Anti-infective agents include antibiotics, antibacterials, antifungals, antivirals and antiprotozoals. Specific medications used to treat infections include antibiotics, antivirals, antifungals, antiprotozoals, and antihelminthics. Antiviral resistance can emerge during or after treatment with antivirals in certain people (e.g., immunosuppressed). Medications used for treatment include antivirals, cytotoxic chemotherapy and rituximab. Like antibiotics, specific antivirals are used for specific viruses. Depending on the causal agents, antivirals or antifungals can be added. Evidence for antibiotics, antivirals, bronchodilators, or nebulized epinephrine is either unclear or not supportive. Treatment is usually with antivirals such as acyclovir or valacyclovir by mouth. In 2014, Japan approved favipiravir for treating influenza strains unresponsive to current antivirals. Administering gabapentin along with antivirals may offer relief of postherpetic neuralgia. There is limited evidence for the use of antivirals in acute hepatitis C infection. A number of topical antivirals are effective for herpes labialis, including aciclovir, penciclovir, and docosanol. Resistance to HIV antivirals is problematic, and even multi-drug resistant strains have evolved. Antivirals and human immunoglobulin-sourced treatments are usually for relief of symptoms. Researchers are working to extend the range of antivirals to other families of pathogens.