Caution- Topical caffeine affects the whole body and too much on your skin is the same as too much when ingested. Larger concentrations can be dangerous. If you're caffeine-sensitive, topical caffeine might keep you awake if you use caffeine in products at night, or give you a "caffeine buzz" during the day. 

Caffeine stimulates hair growth and quickly-absorbed to increase blood flow in the scalp. Caffeine does not need to stay on the scalp until the next washing (that's why shampoos work), but it does need about 2minutes to absorb into your skin before rinsing

Caffeine may slow down excessive shedding and stimulate hair growth.

Topical caffeine has been measured to stay active in hair follicles for up to 48 hours, so it needs to be used every 1-2 days to be most effective.

DIY caffeine recipe: Here are 2 options.

Option 1) Lower concentration, ready to use without further diluting - but dilution may be a good idea:

Mix the contents of one-fourth of a 200 mg capsule of caffeine powder (such as this one with no fillers or additives) with 1 gallon (about 4 liters)distilled water.  Using too much caffeine can cause the same side effects as ingesting too much caffeine, or can cause scalp irritation. Overdosing on caffeine can be very dangerous for people of any age! ©Science-y Hair Blog 2017 

The end concentration is approximately 1.25% to 1.3% with this mixture. I recently updated this concentration due to a arithmetic error.  This is more concentrated than necessary - but we're working with really small amounts that require much more sensitive equipment than most of us have!

I encourage you to dilute this before using it. Use 1part caffeine-water, 3 parts water or shampoo or whatever you are adding the caffeine water to.

The caffeine-water could be mixed with a shampoo (when using, don't dilute a product in its bottle), or made into a spray or put in or in a dropper-bottle to apply to the scalp.

Option 2) Higher concentration, needs to be diluted to use: Add the contents of a single, 200 mg capsule of caffeine powder (with no additives) to 1 gallon (about 4 liters) distilled water. This is your highly concentrated solution. Dilute this solution to make sprays or scalp" drops" or to add to a shampoo by using 5% to 10% caffeine solution in your product. For example, 5 grams caffeine solution per 100 grams total product is 5%. To be exact, 5% caffeine solution + 95% "everything else"= 100%. I make shampoo and a leave-on scalp gel this way.

Can brewed tea or coffee be used? Yes. But not decaffeinated tea or coffee. Tea and coffee can create or enhance "cool" or ashy tones in hair. The tea or coffee needs to contact your scalp and be left on for at least 2 minutes.

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