major contributor to bruising. Medications and lifestyle choices can also contribute. You should choose an experienced injector, as well as avoid taking medications and supplements that promote bleeding (thin the blood), such as aspirin, St John’s Wort and Vitamin E. Start taking Arnica a week or two before your treatment, and continue taking it afterwards. Avoid vigorous physical activity and hot baths on the day of your treatment, as well as a day or two afterward. You should also avoid smoking.