Indicated to combat acute pain and fever, metamizol is one of the most consumed active ingredients in Spain. It has several trade names, but we often find it in its generic form, either in 575 mg capsules, ampoules or injections.
It is a drug that, unlike anti-inflammatories such as ibuprofenhas a good digestive tolerance and is very safe, but, like all drugs, it is not exempt from side effects, some of them serious, so it must be taken with caution, not more than a week in a row and under the prescription of a doctor.
Adverse effects of metamizole
As warned by the CIMA (Spanish Agency for Medicines and Health Products) in the data sheet of this active ingredient, metamizol can have various side effects, from the mildest, such as a slight drop in blood pressure -something that happens to one out of every ten patients-, rashes how many in one out of every 100, allergic reactions in one in 1,000 or other very rare, such as agranulocytosis or serious kidney and liver problems. In general, we can divide adverse effects into five groups:
Hematological. Metamizol can cause leukopenia, which is a decrease in the number of white blood cells in the blood. If this decrease is very severe, it is known as agranulocytosis, a very rare but very serious side effect, as it can compromise the patient’s life. This reaction does not depend on the dose and can appear at any time, and even in patients who have previously received metamizole with no problems. Metamizole can also reduce the number of red blood cells and platelets.
Allergic reactions. Metamizole can cause allergic reactions of lesser or greater severity, from skin rashes, hives or rhinosinusitis to asthma or anaphylactic shock, which is very rare. For this reason, it is recommended that people with asthma or atopy take it with caution and in the case of patients at high risk of anaphylactoid reactions, assess whether treatment is appropriate.
in blood pressure. In one in 10 patients, blood pressure may drop, especially in patients with pre-existing arterial hypotension, hypovolemia, dehydration, circulatory instability, incipient circulatory failure or with very high fever. In these cases, hypotension can become severe.
Skin reactions. Although very rare, metamizole can cause serious skin reactions, such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS), which can be life-threatening or serious. The first warning sign is the appearance of vesicles or blisters, erythema, ulcers in the mouth or
Liver. In some cases, cases of hepatitis have been reported, manifesting with symptoms such as jaundice, skin rashes, fever, increased blood level of liver enzymes… Most patients recover after discontinuation of treatment, but in isolated cases it progressed to acute liver failure.
Kidneys. In rare cases, metamizole can cause kidney damage, manifested as inflammation of the kidney (interstitial nephritis), decreased or suppressed urine output, increased amount of protein excreted in the urine, or chromaturia (abnormal coloration of the urine). urine).
Other very rare side effects they can be gastrointestinal bleeding, Kounis syndrome (a type of heart disorder), or sepsis (a serious infection involving an inflammatory reaction of the whole body).
When to see a doctor
As the Spanish Agency for Medicines and Health Products warns, if we are taking metamizol and notice any of these symptoms, we must go to a medical center as soon as possible:
•Feeling sick: nausea, vomiting, fever, feeling tired, loss of appetite…
•Very dark urine.
•Symptoms of liver damage, such as light colored stools, yellowing of the skin or the whites of the eyes, itching, rash or pain in the upper stomach area.
•Signs of allergic reactions, such as skin and mucosal reactions (itching, burning, redness, swelling, hives…), difficulty breathing, swelling of feet, hands, lips, throat or airways…
•Hematological or cardiac signs: heart rhythm disturbances and decreased blood pressure, very pale skin, fatigue…
In addition, it is recommended that people who have previously had allergic reactions or hematological reactions with drugs containing metamizole or other similar compounds, have suffered from symptoms of asthma, rhinitis or urticaria, suffer from acute porphyria, genetic deficiency of glucose-6-, do not take metamizol. phosphate dehydrogenase, has undergone alterations in bone marrow function and during pregnancy and lactation.