Caffeine in moderation can be a good thing.

Studies have shown that caffeine intake can help increase well-being, happiness, energy, alertness and sociability. Once you exceed 2-3 cups of either tea or coffee however,you might experience symptoms like migraines, palpitations, nervousness, rapid heartbeat and jitteriness. Caffeine can increase bladder activity and result in exacerbated symptoms, including higher urgency and frequency of urination, as well as increased incontinence.

Caffeine can also interfere with the compound in your body that helps you fall (and stay) asleep.

It is recommended you stop you caffeine intake no later than 3pm.

How does caffeine affect your skin?

But what about the effects of coffee and tea on our skin? Caffeine is a dehydrator, similar to alcohol and sodium, and when our bodies lack all important hydration, it can show up on your skin, too.

And acne? While coffee itself doesn't cause acne, some studies suggest caffeine can make it worse by increasing inflammation and stimulation of cortisol. This stimulation may increase inflammatory hormones and oil production exacerbating acne breakouts. It can dehydrate the skin, making it more unbalanced. An unbalanced microbiome is more prone to infection, also causing more breakouts.
In addition to caffeine, what you add to your coffee may also have an effect on your skin.

Key ingredients of a cup of coffee or tea include milk and sugar, two of the top four dietary acne triggers making skin more prone to breakouts.

Dairy
For latte lovers, milk could be affecting your skin too, as there's enough evidence to strongly suspect that dairy milk plays a role in acne – especially seen around the mouth and jawline area.
Non-organic dairy products also have large amounts of hormones and antibiotics.

Sugar
Chances are, unless you are drinking plain black coffee, your cup will contain sugar and that too can be affecting your skin. Excess sugar in your bloodstream can cause Glycation, a natural chemical reaction which happens when sugar levels in the bloodstream spike beyond what our insulin can handle. Glycation affects the part of our skin that keeps it ‘springy’ – the collagen and elastin, and permanently breaks it down. We used to think glycation could somewhat be reversed, but studies are showing otherwise. A pound of prevention.... When skin proteins link with sugars they become weaker, and when these essential skin building blocks are impaired, and the signs of aging become more apparent.

Foundational structures such as elastin and collagen becomes drier and less elastic, resulting in wrinkles, sagging and a dull skin appearance. Besides white sugar, the flavor syrups (sugar/artificial colors/artificial flavors/preservatives) can negatively affect your hormones and lead to acne.
(Yup, that means scale back on your fancy, sugary Starbucks concoction).

Poor quality coffee, especially if consumed with dairy products sourced from cows injected with antibiotics, can disrupt gut flora. Organic coffee has not been associated with gut flora disruption. But why exactly is gut flora important? As Dr. Bowe explains it, if your gut is inflamed, that will show up as inflammation in your skin. Inflammation ages akin. "Eating the wrong types of foods, unfortunately, slows down digestion and creates a shift in the type of bacterial environment in your gut," Dr. Bowe says.

"It affects your gut microbiome, and that, in turn, leads to leaky gut,and leaky gut translates to leaky skin."

Benefits
Did you know that coffee and tea extracts can also be powerful skin care ingredients? Anti-oxidants found in green tea extract have been shown to have anti-ageing properties, and caffeine is used in some brightening and firming skincare products. (However, caffeine is dehydrating & its so-called firming-effects are only temporary.) Although the effects are short-term, Dr. Goldenberg says the caffeine in topical products can decrease the appearance of cellulite by dehydrating the tissue. Bowe adds that coffee grounds also work reduce swelling and puffiness, which is why you'll commonly find this ingredient in eye creams and treatments.

If you're a big-time coffee and tea drinker, good news: they my be a good source of certain antioxidants. You might be familiar with free radicals, but for the uninitiated, they're the damaging molecules that cause premature aging, and according to some studies, they can even lead to acne. In other words, free-radicals are the skin enemy.

THIS is the reason I believe everyone should be on certain topical and internal antioxidant supplements. Antioxidants work to fight free-radical damage. Bowe recommends that her patients who are particularly prone to breakouts up their intake of antioxidants.

The FDA suggests a maximum of 400 milligrams of caffeine a day.

In my opinion, even that amount is very excessive.

With excerpts from Dermatologists: Whitney Bowe, MD; Gary Goldenberg, MD