Caffeine is a naturally occurring stimulant that causes arousal of the nervous system. For people with bipolar disorder, consuming caffeine can have unexpected and problematic consequences.

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Consuming caffeine is a regular part of many people’s everyday routine. It may even provide health benefits. However, some evidence suggests that caffeine consumption may trigger episodes of extreme mood disturbances in people with bipolar disorder.

Bipolar disorder is characterized by dramatic fluctuations in mood. People with the condition may unpredictably oscillate between episodes of mania and depression.

Many clinical trials involving people with bipolar disorder require participants to limit or avoid caffeine. This may be because of caffeine’s potential effects on bipolar disorder symptoms, as well as possible drug interactions.

In this article, we examine the effects of caffeine on people with bipolar disorder. We look at how it affects the symptoms, the efficacy of treatment, and people’s overall well-being.

Studies on the effects of caffeine on bipolar disorder symptoms are limited. Most recommendations are based on case reports.

Experts warn that researchers need to conduct more studies to understand and interpret the possible effects of caffeine on bipolar disorder symptoms.

Manic symptoms

Most research on the effects of caffeine on people with bipolar disorder indicates that the stimulant may trigger manic episodes.

Caffeine acts as a mood elevator. Some experts have suggested that caffeine may, as a result, trigger the disorder’s manic episodes, which some may refer to as high periods.

Case reports have described individuals who experienced manic episodes with psychotic features, such as delusions of grandeur, after consuming large quantities of caffeine.

One report notes that the person had not adhered to their bipolar disorder treatment plan. Stopping or modifying treatment without consulting a psychiatrist raises the risk of mood destabilization and increases susceptibility to the mood-altering effects of caffeine.

Depressive symptoms

Many studies have looked at the effects of caffeine on symptoms of depression among the general population. They generally find that moderate caffeine consumption — meaning up to 400 milliliters per day — may reduce the likelihood of depression. However, caffeine withdrawal can also lead to depression-like symptoms, such as low mood, difficulty concentrating, and irritability.

Researchers have not extensively studied the effects of caffeine on depressive symptoms in people with bipolar disorder.

However, the results of an older 2009 study, which looked at how drinking coffee affected people with bipolar disorder, led to some concerns. The researchers found no link between coffee consumption and the number of depressive or manic episodes a person experienced in a year. However, people with bipolar disorder who regularly drank coffee were more than twice as likely to engage in suicidal acts.

Again, more research is necessary to confirm the effects of caffeine on bipolar disorder symptoms.

Caffeine may also affect bipolar disorder symptoms by interfering with treatment.

The enzyme cytochrome P450 1A2, known as CYP1A2, metabolizes caffeine. It also metabolizes many other types of medications, including antipsychotics that doctors use to treat bipolar disorder. These include clozapine (Clozaril) and olanzapine (Zyprexa).

Caffeine and antipsychotic medications compete for a finite amount of CYP1A2 in the body. Ingesting too much caffeine decreases the amount of CYP1A2 enzyme available for the body to metabolize medications. This can lead to a potentially dangerous buildup of these medications.

A recent report described a person who was taking clozapine and began consuming 600 milligrams (mg) of caffeine — in the form of four energy drinks — daily for 3 weeks. He experienced clozapine toxicity that resulted in lung and kidney failure.

Caffeine may interfere with the metabolization of other types of medications that people with bipolar disorder may take to alleviate their symptoms, including some antidepressants and anti-anxiety medications.

Heavy caffeine consumption can affect the blood levels of lithium, a mood stabilizer that doctors commonly use to treat bipolar disorder. The body excretes lithium in the urine. As caffeine is a diuretic, it may lower the levels of lithium in the body by increasing the urine output.

Other research suggests that stopping caffeine consumption may increase lithium levels and improve treatment effects.

Quality sleep is an important component of managing the symptoms of bipolar disorder. Sleep dysregulation, which can affect mood stability, is common among people with bipolar disorder.

Caffeine intake can decrease sleep quality. Research suggests that caffeine use is higher among people with bipolar disorder and poor sleep quality.

Given the possible unintended consequences of caffeine on overall sleep quality, people with bipolar disorder who need an energy boost may wish to focus on improving their sleep hygiene. Steps for doing this include:

  • putting a consistent nighttime routine in place
  • refraining from using electronic devices before bed
  • increasing daily physical activity
  • avoiding eating large meals shortly before going to bed

The Food and Drug Administration (FDA) recommends that most adults limit their caffeine consumption to no more than 400 mg per day to avoid negative side effects. However, this limit may be different for people who are sensitive to the effects of caffeine, such as people with bipolar disorder.

There is no set rule for how much caffeine is safe for people with bipolar disorder to consume. Most reports suggest that caffeine-induced manic episodes occur after excessive caffeine consumption, meaning more than 600 mg per day. It is unclear whether effects may occur with lower amounts.

The International Bipolar Foundation recommends that people with bipolar disorder avoid caffeine entirely. The British Association for Psychopharmacology, on the other hand, suggests that individuals likely to be sensitive to caffeine simply monitor their intake and reduce it if necessary.

People with bipolar disorder should discuss their caffeine consumption with a psychiatrist to determine whether limitations are advisable for them.

Sources of caffeine

It is important to check the specific caffeine levels before consuming any products. However, the product information available online suggests that typical caffeine levels in some common sources are:

  • Coffee: 95 mg per 8-ounce (oz) cup
  • Decaffeinated coffee: 4 mg per 8-oz cup
  • Espresso: 65 mg per 1.5-oz shot
  • Black tea: 47 mg per 8-oz cup
  • Green tea: 28 mg per 8-oz cup
  • Regular or diet dark soda: 40 mg per 12-oz can
  • Dark chocolate: 24 mg per 1 oz
  • Energy drinks: 170 mg per 16-oz can

Some pain relievers may also include high quantities of caffeine.

Some evidence suggests that caffeine may worsen mood destabilization in bipolar disorder, potentially leading to manic episodes. Caffeine can also disrupt bipolar disorder treatment, resulting in potentially dangerous side effects or reduced treatment effectiveness.

People with bipolar disorder who regularly consume caffeine may wish to consider limiting their intake or cutting it out entirely. A psychiatrist can help decide what amount of caffeine is appropriate for a person based on their current treatment plan and symptoms.