Caffeine Withdrawal Timeline: Hour by Hour

General information, not medical advice. If you have a health condition, are pregnant or breastfeeding, or take medicine that interacts with caffeine, talk to your doctor before changing your intake.

Disclosure: FizzFree is made by Etest Tech Hub, the company that publishes this site and is led by the author. This guide is written to be useful without the app, and every figure is attributed to its source below.

This post sets out the timeline from the best review we found, shows how much caffeine is in a can of soda, and explains how to plan around it.

The short version

Based on a widely cited 2004 review of the research:

• Onset: about 12 to 24 hours after your last caffeine.
• Peak: about 20 to 51 hours after.
• Duration: about 2 to 9 days.

Those are typical figures from experimental studies, not promises. In general, heavier daily intake meant more frequent or stronger symptoms.

Where these numbers come from

The timeline comes from a review published in Psychopharmacology in 2004 by Laura Juliano and Roland Griffiths. They analyzed 57 experimental studies and 9 survey studies on caffeine withdrawal. In the abstract they write: "Typically, onset of symptoms occurred 12-24 h after abstinence, with peak intensity at 20-51 h, and for a duration of 2-9 days."

In the experimental studies, the incidence of headache was 50%, and the incidence of clinically significant distress or functional impairment was 13%. The review also found that abstaining from doses as low as 100 mg a day produced symptoms.

Two honest limits. First, the data come from a review of studies, many of them short experiments where people were asked to stop on purpose. Second, the review is more than twenty years old, and we have not reviewed newer research that might refine the ranges. The ranges are wide for a reason: people differ.

Hour by hour, as far as the evidence goes

"Hour by hour" is a useful way to think about it, as long as you read the hours as windows, not exact times.

Hours 0 to 12. Caffeine is still clearing. Cleveland Clinic reports that effects can be felt about 15 minutes after you consume caffeine, blood levels peak about an hour later, about half is still in your body six hours later, and it can take up to 10 hours to clear fully. Because the typical onset of withdrawal is 12 to 24 hours, symptoms are usually not established in this window, though people differ.

Hours 12 to 24. This is when symptoms typically begin. Headache and fatigue are among the symptoms the review validated.

Hours 20 to 51. This is the usual peak, roughly your second day. Headache, fatigue, low mood, trouble concentrating and irritability are among the validated symptoms.

Days 3 to 9. Symptoms usually fade. The upper end of the reported range is 9 days. A small share of people may take longer, so if yours last longer than you expected, check in with a doctor or pharmacist.

What symptoms count as withdrawal

The review examined 49 symptom categories. Ten met its validity criteria: headache, fatigue, decreased energy or activeness, decreased alertness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, and feeling foggy or not clearheaded. Flu-like symptoms, nausea or vomiting, and muscle pain or stiffness were judged likely to be valid too.

The authors concluded there was enough evidence to warrant listing caffeine withdrawal as a disorder in the DSM, and it now appears in DSM-5. You do not need a diagnosis to quit soda. The point is that these symptoms are well documented, and feeling them does not mean you are weak or that quitting is a bad idea.

How much caffeine is in your soda?

The size of any withdrawal depends on how much caffeine you were taking in, from all sources. Here are figures from authoritative sources.

Two things stand out. A can of soda usually has less caffeine than a cup of coffee, so a one-can-a-day drinker may have a milder experience than someone on three coffees a day. And diet cola is not caffeine-free. Check the label on whatever you drink, because brands and countries differ.

How we converted the USDA numbers: USDA lists caffeine per 100 grams. We multiplied by about 3.55 to estimate a 355 mL can, which assumes 1 mL weighs about 1 g. Real cola is slightly denser, so the true figure is a little higher.

Daily limits for context

• The FDA cites 400 mg a day as an amount not generally associated with negative effects for most healthy adults.
• The NHS says pregnant women should have no more than 200 mg a day.
• Both numbers count all caffeine together: soda, coffee, tea, energy drinks, some medicines and pre-workout powders.

If you are pregnant, trying to conceive or breastfeeding, ask your doctor or midwife about your own limit.

Symptoms and what clinics usually suggest

This is a summary of public guidance from clinics, not treatment advice.

• Cut down slowly. Cleveland Clinic and Mayo Clinic both advise reducing caffeine gradually rather than stopping abruptly, to avoid withdrawal symptoms.
• Know your real intake. Cleveland Clinic says caffeine turns up in coffee, tea, chocolate, protein drinks, supplements and medicines, and advises reading labels.
• Drink water. Cleveland Clinic notes dehydration often causes the low energy people try to fix with caffeine.
• Set a cutoff time. Cleveland Clinic mentions about 2 p.m. as a cutoff that protects sleep.
• Swap the ritual. For soda cravings, Cleveland Clinic suggests sugar-free seltzer. Caffeine-free herbal tea is another option many people use.
• Be careful with caffeinated painkillers. Cleveland Clinic advises against using them for withdrawal headaches because you are feeding the dependency in a different way. Ask a pharmacist about any medicine you take.

For headaches that are severe or unusual, see the NHS headache guidance listed in the sources below.

Taper or cold turkey?

Cold turkey means stopping completely. A taper means stepping down over days or weeks.

The consistent advice from the clinics we read is to cut down gradually. What we could not find is a trial that directly compares the two approaches for soda drinkers. The case for tapering rests on how withdrawal works (a smaller drop in caffeine each day) and on clinical advice, not on a head-to-head result. So tapering is a sensible default, and cold turkey is a valid choice if you accept a rougher stretch of a few days. If you are unsure, talk to a doctor or pharmacist.

If you choose to taper, our 14-day plan to quit soda lays out one way to do it.

Soda is not only caffeine

When you quit regular soda you also drop a lot of sugar. The CDC says a 12 ounce regular soda has about 42 grams of added sugar. Some of what you feel in the first week may be habit and routine rather than chemistry. We found no strong evidence that sugar alone causes a distinct withdrawal syndrome, so we do not claim it.

Tracking your own timeline

A simple log makes the pattern visible. Note the time of your last caffeinated drink, then jot down how you feel at roughly 12, 24 and 48 hours. You will see your own onset and peak, which is more useful than any average.

Our app, FizzFree, tracks your soda-free streak and the money, sugar and caffeine you skip. It includes a health timeline and a 60-second Craving SOS. It is a habit tracker, not medical advice. You can read about it on the FizzFree quit soda app page.

When to see a doctor

• Symptoms are severe or last longer than you expected.
• You are pregnant or breastfeeding.
• You take regular medicine, or you have a heart condition, anxiety disorder or sleep problem.
• Headaches keep coming back or get worse.

Get emergency medical help right away (in the US call 911; in the UK the NHS says call 999) for a headache that starts suddenly and is extremely painful, or that comes with a stiff neck and very high temperature, numbness or weakness, confusion, trouble speaking, loss of vision, a seizure, or a rash that does not fade when pressed with a glass.

Track it with FizzFree

Log your soda-free days and see your streak in FizzFree, free to start on iPhone and Android. Learn more on the FizzFree quit soda app page. FizzFree is made by Etest Tech Hub and is a habit tracker, not medical advice.