There is currently little evidence of adverse effects of prolonged antibiotic therapy on female fertility and the ability of a woman to conceive.
However, several commonly used antibiotics have been shown to negatively affect fertility in males. Antibiotics such as tetracycline, aminoglycosides, nitrofurantoin or macrolides, such as erythromycin, may lower sperm count and impair sperm viability and motility. In males that have been treated with these antibiotics for a longer period of time, sperm counts may be significantly lower or a large percentage of the sperm may be non-viable. If the testicles fail to produce sperm cells completely, the condition is termed non-obstructive azoospermia.