Re-Dye Hair

Woman who wants to re-dye her hair
Photo: Elnur/Shutterstock
Q: I just dyed my hair last night. Can I dye it again today? That would be after less than 24 hours. If not, how long should I wait?
 
A: You can, provided that your hair and your scalp can withstand a second chemical process.
 
If you are specifically planning to use a deposit-only color (such as a semi-permanent color or direct dye with no developer), you should be pretty safe. Semi-permanent deposit-only colors coat the outside of the hair shaft rather than lifting your natural pigment, so they cause virtually no damage. However, if you use a demi-permanent color requiring a low-volume developer, keep in mind it still slightly opens the cuticle, and dryness can occur.
 
With color processes that lift the color (like bleach or high-lift permanent dyes), you have to be very careful, or you seriously risk severe hair damage and scalp irritation. Permanent hair color and bleach work by opening the hair cuticle and altering the hair's natural pigment.
 
Subjecting your hair to this process twice in 24 hours can strip away essential lipids, leaving your hair dry, brittle, and prone to severe breakage. And double-processing can cause chemical burns, redness, or extreme sensitivity on your scalp, which needs time to replenish its natural protective oils.
 

Darkening, Lightening, and Dye Buildup

If your goal is simply to darken your hair or correct an uneven result, a second application of deposit-only dye may be appropriate. But beware of dye buildup: layering permanent dye over freshly colored hair can cause the ends to look muddy or significantly darker than intended.
 
If you are trying to go lighter than your current shade, do not apply another round of permanent dye expecting it to lift. Dye cannot lift existing dye. Lightening already-processed hair requires lightener (bleach) or a color remover, both of which require extreme caution on freshly processed hair.
 

Safety Testing Before You Re-Dye

If there is any question whatsoever, perform a strand test and a patch test first:
 
• Strand Test: Take a small lock of hair from an inconspicuous area (like near the nape) and apply your mixed color formula for the full processing time. Rinse it, wet it again, and gently pull on a few strands. If the hair stretches and doesn't snap back, or if it feels gummy, mushy, or breaks off easily, your hair structure is compromised and cannot handle another process.
 
• Scalp Care: If your scalp feels tender, itchy, or burnt from yesterday's session, wait at least a few days to a week before applying anything else.
 
If the strand test is successful - and your hair still feels smooth, strong, and healthy - you can proceed at your own risk. If you do notice mild dryness, incorporate a bond-repair treatment or deep-conditioning mask before attempting any further coloring.
 
If you are uncertain about your hair's condition, are dealing with severe damage, or are attempting a major color correction (like going from dark back to blonde), hold off and consult a professional colorist. They can evaluate your hair's porosity and elasticity to recommend the safest path forward.
 
©Hairfinder.com
 
See also:
 
How to color hair
 
Signs of hair damage
 
How often can I color my hair before I destroy it?