An Overview of Caffeine Sensitivity

Caffeine intolerance symptoms can occur when you experience an overreaction to coffee and other caffeinated beverages or foods. With caffeine sensitivity, the adverse symptoms after consuming caffeine include headaches, jittery feelings, diarrhea, and insomnia.

These symptoms can occur when anyone drinks too much coffee, but caffeine sensitivity is a heightened response that occurs at typically smaller doses. Caffeine sensitivity is not a caffeine allergy, which would be an immune response to caffeine.

This article explains what caffeine sensitivity is and how it differs from an allergy. It also describes how caffeine sensitivity is diagnosed and how to cope if you are suddenly forced to quit caffeine.

Caffeine Sensitivity Symptoms

It may be hard—both for you and your healthcare provider—to immediately identify caffeine as the source of your symptoms and determine whether caffeine sensitivity is involved.

Caffeine works by suppressing a chemical called adenosine that helps you sleep and by increasing the production of adrenaline, which gives you a burst of energy.

In people with caffeine sensitivity, the body's response to these chemicals is amplified, causing symptoms such as:

• Jitteriness or shakiness
• Headaches
• Heart palpitations (skipped beats)
• Diarrhea and other digestive disorders
• Insomnia and/or fatigue
• Anxiety
• Irritability and restlessness
• Urinary urgency (needing to rush to the bathroom to pee)
  

Causes of Caffeine Sensitivity

People's level of sensitivity to caffeine are to caffeine may be due to genetics, at least in part. One study of the CYP1A2 enzyme responsible for caffeine metabolism found a genetic link to explain why 54% of people studied were slower at processing caffeine in their bodies, while about 46% were fast metabolizers.

But many other factors can affect your caffeine sensitivity, too. They include:

• Your age and sex
• Hormone activity
• Liver disease
• Obesity
• Smoking
• Diet

Caffeine also interacts with many medications. Methotrexate, a drug used to treat numerous rheumatologic and oncologic diagnoses, may be affected by caffeine intake. Caffeine also may be included in a drug, as is the case with the pain reliever Excedrin.

Caffeine sensitivity is not an allergy, which would be an immune system response to caffeine.

Diagnosis

Caffeine sensitivity is hard to pinpoint because its biological mechanisms are poorly understood. To reach a diagnosis, a healthcare provider would need to exclude all other possible causes.

If you are suddenly sensitive to caffeine, your symptoms may be due to other substances used in the making of the product. Some people find, for instance, that they are sensitive to light-roasted coffee beans but not dark-roasted beans. Others have a reaction to molds that can grow on coffee beans. Speak with your healthcare provider, as sudden food sensitivities should never be ignored.

If all other causes have been excluded, including food intolerances, then your provider may reasonably assume that food sensitivity is involved, particularly if the symptoms are not severe.

Treatment

The main treatment for caffeine sensitivity is cutting all caffeine out of your diet. This may include beverages and foods like:

• Black, green, and white tea
• Colas and energy drinks
• Chocolate, cocoa, or cacao
• Certain headache medications (like Anacin)
• Over-the-counter stimulants (like NoDoz)

According to the Food and Drug Administration (FDA), up to 400 milligrams (mg) a day of caffeine is a safe amount. That’s equal to about 4 cups of coffee. However, your response to caffeine can vary based on your weight, age, and individual sensitivity to caffeine.

You may be dose-sensitive, meaning that symptoms only occur at certain higher doses. In some cases, all you may need to do is cut back on caffeine rather than cutting out all caffeine.

Often, older people become more sensitive to certain effects of caffeine; one reason may be the slower metabolic clearance time for caffeine. The liver takes longer to break down caffeine, leaving more of it to build up in the body for longer periods. Medications also can affect this process.

If your symptoms are not serious, you can see how you respond to different forms of caffeine on a trial-and-error basis. Speak with your healthcare provider first just to be safe.

Coping

Quitting caffeine is easier said than done. Caffeine withdrawal can cause headaches, fatigue, and irritability. You may even experience nausea and flu-like symptoms. These symptoms typically start within 12 to 24 hours of stopping caffeine and can take between two and nine days to fully subside.

You can do several things to wean yourself off caffeine with the least amount of stress:

• Rest: If you're used to drinking a lot of caffeine, stopping may cause you to "crash" for a couple of days. You can prepare for this by setting aside time for extra sleep and relaxation.
• Drink water: Drinking plenty of water throughout the day can reduce your craving for cola or caffeinated energy drinks.
• Exercise: Taking a long walk or exercising can counteract fatigue. Fresh air may give you a much-needed boost when your energy starts to lag.

Alternative Drinks for Caffeine Sensitivity

If coffee is part of your morning ritual, you can replace it with a hot, non-caffeinated beverage such as:

• Herbal tea
• Warm apple cider
• Hot water with lemon
• Caffeine-free roasted chicory coffee

Summary

Caffeine sensitivity occurs when you are overly sensitive to the effects of caffeine, causing jitteriness, headaches, diarrhea, and other symptoms.

Caffeine sensitivity is diagnosed based on the exclusion of all other causes. The main treatment is the avoidance of caffeine.

Giving up caffeine can lead to withdrawal symptoms. You can ease them by replacing coffee with a non-caffeinated beverage, drinking lots of water, and getting ample rest and exercise.

A Word From Verywell

When used in moderation, the effects of caffeine—such as increased alertness—can be beneficial. But, if you're one of the rare people with caffeine sensitivity, you'll need to turn to other forms of stimulation to give yourself a boost.

One tried-and-true method is exercise. Something as simple as a brisk walk can spur the release of "feel-good" hormones called endorphins that not only amp up your energy levels but your mood as well. And, unlike a cup of coffee, the effects are absolutely free.

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