In addition to fosfomycin 3gm sachet primary effects in treating bacterial infections, fosfomycin may cause several side effects. Common side effects include gastrointestinal issues like diarrhea, nausea, and abdominal pain. Some patients may experience headaches, dizziness, or fatigue. Less common, but more serious side effects can include allergic reactions such as rash, itching, swelling, or difficulty breathing. In rare cases, fosfomycin may cause Clostridium difficile-associated diarrhea, a potentially severe condition. As with any antibiotic, there is also a risk of developing antibiotic resistance if the medication is not used properly. It’s important to take fosfomycin exactly as prescribed and to report any unusual or severe side effects to your healthcare provider.