Many medications can thin the blood or interact with the heart. For this reason, people who have atrial fibrillation (AFib) should speak with a medical professional before using certain drugs, such as pain relievers.

AFib is among the most common arrhythmias (heart rhythm issues). It causes an irregular and sometimes rapid heartbeat. It may occur when the heart’s lower chambers do not pump hard enough or fill completely. AFib can be ongoing or occur in shorter episodes of a fluttering or pounding heartbeat.

Without treatment, AFib increases a person’s risk of life threatening cardiovascular complications such as heart failure or stroke. Some people will need to take medications, adjust their lifestyle, or undergo medical procedures to manage the condition. However, certain other drugs can make AFib worse or increase a person’s risk of complications.

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People often take non-steroidal anti-inflammatory drugs (NSAIDs) as over-the-counter (OTC) pain and inflammation relief.

However, according to a 2023 study using data from 18,201 people, taking NSAIDs while on a course of a blood-thinning medication called apixaban links to an increased risk of major and nonmajor bleeding. An earlier review links NSAIDs to an increased risk of bleeding even without taking blood-thinning medications.

Health experts indicate that NSAIDs may also increase a person’s risk of heart attack or stroke. Individuals with AFib already have a stroke risk five times higher than people who do not have AFib, according to the United Kingdom’s National Health Service (NHS).

The Food and Drug Association (FDA) notes that taking aspirin every day may help prevent heart attacks and clot-linked strokes in some people. This is because aspirin alters how the blood clots. However, this can also increase the risk of bleeding in people who already take blood-thinning medications, such as:

A 2023 study tracked around 19,000 healthy older adults taking either 100 milligrams of aspirin or a placebo daily for 5 years. The findings show that daily aspirin use did not reduce stroke risk more than a placebo and may increase the risk of brain bleeds.

People considering taking aspirin to manage headaches or other aches and pains should speak with a medical professional.

According to a 2023 review, some antibiotics can interfere with the function of a particular enzyme called P450-2C9, also known as CYP2C9. This enzyme is crucial to how the body absorbs and uses warfarin, meaning that antibiotics may reduce the effectiveness of some AFib medications.

Antibiotics that inhibit this enzyme include:

  • anti-mycobacterial agents
  • fluoroquinolones
  • sulfa drugs
  • metronidazole

In addition, some antibiotics can reduce the population of gut bacteria that produce vitamin K, which may alter how the body responds to warfarin, as vitamin K has close links to blood clotting.

People with hypothyroidism (low levels of thyroxine, a hormone the thyroid gland produces) may need to take a lab-made version of thyroxine called levothyroxine. While taking levothyroxine can help reduce symptoms of hypothyroidism, people with heart problems such as AFib are not suitable candidates for this medication.

Hyperthyroidism (excessive thyroid hormone levels) has strong links to AFib. For example, a large 2017 systematic review connects high levels of thyroxine to a higher risk of AFib.

Sometimes, an excessive dose of levothyroxine may link to a significant increase in AFib risk by overcorrecting levels in people with hypothyroidism. In a 2021 study, high and medium levothyroxine doses linked to an increased AFib risk in 30,560 people who had an episode of AFib compared with those who received a lower dose.

However, an older study in Taiwan involving 12,283 people with AFib who took levothyroxine found no link to an increased risk of heart attack, stroke, or heart failure.

Some people take stimulant medications, such as methylphenidate, to manage attention-deficit hyperactivity disorder (ADHD).

A 2018 study involving 2,013 children found that those taking stimulant medication had a higher heart rate and blood pressure than those who did not.

A 2022 review concluded that people with ADHD and cardiovascular disease can use stimulant medications safely. However, it is important for a medical professional to carefully prescribe their dosage, as stimulants may trigger or worsen AFib and other conditions that affect heart rhythm.

Antidepressants are vital in managing depression for some people.

A 2022 meta-analysis using data from over 2.6 million participants found that antidepressants have a significant link to an increased risk of AFib. The research suggests a particular link to a higher risk with selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants.

According to the review, females with AFib who took antidepressants had an especially high risk.

According to the American Heart Association, taking decongestants, such as phenylephrine or pseudoephedrine, for a blocked nose constricts blood vessels. This may create problems for people with underlying heart disease by speeding up the heart and increasing blood pressure.

Pseudoephedrine is also a stimulant. As this article states above, these medications interact with the heart and may increase blood pressure.

For people who experience episodes of AFib, certain stimuli and situations can trigger one, including:

  • drinking excessive amounts of alcohol in a single sitting
  • having excess body weight
  • consuming large volumes of caffeine
  • taking illicit substances such as cocaine or amphetamines
  • smoking tobacco

Reducing exposure to these triggers can reduce a person’s risk of AFib episodes.

Different types of medications may interact with AFib and its treatments. For example, NSAIDs and aspirin may thin the blood on top of prescribed blood thinners’ actions. Some antibiotics interfere with how the body uses warfarin. Thyroid hormone supplements can increase thyroxine levels too far, increasing a person’s AFib risk.

Some medications, such as those used to treat allergy symptoms, congestion, and ADHD, contain stimulants. These can increase blood pressure and heart rate, which can lead to a higher risk of complications for a person with AFib.

A person can discuss medication options with a doctor to learn about alternatives or safety measures for each drug.