Most people do not report severe side effects after receiving collagen injections; however, the outcome varies by person. More common side effects include slight bruising, as well as puffiness and redness around the injection site. Your doctor may ask about your use of substances like alcohol, aspirin, green tea and St. John's wort before you undergo a collagen injection because using these substances before treatment can increase bruising at the injection site [source: American Academy of Dermatology].
There are no restrictions on activities after receiving a collagen injection, and makeup can even be applied directly over the injection site [source: American Academy of Dermatology].
If your doctor is considering using a non-biodegradable filler, you'll likely have to undergo allergy testing before treatment to determine whether the procedure is suitable for you. Otherwise, you could have a severe reaction. To screen for allergies, the doctor will test your skin by injecting your arm with a small amount of the substance. During the next four weeks, you'll watch to see if there's an allergic reaction at the injection site [source: MedicineNet]. Such reactions are uncommon. Overall, soft tissue fillers are considered safe and effective by dermatologists [source: American Academy of Dermatology].
If you experience unusual side effects after undergoing any kind of collagen treatment, you should consult a physician immediately.
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