alcohol. Although the regulations are quite specific, it is a  good idea to be more conservative than the regulations. Pilot performance can be seriously degraded by both  prescription and over-the-counter medications, as well as  by the medical conditions for which they are taken. Many  medications, such as tranquilizers, sedatives, strong pain  relievers, and cough suppressants have primary effects that  may impair judgment, memory, alertness, coordination,  vision, and the ability to make calculations. Others, such  as antihistamines, blood pressure drugs, muscle relaxants,  and agents to control diarrhea and motion sickness have  side effects that may impair the same critical functions.  Any medication that depresses the nervous system, such as  sedatives, tranquilizers, or antihistamines can make a pilot  more susceptible to hypoxia. Painkillers can be grouped into two broad categories:  analgesics and anesthetics. Analgesics are drugs that reduce  pain, while anesthetics are drugs that deaden pain or cause  loss of consciousness. Over-the-counter analgesics, such as acetylsalicylic acid  (aspirin), acetaminophen (e.g., Tylenol), and ibuprofen (e.g.,  Advil) have few side effects when taken in the correct dosage.  Although some people are allergic to certain analgesics or  may suffer from stomach irritation, flying usually is not  restricted when taking these drugs. However, flying is almost  always precluded while using prescription analgesics, such  as drugs containing propoxyphene (e.g., Darvon), oxycodone  (e.g., Percodan), meperidine (e.g., Demerol), and codeine  since these drugs may cause side effects such as mental  confusion, dizziness, headaches, nausea, and vision problems.  Anesthetic drugs are commonly used for dental and surgical  procedures. Most local anesthetics used for minor dental and  outpatient procedures wear off within a relatively short period  of time. The anesthetic itself may not limit flying so much  as the actual procedure and subsequent pain. Stimulants are drugs that excite the central nervous  system and produce an increase in alertness and activity.  Amphetamines, caffeine, and nicotine are all forms of  stimulants. Common uses of these drugs include appetite  suppression, fatigue reduction, and mood elevation. Some  of these drugs may cause a stimulant reaction, even though  this reaction is not their primary function. In some cases,  stimulants can produce anxiety and mood swings, both of  which are dangerous when flying. Depressants are drugs that reduce the body’s functioning in  many areas. These drugs lower blood pressure, reduce mental  processing, and slow motor and reaction responses. There are  9-8 Drugs several types of drugs that can cause a depressing effect on the  body, including tranquilizers, motion sickness medication,  and some types of stomach medication, decongestants, and  antihistamines. The most common depressant is alcohol. Some drugs, which can be classified as neither stimulants  nor depressants, have adverse effects on flying. For example,  some forms of antibiotics can produce dangerous side effects,  such as balance disorders, hearing loss, nausea, and vomiting.  While many antibiotics are safe for use while flying, the  infection requiring the antibiotic may prohibit flying. In  addition, unless specifically prescribed by a physician, do not  take more than one drug at a time, and never mix drugs with  alcohol because the effects are often unpredictable. The dangers of illegal drugs also are well documented.  Certain illegal drugs can have hallucinatory effects that occur  days or weeks after the drug is taken. Obviously, these drugs  have no place in the aviation community. 14 CFR part 65 prohibits pilots from performing crewmember  duties while using any medication that affects the body in  any way contrary to safety. The safest rule is not to fly as a  crewmember while taking any medication, unless approved to  do so by the FAA. If there is any doubt regarding the effects  of any medication, consult an AME before flying. Scuba diving subjects the body to increased pressure, which  allows more nitrogen to dissolve in body tissues and fluids.  The reduction of atmospheric pressure that accompanies  flying can produce physical problems for scuba divers.  Reducing the pressure too quickly allows small bubbles of  nitrogen to form inside the body as the gas comes out of  solution. These bubbles can cause a painful and potentially  incapacitating condition called “the bends.” (An example  is dissolved gas forming bubbles as pressure decreases by  slowly opening a transparent bottle of carbonated beverage.)  Scuba training emphasizes how to prevent the bends when  rising to the surface, but increased nitrogen concentrations  can remain in tissue fluids for several hours after a diver  leaves the water. The bends can be experienced from as low as  8,000 feet MSL, with increasing severity as altitude increases.  As noted in the Aeronautical Information Manual (AIM),  the minimum recommended time between scuba diving on  nondecompression stop dives and flying is 12 hours, while  the minimum time recommended between decompression  stop diving and flying is 24 hours.  [Figure 9-5] Scuba Diving