Treatment for dark horizontal line on nose? (Photo)

It looks like there is an actual crease or indentation that could be addressed with either a Juvederm or some type of filler that would lessen it being so noticeable.  You may want to try this, it's not permanent but if you like the results you can continue with it.  Best of Luck to you! 

Thank you for your question!There are a few options that are offered. These marks can be improved with a combination of Cosmelan, lasers, Aerolase, microneedling(RF/)/prp, skin lightening, peels, and skin care. Sun protection is essential. I recommend getting a formal evaluation with a scarring expert. Best, Dr. Emer

A filler may be an option for the line across your nose depending on what the cause of the line may be.  An evaluation by a physician would be necessary to determine this.  As far as the discoloration of the area you may need a chemical peel or laser treatments to the area to address the darkness.  Once again you should visit a physician to see what treatment options are best to help you meet your goals.

This is a great question. You mentioned that you have allergies. A horizontal crease on the nose is a characteristic sign of allergies and is termed “allergic salute”. It is caused by upward rotation of the nose when wiping or rubbing to relieve the itching. The darkness may be Post inflammatory hyperpigmentation or PIH. It will be important to stop the cause before treatment (treat the allergies  to stop the manipulation). Without that, attempts to soften the crease or fade the color will be  limited. 

Hi there thank you for your question. 
Treatment depends on what is causing the line. For example, it may be due to pigmentation or a physical hollow.
Dermal filler may be used to improve a physical hollow with careful placement of hyaluronic acid based product. 
Make sure you see a trained and highly experienced aesthetic practitioner for review of this. 
Hope this helps!
Dr Rupert

It is best to analyze what characteristics of this line make it more noticeable.  Treatments to lighten dark pigmentation include topical bleaching creams, chemical peeling, or laser resurfacing (fraxel or pulsed dye lasers).  The depression itself may create a shadow effect, making the skin look darker.  Filling in the depressed line with a hyaluronic acid filler such as Restylane or Juvederm, may help minimize visibility for a year or two and create a smoother skin surface that looks better.  Any of these treatments are worth a try, easy to go through, and should help.