What anesthetic alternatives are there for nitrous oxide?

None. Nitrous oxide is a vapor with rapid onset and offset, poor anesthesia (amnesia) maintenance, and excellent analgesia in high concentrations. As such, it is unique in its properties. There are intravenous equivalents, but none that can be simply breathed. It's major side-effect is nausea and vomiting, so it's popularity as an anesthesia adjunct in diminishing.
Prostanoids. There are a number of agents with similar physiologic effects and less as inhaled nitric oxide. The most researched once are inhaled prostanoids: prostacyclin and iloprost.
Nitrous. Nitrous oxide has been a wonderful help to patients that have anxiety during dental procedures and up until now sedation has been the only alternative, however there is a new relaxation method that some dentists have been using called NuCalm.

Related Questions

Please tell me what anesthetic alternatives exist to nitrous oxide?

There are many. Options - local anesthetic, anxiolysis, nitrous sedation, IV sedation, general anesthesia. Hope this helps. Read more...
Plenty. Nitrous oxide is not a complete anesthetic. Any other inhaled agent can be substituted, and there are many intravenous agents that can also serve the purpose. In general, nitrous oxide is considered to be relatively innocuous. Read more...

What anesthetic alternatives exist for nitrous oxide if a person was allergic to it?

Many. Allergic reactions to nitrous oxide are extremely rare. However, if a true allergy exists, there are many alternatives depending on the indication for anesthesia. Sedation can be achieved with intravenous agents and if general anesthesia is required, volatile anesthetics can be used. Read more...