Introduction – How can medication influence the effectiveness of the pill?
Interactions with other medications can weaken the contraceptive effect of the pill. Conversely, hormonal contraceptives (the Pill) can also alter, increase or weaken the effectiveness of drugs. Before taking a medicine, the prescribing doctor should be informed about the use of the pill.
Whether the effectiveness of the pill may be reduced can also be read in the package insert of the medication. If you are uncertain, a doctor or pharmacist should always be consulted. If the effectiveness of the pill is affected by taking other medicines, it is essential to use additional contraceptives, as the contraceptive effect is no longer guaranteed. This can lead to unwanted pregnancies. A first sign of the pill’s reduced effectiveness can be the occurrence of intermittent bleeding.
Drugs with influence
- ASS or acetylsalicylic acid: These painkillers, also known as aspirin, are used as anticoagulants. ASA can basically interact with other drugs, which is why it should not be taken without indication and at best in consultation with a doctor or pharmacist. ASA can alter the lining of the stomach and thus possibly influence the absorption of the pill.
There are no clear indications of the pill’s reduced effectiveness, but spontaneous reports of unwanted pregnancies when taking acetylsalicylic acid have been reported.
- Etoricoxib (Arcoxia®): Like ASA, coxibe belongs to the non-steroidal anti-inflammatory painkillers. They are associated with a lower risk of bleeding in the gastrointestinal tract and are offered as an alternative. Coxibs, especially in long-term therapy, can also interact with hormonal contraceptives and other drugs.
An interaction with the pill cannot be ruled out with certainty.
In principle, all antibiotics can influence the effectiveness of the pill, especially through changes in the gastrointestinal tract. Diarrhoea, for example, which is a common side effect of antibiotics, can shorten the time the drug remains in the digestive system and affect its absorption. There are similar reports for the broad-spectrum antibiotics chloramphenicol and neomycin, and the combination cotrimoxazole.
On the other hand, there is no evidence of reduced efficacy for the fluoroquinolones ciprofloxacin and ofloxacin. Doxycycline and metronidazole also show no significant interaction with the pill. As a matter of principle, the doctor treating you should be consulted in detail when taking an antibiotic.
Signs of reduced effectiveness may be the occurrence of inter-bleeding during otherwise regular cycles. In case of doubt, additional contraceptive measures should be used for the duration of the treatment and the following month to provide full protection against unwanted pregnancy. Here you will find an overview of the topic: Antibiotics
- There is clear evidence of reduced effectiveness of the pill for the antibiotic rifampicin, which is used in the treatment of tuberculosis.
Like some other antibiotics, it affects the metabolism of the pill and the protection against unwanted pregnancy is impaired.
- Corresponding indications can also be found in the group of macrolides (Clarithromycin, Erythromycin, Azithromycin and others).
- There are also spontaneous reports of unwanted pregnancies for various active ingredients from the penicillin group (penicillin G, amoxicillin, ampicillin, oxacillin) and the tetracycline and cephalosporin group.
There is a variety of drugs that are used as sleeping pills (so-called hypnotics). Some of them can influence and weaken the effect of the pill. Patients who are prescribed sleeping pills should inform their doctor about taking hormonal contraceptives and, if necessary, take additional contraceptive measures.
Sleeping pills include the following groups: Here you will find an overview of the topic: Sleeping pills
- Antihistamines: These include diphenhydramine, for example. Antihistamines are used in the therapy of nausea and vomiting and also have anti-allergic effects. They also have a sedative effect.Diphenhydramine does not seem to have any influence on the effectiveness of the pill.
- Benzodiazepines: Benzodiazepines are used as sedatives and sleeping pills.
The members of this group include lorazepam, flurazepam, midazolam (known as Dormicum), diazepam (Valium) and others. Benzodiazepines are potent drugs and interact with many other drugs. The effectiveness of the pill may be reduced.
The pill may also influence the effects of benzodiazepines and increase the risk of side effects.
- Promethazine: This is a neuroleptic and is used today mainly as a sleeping aid and sedative. Taking oral contraceptives can inhibit the breakdown of phenotiazines and increase their effects. This increases the risk of side effects of the drugs.
At the same time the drugs can influence the effectiveness of the pill, so that adequate protection against unwanted pregnancy cannot be guaranteed.
Antiepileptic drugs are drugs used to treat seizures in the context of epilepsy disorders. In principle, all antiepileptic drugs can interact with the Pill, especially older drugs interfere with the liver metabolism and the breakdown of drugs. Both a faster and a slower breakdown of the pill leads to a weakening of the contraceptive effect.
Clear evidence of this was found in the following antiepileptic drugs: carbamazepine, felbamate, oxcarbazepine, phenytoin, phenobarbital, primidone and topiramate (in the dosage over 200mg per day). This also includes “newer” antiepileptic drugs. However, there are also a number of drugs that apparently do not reduce the effect of hormonal contraceptives.
Nevertheless, an interaction cannot be ruled out. This also applies to the effectiveness of the respective antiepileptic, which may also be altered. This is particularly true of lamotrigine: although the effect of the pill does not appear to be diminished, there is an increased excretion of lamotrigine when taken at the same time and thus a diminishing effectiveness of the antiepileptic.
Seizures can be the result of too low a level of lamotrigine. Medications that do not appear to decrease the effectiveness of the pill are ethosuximide, gabapentin, levetiracetam, pregabalin (in doses of less than 200mg per day), valproic acid, vigabatrin and zonisamide. Patients who are permanently treated with an anti-epileptic drug should talk to their doctor about contraception.
This applies to patients with epilepsy, but also to patients taking antiepileptic drugs based on other diagnoses, such as bipolar disorder or neuropathic pain.
- St. John’s wort is a herbal medicine.
It is used for mild to moderate depression and is said to have mood-lifting and anxiety-relieving effects. St. John’s wort can accelerate the metabolism of other drugs and weaken their effect, including the pill. When taking St. John’s wort, additional contraception should be used, as the contraceptive effect of the pill cannot be further guaranteed.
- Grapefruit juice also interacts with the contraceptive pill.
By influencing the metabolism of the pill, the effect of the pill is altered and the risk of side effects is increased. In addition to the pill, grapefruit has interactions with many other drugs, so consumption should be carefully considered. In order to maintain optimum contraceptive protection, large quantities of grapefruit juice should be avoided.
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