One of the more unwelcome signs of aging may be the skin's propensity to sag. Fortunately, modern technology, including laser resurfacing and radiofrequency therapy, have come to the rescue to help return firmness to mature skin, according to the American Academy of Dermatology, or AAD. Some people may choose to undergo the more traditional face-lift. This invasive procedure may be the most effective and longest lasting solution to sagging skin. All skin firming treatments have at least minimal side effects such as bruising, redness, swelling and possible discomfort. More serious side effects like permanent discoloration or scarring are also possible.

During ablative or wounding laser resurfacing, the outer layer of skin known as the epidermis is destroyed while heat that penetrates the deeper layer of skin called the dermis. This encourages the growth of new collagen. The result is smoother and tighter skin, according to the Mayo Clinic.

The potential side effects of ablative laser resurfacing include skin redness, dryness, infection, scarring and irregular pigmentation such as lighter or darker spots. The full healing process may take several months.

Less intense lasers or non-ablative devices help stimulate new collagen without harming the epidermis, according to the AAD. This type of laser therapy for skin tightening has minimal healing time.

Apart from a brief reddening of the skin, few if any side effects are reported with non-ablative lasers. However, the daily use of certain medications such as aspirin or anti-inflammatory medications may hamper the full potential of this type of laser therapy.

Non-ablative lasers may not be advisable for people with dark skin since it may cause lightening of the skin called hypopigmentation, according to Plastic Surgery Adviser.com.

Radiofrequency devices, such as Thermage and Thermacool, work beneath the surface layer of the skin to promote collagen growth and tightening without damaging the epidermis.

The procedure may cause some discomfort and recovery typically takes up to one week or longer. During this time patients may experience skin redness, swelling, and possible blisters. Pain may persist for several days following the procedure.

A face-lift is an invasive procedure that improves sagging by removing excess skin and fat and tightening the underlying facial muscles and connective tissue, according to the Mayo Clinic. The results of a face-lift may last up to 10 years.

Bruising and swelling may linger for several weeks following this surgical procedure. Some patients may experience temporary facial or ear numbness. In rare cases numbness or skin discoloration can be permanent.