Penicillin interaction with other drugs

Penicillin may alter the results of some medical tests, such as those for the presence of sugar in the urine. Penicillin can also interact with a number of other medications, including blood thinners, thyroid drugs, blood pressure drugs, birth control pills, and other antibiotics, in some cases decreasing their effectiveness. 

Anaphyla. is is a type I reaction in which the drug ( ) interacts with IgE lixed to mast cells contrast media) can produce an anaphylaxis-like (anaphylactoid) reaction on first exposure. 

The increased levels and decreased renal excretion of clinafloxacin caused by probenecid are not considered large enough to warrant dosage adjustment," and most of the changes seen with the other quinolones were of a similar magnitude. However, caution has been advised in the presence of other drugs that may also compete for renal excretion (such as some penicillins or cephalosporins). " Grepafloxacin, moxifloxacin, sparfloxacin, and probably ofloxacin, appear not to interact. 

The interactions between the oral contraceptives and tetracyclines summarised here are all that have been identified in the literature. Much of the evidence is anecdotal with insufficient controls (if any). These interactions are not adequately established and the whole issue remains controversial. Bearing in mind the extremely wide use of both drugs, any increase in the incidence of contraceptive failure above the accepted failure rate is clearly very low indeed. On the other hand, the personal and ethical consequences of an unwanted pregnancy can be very serious. For this reason, the Faculty of Family Planning and Reproductive Health Care (FFPRHC) Clinical Effectiveness Unit recommends that an additional form of contraception, such as condoms, should be used while taking a short course of antibacterials that do not induce liver eiKymes, and for 7 days after the antibacterial has been stopped. See Hormonal contraceptives + Antibacterials Penicillins , p.981, for more detailed information on how to manage this interaction. 

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