Side effects of antihistamines on the liver
In rare cases, side effects of antihistamine therapy also manifest themselves in the liver. Numerous antihistamines are metabolised in the liver. Both activation of the preparation and excretion via the liver are possible.
In this process, the liver is put under great strain, which can lead to increasing damage to the liver if the drug is taken over a long period of time. For this reason, attention should be paid to possible interactions, especially when antihistamines are combined with other drugs that are metabolised via the liver. The simultaneous consumption of alcohol can also increase the effect and cause additional damage to the liver.
Most first-generation antihistamines are available over the counter in pharmacies. Often the preparations are also offered in combination with other drugs for anti-allergic therapy. However, especially in (small) children, there are sometimes considerable side effects.
As these antihistamines also accumulate in the central nervous system, this can lead to increased daytime tiredness and mild dizziness. Concentration disorders are also frequently reported. In addition, hallucinations and seizures are possible in children if the dosage is very high or overdosed.
Typically, the remaining side effects of antihistamines also occur, especially in small children. Initially, this leads to increased dryness of the mouth, problems with urination and constipation. In individual cases, cardiac rhythm disturbances are also possible, as individual preparations lead to an extension of the QT time in the ECG.
In newborns and infants there is also the risk of respiratory disorders. As a consequence, there is a risk of cardiovascular collapse. A rather rare side effect of treatment with antihistamines is weight change.
However, the effects of the individual antihistamines on weight vary greatly. While some preparations have no effect whatsoever on appetite and weight, other preparations can cause weight gain of several kilograms within a few weeks. However, these occur mainly during long-term therapy and develop slowly and continuously over a longer period of time.
The weight gain is due to a blockage of the histamine receptors, which causes a slight increase in appetite, resulting in weight gain. Numerous antihistamines are metabolised by the liver. Both activation and excretion of the preparations take place via specific enzymes of the liver.
The liver is put under a lot of strain in the process. When antihistamines are combined with alcohol, the effect can be mutually reinforcing. In addition, the function of the liver is stressed even more, which can lead to damage to the liver.
For this reason, the consumption of alcohol during treatment with antihistamines should be avoided if possible. Especially the first and second generation antihistamines lead to considerable side effects when combined with alcohol. Common symptoms of a combination of antihistamines with alcohol are increased fatigue with reduced alertness and light drowsiness.
In addition, massive impairment of concentration is to be feared. In individual cases, life-threatening cardiovascular disorders may also occur. So far, no harmful effects on mother and child have been proven for the majority of the common antihistamines.
Some preparations are even used specifically during pregnancy. These include doxylamine, for example, which is used in the treatment of pregnancy vomiting. When long-term medication with older antihistamines (diphenhydramine, hydroxyzine, dimenhydrinate) is taken during pregnancy, few studies have shown mild withdrawal symptoms in the newborn (including increased tremor and diarrhea).
In addition, effects on the contraction of the uterine muscles have also been demonstrated. For this reason, these substances in particular should be avoided during pregnancy. All medication during pregnancy should always be taken in consultation with the doctor treating the patient.
In a few cases, the combination with another preparation may also pose a serious risk to the child. With the first generation of antihistamines, it was discovered relatively early on that increased fatigue occurs during antiallergic therapy. The preparations inhibit the wake-up reaction in the central nervous system.
For this reason, these substances were further modified so that they can also be used exclusively as sleeping pills. Frequently used active ingredients are doxylamine and diphenhydramine. They belong to the group of non-prescription sleeping pills and can especially support mild and non-chronic sleep disorders.
However, in order to avoid daytime tiredness, care should be taken to take them before going to bed. The substances are generally well tolerated. Nevertheless, many side effects can occur if the preparations are taken regularly.
These include dizziness, concentration problems and headaches. Dry mouth, constipation and problems urinating are also possible.
