From common cold tablets to antidepressants<\/a>, caffeine<\/a>\u2019s impact on the body goes far beyond a quick energy boost. Tea also contains caffeine<\/a> but not in the same concentrations as coffee<\/a>, and doesn\u2019t seem to affect people in the same way. <\/p>\n Here\u2019s what you should know about how coffee can interfere with your medications \u2013 and how to stay safe.<\/p>\n 1. Cold and flu medicines<\/p>\n Caffeine is a stimulant, which means it speeds up the central nervous system. Pseudoephedrine, a decongestant found in cold and flu remedies such as Sudafed, is also a stimulant. When taken together, the effects can be amplified \u2013 potentially leading to jitters or restlessness, headaches, a fast heart rate and insomnia.<\/p>\n Many cold medications already contain added caffeine, increasing these risks further. Some studies also suggest that combining caffeine with pseudoephedrine can raise blood sugar and body temperature, particularly important for people with diabetes.<\/p>\n Stimulant effects are also a concern when combining caffeine with ADHD medications such as amphetamines, or with asthma drugs such as theophylline, which shares a similar chemical structure to caffeine. Using them together may increase the risk of side effects such as a rapid heartbeat and sleep disruption.<\/p>\n 2. Thyroid medication<\/p>\n Levothyroxine, the standard treatment for an underactive thyroid, is highly sensitive to timing \u2013 and your morning coffee can get in the way. Studies show that drinking coffee too soon after taking levothyroxine can reduce its absorption by up to 50 per cent.<\/p>\n Caffeine speeds up gut motility (the movement of food and waste through the digestive tract), giving the drug less time to be absorbed \u2013 and may also bind to it in the stomach, making it harder for the body to take in. These effects reduce the drug\u2019s bioavailability, meaning less of it reaches your bloodstream where it\u2019s needed. This interaction is more common with tablet forms of levothyroxine, and less likely with liquid formulations.<\/p>\n open image in gallery<\/p>\n Caffeine speeds up gut motility, giving the drug less time to be absorbed (Getty Images)<\/p>\n If absorption is impaired, symptoms of hypothyroidism \u2013 including fatigue, weight gain and constipation \u2013 can return, even if you\u2019re taking your medicine<\/a> correctly.<\/p>\n The same timing rule applies to a class of osteoporosis medications called bisphosphonates, including alendronate and risedronate, which also require an empty stomach and around 30-60 minutes before food or drink is taken.<\/p>\n 3. Antidepressants and antipsychotics<\/p>\n The interaction between caffeine and mental health medications can be more complex.<\/p>\n Selective serotonin reuptake inhibitors (SSRIs), such as sertraline and citalopram, are a type of antidepressant medication widely used to treat depression, anxiety and other psychiatric conditions. Lab studies suggest caffeine can bind to these drugs in the stomach, reducing absorption and potentially making them less effective.<\/p>\n Tricyclic antidepressants<\/a> (TCAs), such as amitriptyline and imipramine, are a class of older antidepressants that work by affecting the levels of neurotransmitters in the brain. They were among the first antidepressants developed and are less commonly used today, compared with newer antidepressants such as SSRIs, due to their potential for more side effects and higher risk of overdose.<\/p>\n About the author<\/p>\n Dipa Kamdar is a Senior Lecturer in Pharmacy Practice at Kingston University.<\/p>\n This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n TCAs are broken down by the liver enzyme CYP1A2, which also metabolises caffeine. The competition between the two can slow drug breakdown, increasing side-effects, or delay caffeine clearance, making you feel jittery or wired longer than usual.<\/p>\n Clozapine, an antipsychotic, is also processed by CYP1A2. One study showed that drinking two-to-three cups of coffee could increase blood levels of clozapine by up to 97%, potentially increasing risks such as drowsiness, confusion, or more serious complications.<\/p>\n 4. Painkillers<\/p>\n Some over-the-counter painkillers<\/a>, such as those containing aspirin<\/a> or paracetamol<\/a>, include added caffeine. Coffee can speed up how quickly these drugs are absorbed by accelerating how fast the stomach empties and making the stomach more acidic, which improves absorption for some medications, such as aspirin<\/a>.<\/p>\n![\"Caffeine](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/07\/iStock-1859646927.jpg\")
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