Lithium is a medication commonly prescribed as a mood stabilizer, primarily used in the management of bipolar disorder. Ibuprofen is a widely used over-the-counter nonsteroidal anti-inflammatory drug (NSAID) taken for pain relief, fever reduction, and inflammation. Combining these two medications carries a significant risk of a dangerous drug interaction. Patients taking lithium are strongly advised to avoid Ibuprofen due to the potential for drastically increased lithium levels in the bloodstream.
How Ibuprofen Affects Lithium Levels
The interaction between Ibuprofen and lithium occurs because the NSAID directly interferes with the body’s mechanism for clearing lithium, which happens almost entirely through the kidneys. Lithium has a narrow therapeutic window, meaning the difference between an effective dose and a toxic dose is quite small. It is constantly filtered and excreted by the renal system to maintain a steady, safe concentration in the blood.
Ibuprofen and other NSAIDs work by inhibiting certain enzymes, which reduces the production of compounds called prostaglandins in the kidneys. These prostaglandins normally help regulate blood flow within the kidney and promote the excretion of sodium and lithium. When Ibuprofen reduces prostaglandin activity, it causes a reduction in blood flow to the kidneys, which lowers the rate at which waste products are filtered from the blood.
The reduced filtration rate causes the kidneys to retain more lithium than they would otherwise. This retention leads to a buildup of the drug in the body, causing serum lithium concentrations to rise. NSAIDs can increase lithium levels by a range of 12% to 66% in some individuals, sometimes within just a few days. This increase can rapidly push the concentration past the safe therapeutic range and into toxicity.
Recognizing Symptoms of Lithium Toxicity
When lithium levels climb above the safe range, it can cause lithium toxicity, which can be life-threatening. The symptoms often appear on a spectrum, starting with milder signs. Early or mild symptoms usually involve the digestive system and include nausea, vomiting, diarrhea, and abdominal cramping.
As the lithium concentration continues to rise, the symptoms progress to affect the nervous system and become more severe. Moderate toxicity can manifest as confusion, lethargy, drowsiness, and pronounced muscle weakness. Patients may experience an uncontrolled fine tremor, poor coordination leading to trouble walking (ataxia), and slurred speech.
In the most severe cases of toxicity, the effects can include seizures, delirium, and a complete loss of consciousness, potentially leading to coma. Severe toxicity can also cause permanent neurological damage or serious kidney injury. Any appearance of these symptoms, even the mild gastrointestinal distress, should prompt the individual to seek immediate medical attention and have their blood lithium level checked.
Safer Alternatives for Pain and Fever
Because of the significant interaction risk, individuals taking lithium should avoid all NSAIDs, including Ibuprofen and Naproxen (Aleve). The safest alternative for managing pain and fever is Acetaminophen, known by the brand name Tylenol. Acetaminophen does not interfere with the renal clearance of lithium, making it a safe option when taken at the recommended dose.
Acetaminophen provides effective relief for mild to moderate pain and reduces fever without impacting the kidney’s ability to excrete lithium. It is important to adhere strictly to the recommended dosing guidelines and not exceed the maximum daily limit to avoid potential liver toxicity. Before taking any new medication, even an over-the-counter product like Acetaminophen, it is advisable to consult with a prescribing physician or pharmacist. This ensures the choice is appropriate for the individual’s specific health situation.