Can I keep using Tri-luma but reduce the use after get the halo effect?

Melasma and age spots can be due to hormones, aging, sun exposure, thyroid dysfunction, and genetics. Treatments range from IPL to laser therapy; but pigmentation may recur if not complemented with topical creams to stabilize the pigment cells.
I would suggest starting with Melarase Brightening Kit with Melaclenz, Melapads, Melarase AM, and Melarase PM to help stabilize pigmentation and reduce recurrence. Once started, an active protocol that includes Covalent peels, IPL, fractional laser, and microneedling can further remove pigmentation.
Best, 
Dr. Karamanoukian
Realself100 Surgeon

Good afternoon and thank you for your question! Because TriLuma has hydroquinone in it we do not recommend spot treating with it. We advise using TriLuma over the entire face and then going back over with extra on the hyperpigmented areas to avoid the halo-effect. Be sure to use sunscreen daily when using bleaching cream! Best of luck! For more information please feel free to visit our website!

Best to stop as the HQ will further bleach the surrounding skin. Accurate placement coupled with accurate laser can reduce the HALO effect. The lightening of the surrounding skin can easily be regimented. The idea is to accurately fade the areas of hyper pigmentation, with as little collateral damage to the surrounding skin- hence why I like lasers to 'trace'. 
Melasma is a very common cause of skin pigmentation. It can not be completely cured, however effective treatment are possible. This is because your skin is extremely sensitive to UV and even the smallest amount can stimulate your pigment cells to produce colour. The mainstay of treatment is strict UV protection- hats, sunglasses and SPF every 4 hours. This forms the foundation of all treatments. 

I prefer to use a combination of creams and laser for melasma. Hydroquinone can be used (5-8%), along with vitamin A creams or Meladerm. I start my patients on laser (low dose Q switch or Picosure) as this has shown to decrease pigment production by decreasing the activity of the cells that produce pigment. Laser itself is not aimed at ‘blasting’ pigment, but to slow down the rate of melanin production. Another laser I use is the Clear and Brilliant in the 1927 Permea setting combined with creams. IPL should never be used to treat mixed melasma as it often worsens the condition (this is termed ‘Rebound Melasma’) 

In some cases I combine glycolic AHA peels, and in other cases I use a tablet called Tranexamic acid to help. Melasma treatments should be tailored to each patient according the type of melasma. Majority of patients will have mixed dermal and epidermal melasma. Approach melasma as a medical condition and not a cosmetic concern, and the success rate will be much higher. 

Consult a Board Certified Laser dermatologist with a special interest in disorders in pigmentation as well as one who has experience in treating all skin types, including darker Ethnic skin. 

All the best, Dr Davin Lim. Laser, surgical and aesthetic dermatologist. Brisbane, Australia.