caffeine
29 interactions related to caffeine
caffeine + ashwagandha
Ashwagandha is an adaptogen that lowers cortisol and reduces perceived anxiety; caffeine is a stimulant that raises cortisol and can increase anxiety. Taking them together can blunt caffeine's anxiety and jitter side effects while preserving its alertness benefit, but ashwagandha may also slightly dampen caffeine's peak stimulant effect.
l-theanine + caffeine
L-theanine, an amino acid from tea, smooths out caffeine's stimulant effects by promoting alpha-wave brain activity associated with relaxed alertness, while caffeine blocks adenosine receptors to increase arousal — the combination has been shown in multiple human trials to improve sustained attention and reaction time more than either alone.
lithium + caffeine
Caffeine increases renal clearance of lithium by promoting natriuresis and increasing glomerular filtration, so chronic caffeine intake lowers lithium blood levels. A sudden reduction in caffeine intake can raise serum lithium into the toxic range, while abruptly increasing caffeine can lower levels and worsen mood symptoms.
caffeine + propranolol
Caffeine raises systemic vascular resistance and heart rate, partially opposing propranolol's blood-pressure and heart-rate lowering effects. High caffeine intake can also worsen tremor and anxiety that propranolol is prescribed to treat.
caffeine + ciprofloxacin
Ciprofloxacin is a potent CYP1A2 inhibitor. Co-administration increases caffeine's area-under-the-curve by 50-100% and prolongs its half-life, producing exaggerated central nervous system and cardiovascular stimulation.
caffeine + theophylline
Caffeine and theophylline are closely related methylxanthines that share the CYP1A2 metabolic pathway and compete for the same adenosine receptors. Concurrent use can raise theophylline levels and add pharmacodynamically to cause tachycardia, tremor, nausea, seizures or arrhythmias.
caffeine + sertraline
Sertraline and caffeine can each contribute to anxiety, insomnia, tremor and GI upset, and sertraline may modestly slow caffeine clearance via CYP1A2 inhibition. The pharmacokinetic effect is small but the additive symptomatic effect can be uncomfortable.
caffeine + tyrosine
L-tyrosine is a precursor to dopamine and norepinephrine, and caffeine triggers their release; combining them can modestly improve cognitive performance under stress, fatigue, or sleep deprivation. The synergy is generally well tolerated, though it can mildly amplify caffeine's stimulant effects.
smoking + caffeine
Polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2, the enzyme that performs about 95% of caffeine demethylation, raising caffeine clearance by 40-65% and shortening its half-life from roughly 6 hours to 3.5 hours in smokers. Quitting smoking can cause caffeine levels to rise sharply, contributing to jitters, anxiety, palpitations, and insomnia.
energy drinks + beta-blockers
Energy drinks raise sympathetic tone through caffeine, taurine, and guarana, opposing the heart-rate and blood-pressure lowering effects of beta-blockers like metoprolol, atenolol, propranolol, and bisoprolol. Case reports document refractory arrhythmias and hypertensive episodes in patients on beta-blocker therapy who consumed energy drinks regularly.
energy drinks + adderall
Energy drinks deliver high-dose caffeine (often 80-300 mg per can) plus taurine, guarana, and B vitamins that produce additive sympathomimetic effects on top of the amphetamine salts in Adderall. Both substances raise heart rate, blood pressure, and norepinephrine release, which can precipitate palpitations, hypertension, anxiety, insomnia, and in rare cases tachyarrhythmia or coronary vasospasm.
levothyroxine + coffee
Coffee, including espresso and instant coffee, can reduce levothyroxine absorption by roughly 25 to 55 percent when consumed at the same time as the tablet. Chlorogenic acids and tannins in coffee appear to bind levothyroxine and the acidic environment may also alter dissolution and gastric emptying.
coffee + sertraline
Sertraline modestly inhibits CYP1A2-mediated caffeine metabolism, raising caffeine plasma levels and prolonging its half-life. Caffeine can also worsen the anxiety, insomnia, jitteriness, and palpitations that sertraline is often prescribed to treat, blunting the clinical response.
chocolate + adenosine
Caffeine and theobromine from chocolate are competitive antagonists at A1 and A2A adenosine receptors. When intravenous adenosine is used for cardiac stress testing or to terminate supraventricular tachycardia, recent methylxanthine intake can blunt its effects and lead to a falsely negative test or failure to convert the arrhythmia.
chocolate + lithium
The caffeine in chocolate increases renal lithium clearance through its diuretic effect, lowering serum lithium levels. A sudden change in chocolate or caffeine intake — especially abrupt cessation — can cause serum lithium to rise into the toxic range, while sudden additions can push levels sub-therapeutic.
ginseng + caffeine
Panax ginseng has its own mild stimulant and sympathomimetic activity that adds to caffeine's effects on heart rate, blood pressure, and CNS arousal. The combination can produce jitteriness, insomnia, palpitations, anxiety, and elevated blood pressure, with greater risk in people with hypertension, arrhythmia, or anxiety disorders.
caffeine + adderall
Caffeine and amphetamine salts are both sympathomimetic stimulants. Combining them raises heart rate and blood pressure, worsens anxiety and insomnia, and increases the risk of palpitations, arrhythmias and panic attacks.
caffeine + yohimbine
Caffeine and yohimbine are both potent stimulants. Yohimbine blocks alpha-2 adrenergic receptors, raising norepinephrine, while caffeine blocks adenosine receptors and amplifies sympathetic output. Combined, they can cause large rises in heart rate and blood pressure, severe anxiety, tremor, panic attacks, arrhythmias, and have been linked to hospital visits and rare cardiovascular events.
caffeine + creatine
Early studies suggested caffeine blunts the ergogenic effect of creatine on muscle phosphocreatine resynthesis and high-intensity performance, but subsequent randomized trials show the combination is generally additive or neutral; the original blunting effect appears specific to chronic co-ingestion during creatine loading rather than acute pre-workout use.
energy drinks + stimulants
Energy drinks layer high-dose caffeine, taurine, guarana, and ginseng on top of any prescription or recreational stimulant (amphetamine, methylphenidate, modafinil, pseudoephedrine, cocaine), producing additive sympathomimetic effects on heart rate, blood pressure, and CNS arousal. The combined load increases the risk of tachyarrhythmia, hypertensive crisis, severe insomnia, and anxiety.
caffeine + clozapine
Caffeine inhibits CYP1A2, the main enzyme that metabolizes clozapine. High caffeine intake (especially energy drinks) can dramatically raise clozapine levels, with case reports of life-threatening toxicity including multiorgan failure.
coffee + propranolol
Caffeine in coffee acutely raises heart rate and blood pressure, which can counteract the heart-rate and blood-pressure-lowering effects of propranolol, a non-selective beta-blocker. Propranolol may also slow caffeine clearance modestly, increasing caffeine exposure.
guarana + caffeine medications
Guarana seeds contain roughly 2-4 times the caffeine concentration of coffee beans, and the caffeine in guarana adds directly to any caffeine-containing medication (e.g., Excedrin, Fioricet, Cafergot, Anacin, Esgic, NoDoz, Vivarin). The combined caffeine load can exceed safe single-dose thresholds, producing tachycardia, hypertension, jitteriness, GI upset, and insomnia.
caffeine + oral contraceptives
Ethinyl estradiol in oral contraceptives inhibits CYP1A2, the enzyme that metabolizes caffeine. This roughly doubles caffeine's area-under-the-curve and prolongs its half-life, intensifying jitteriness, insomnia and palpitations.
caffeine + vitamin d
In vitro and observational studies suggest high caffeine intake (>300 mg/day) may decrease vitamin D receptor (VDR) protein expression in osteoblasts and is associated with lower serum 25-hydroxyvitamin D levels in some NHANES data. The clinical effect is modest and most relevant for bone health in postmenopausal women with low calcium intake.
energy drinks + lithium
The caffeine in energy drinks increases renal clearance of lithium by raising glomerular filtration rate and sodium excretion, which can lower serum lithium below the therapeutic window and trigger relapse of bipolar symptoms. Conversely, abrupt reduction or cessation of high caffeine intake while on a stable lithium dose can push serum lithium into the toxic range; a published case report documented a 24% rise in serum lithium after caffeine withdrawal.
coffee + ciprofloxacin
Ciprofloxacin is a potent inhibitor of CYP1A2, the enzyme that metabolizes caffeine. Co-administration can reduce caffeine clearance by 30% to 50% and prolong its half-life, leading to higher plasma caffeine levels, jitteriness, insomnia, palpitations, tremor, and (rarely) seizures.
coffee + antidepressants
Many antidepressants (especially fluvoxamine, fluoxetine, sertraline, duloxetine) inhibit CYP1A2 to varying degrees and slow caffeine clearance, while caffeine itself can worsen the anxiety, insomnia, tremor, and tachycardia that antidepressants are often prescribed to treat. MAOIs add a risk of caffeine-induced hypertensive episodes.
hot chocolate + sleep medications
Hot chocolate contains caffeine and theobromine, methylxanthines that antagonize adenosine receptors. Because zolpidem, eszopiclone, benzodiazepines, and other sedatives work in part by amplifying inhibitory neurotransmission, evening hot chocolate can partially blunt their sedative effect and worsen sleep onset and maintenance.