San Carlos Mexico Guide

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Chapter Ten: How to Stay Healthy on Your Vacation

Drinking Water

In many parts of Mexico it is not safe to drink the water. In those places, do not drink the water or put ice in your drinks. In high risk locations, do not use tap water even to brush your teeth. Fortunately, in San Carlos the drinking water is not dangerous and should not upset your stomach if taken in small amounts. It is OK to brush your teeth with it. San Carlos water is heavily chlorinated, a little salty and full of chemicals and natural minerals. A little won’t hurt you; many locals drink it regularly with no ill effects. However, you are advised to use bottled water and purified ice for drinking and cooking. Restaurants in San Carlos-Guaymas serve bottled water and pure ice. Do not use tap water for coffee or tea. YUCK!

Diarrhea and Stomach Upsets

Help! I'm on vacation and I have an upset stomach and diarrhea. Is it travelers' diarrhea, food poisoning, or a food allergy?

Travelers’ Diarrhea

“Montezuma’s Revenge” they call it. The nice name is, “travelers’ diarrhea,” and it often occurs when eating in foreign countries. The USA Center for Disease Control (CDC) explains:

Symptoms:  The typical symptoms of traveler's diarrhea (TD) are diarrhea, nausea, bloating, urgency, and malaise. It is rarely life threatening. TD is slightly more common in young adults than in older people. TD is usually acquired through ingestion of fecal matter contaminated food and water. Areas of high risk include the developing countries of Africa, the Middle East, and Latin America.

Duration: TD usually lasts from 3 to 7 days.

Prevention: The best way to prevent TD is by paying meticulous attention to choice of food and beverage. CDC does not recommend use of antibiotics to prevent TD because they can cause additional problems themselves.

The risk of infection varies by type of eating establishment the traveler visits - from low risk in private homes, to high risk for food from street vendors.
When you eat in good restaurants in San Carlos-Guaymas, the water and ice are purified and the food should not make you sick. But, be especially careful in the summer for foods that are not properly refrigerated. Watch out for salsa or other sauces that have been sitting out for hours and seafood that is not absolutely fresh.
Don’t buy prepared food at the Mercado (common market) in Guaymas or anyplace where the food is not refrigerated or heated properly. Avoid taco vendors unless you are sure they are OK. The taco vendors in San Carlos are clean, reliable and make fresh salsa every day- No Leftovers Please!
Locals avoid stomach upsets by putting lime juice on just about everything, (including the beer cans!)

Washing Fruits and Vegetables: When preparing fruits and vegetables at home you should take these precautions:
Soak for 30 minutes in water with a spoonful of Clorox or the commercial product called Microdyn. Rinse.

Treatment of Travelers’ Diarrhea: Visitors to this area are often advised (erroneously) to take Lomotil when diarrhea and nausea strike. The best medical advice is against it. Although antibiotics can be bought over-the-counter in Mexico, don’t do it. One should never take antibiotics except on a doctor’s prescription. This is what you should do:
No coffee, spicy or greasy food
Drink liquids (not alcohol)
Drink Gatorade
Relax and rest

Food Poisoning

Food poisoning, of course, is more serious than TD. The onset is more abrupt and the symptoms more violent.

Onset: 1 - 6 hours. The symptoms of food poisoning usually appear within 1 to 6 hours of consuming the contaminated food.

Cause: Unwashed or improperly handled food, raw fish or meats, or contaminated water can cause food poisoning. The food or water may be contaminated with staphylococcal bacteria. Epidemics of food poisoning are often related to the presence E. coli bacteria.

Symptoms: Food poisoning may cause diarrhea, nausea, vomiting, fever, abdominal pain and headache.

Duration: The symptoms usually disappear in about 12 hours.

This is my non-medical observation: sometimes vacationers over exert themselves in the hot sun, don’t get enough sleep, eat too much, and drink way too much liquor and not enough water. The morning after, when they bemoan their “Montezuma’s Revenge,” it is probably just a hangover, which can be cured by rest and lots of water or Gatorade.

More Severe Intestinal Illnesses


The Centers for Disease Control (CDC) recommend you see a doctor if symptoms of TD or food poisoning do not clear up after three days, or you have the following symptoms:
Bloody diarrhea — a sign of possible E. coli infection, which may lead to kidney failure and death.
Stiff neck, severe headache and fever
Severe diarrhea or vomiting — these can lead to dangerous dehydration. You're probably dehydrated if you haven't urinated for 12 hours.

Bloody Diarrhea

 Bloody diarrhea can occur in cases of Cholera and Dysentery. These illnesses are very unusual in San Carlos, where modern sewage and water treatment are established. The traveler does not need to worry about it in this area, but should be aware of the possibility in some parts of Mexico.

Sea Food Allergy

Definition: Food allergy is an immune response. Normally, your intestinal tract serves as a barrier between foods and your immune system. If you're prone to a food allergy, this barrier fails. When an offending food (allergen) passes through your digestive system, your body forms antibodies specific to the food.
The next time you eat the food you were allergic to, it reacts with these antibodies, triggering an allergic reaction that includes release of histamine and other chemicals.
“Release of these substances can cause a host of uncomfortable symptoms affecting your skin, respiratory system or stomach and intestines.” (Mayo Foundation for Medical Education and Research)
Any food can cause a food allergy. But a few are proven to trigger reactions. The most common offenders are nuts, shellfish (especially shrimp) , whitefish, wheat, milk and eggs.

Onset: Symptoms of food allergy usually appear within two hours.

Anaphylactic Reaction: onset within seconds. It may be only seconds before someone with a severe allergy experiences an anaphylactic reaction. In this life-threatening condition, several parts of the body react simultaneously to the allergen. The airways in the lungs constrict and the soft tissues in the throat swell, making it difficult to breathe. Your heart beats rapidly. To prevent death, immediate medical attention is essential (Mayo Foundation for Medical Education and Research).


Oh dear! I think I’m coming down with the flu, and I have only a 2-week vacation!

Symptoms of flu and colds are similar, but the onset of flu is rapid and the list of symptoms is longer. If you really have the flu, you may just have to spend your vacation in bed.

Definition: A viral infection of the respiratory tract that causes fever , headache , muscle aches , and weakness . There are several types: Influenza B, Influenza A, Asian flu type B; Asian flu type A, and Type C.

Causes: There are three types of influenza virus. All are spread from person to person by inhaling infected droplets from the air. Type A is usually responsible for the large outbreaks and is a constantly changing virus. New strains of Type A virus develop regularly and result in a new epidemic every few years. Types B and C are fairly stable viruses. Type B causes smaller outbreaks, and Type C usually causes mild illness similar to the common cold .

Flu Prevention: Anti-influenza vaccines (flu shots) are recommended annually for people who are 65 years of age or older, anyone with chronic heart or lung conditions. It is a good idea to have a flu shot late in the fall, just before the flu season strikes. (Flu season: November through March) It is best to have your flu shot in the USA or Canada before coming to Mexico.

Onset of Flu: Sudden onset, severity decreases gradually over the next week or 10 days.

Flu Symptoms:
high fever
nasal discharge sore throat
muscle aches and joint stiffness
weakness, fatigue, malaise
nausea & vomiting
chills, sweating, clammy skin

Duration: 7 to 10 days
Symptoms usually go away in 7 to 10 days. To relieve symptoms, try Coriciden-F (F is for flu). If symptoms do not subside, do not hesitate to see a doctor. In rare cases, influenza may affect the heart or cause a severe pneumonia that may be fatal even in healthy adults.

 Common Cold

Definition: A cold is a contagious viral infection of the upper respiratory tract characterized by inflammation of the mucous membranes, sneezing, sore throat, and coughing.

Cause: Colds are caused by over 200 different viruses, known as rhino viruses. Colds are not caused by the same viruses responsible for influenza . Colds spread through droplets from the coughing or sneezing of others with a cold or by hand contact with objects contaminated by someone with a cold.

Onset of Common Cold Gradual onset, peaking on the 3rd day.

Cold Symptoms:
low grade fever (102 F or lower)
nasal congestion; runny nose; sneezing
sore throat
muscle aches

Duration: 7 to 10 days
Home care measures may relieve some of the symptoms of a cold but will not affect the duration of the illness. These measures include over-the-counter pain relievers, drinking plenty of fluids, and rest. Antibiotics are not appropriate treatment for colds.

Insect Bites

Prevention of Insect Bites: The insect pests in this area include ants, bees, wasps, chiggers, no see-ums, flies, spiders, including the Tarantula (which is big and scary looking, but not aggressive or especially dangerous). Tiny flies are a pest although they don’t bite. People call the tiny flies givens, zincates, mantas blancas, gnats or “no see ums”.

To Prevent Insect Bites (in general)
Check the premises:
Put Boric Acid on ant hills
Check the screens
Get rid of standing water outside house
Spray the room with insecticide before bedtime
Stay away from swamps
Do not wear perfume, perfumed soap, shampoo, cologne or after-shave balm
Wear white clothing or natural colors. Bright colors and perfume attract bees
Use insect repellents containing DEET.

Insect Repellents: Turpentine repels insects, but it's toxic. Burning Citronella candles to repel mosquitoes is moderately helpful. Bathe in water with a small amount of chlorine bleach added (1 tablespoon or a little less in a tub of water). Apply Avon Skin So Soft lotion which contains insect repellent. (It doesn’t work for me.)The most effective repellents contain DEET.

Prevention of Insect Bites

Mosquitoes: For prevention, use insect repellent. Apply repellents containing DEET, especially around the ankles.

Gnats and other tiny flies (no see ‘ums”): The Mexicans call those pesky little flies that hang around your face and hands “Bobos.”  They are bothersome for a few weeks in the spring. They don’t bite, just bother. Bobos are attracted to white clothing, so wear a dark cap and shirt if the bugs are bugging you. Look for a breezy place for relief. Discourage them with oil of Pennyroyal (like mint). I have not been able to find Pennyroyal in stores and I have been told it was outlawed by Food and Drug because it was being used to induce abortions??? I have also read that a salve called, “ Autan ” will keep away the no see ‘ums.

Fleas: Try eucalyptus leaves in the bedding as a repellent. Fleas tend to leave a line of bites across the abdomen. If you have fleas in your house, check your pets and treat with flea powder or shampoo.

Sand Fleas look like “no see-ums”, but they do not fly. They bite and leave a red inflamed area which soon begins to itch. The bite looks like a bulls’ eye target. Pierce the center with a sterile needle, apply disinfectant, and apply an anti-itch salve.

Tarantulas – usually live in underground holes, but sometimes they can be seen hanging from palm trees. They look scary, but probably won’t hurt you unless you annoy them.

To Treat Insect Bites
General Treatment: cleanse with soap and water. Apply calamine lotion, ice, baking soda, or Epsom salts.

Specific Treatments for Bites and Stings:

Ants:  Apply “ Sting Stop ”
Bees and Wasps:  Insecticides are not effective against bees and wasps. Swatting makes them aggressive. Just back off and leave them alone. Apply tea bags, tobacco, spit, ashes, match heads, Windex, ammonia, parsley, witch hazel, ice, heat from a hair dryer, Aloe Vera, or baking soda.
Chiggers:  Apply Iodine. Suffocate the chigger in your skin with nail polish, Apply crushed, moistened aspirin.
Ticks:  Remove with tweezers or suffocate with wax, nail polish, oil, shortening; Apply Neosporin.

Methoprene; Eucalyptus leaves

  Prevention: Wrap garbage tightly in can with tight lid so dogs and small wild animals won’t scatter it. Burn Citronella candles on the table. On a patio, hang those electric insect zappers.

  Apply Witch hazel, toothpaste, salt and water, baking soda and water or Echinacea

To Stop Itching
To stop the itching take an oral antihistamine, for example, Benadryl, or use Andantol salve. Andantol may not be available in the US, but is easy to find at local pharmacies. Field Remedy #1 : spit. It really works. Dab some on the bite(s) & repeat when the itching returns. After 3 or 4 applications, the itching stops. Disgusting but effective!

To Relieve Pain
Medicate with Polysporin Plus, which includes a pain killer, or put on Vaseline on skin and then wrap in cloth, or an elastic bandage.
Use Lidocaine to anesthetize skin. It comes in a convenient first aid spray can.

To Soothe the Skin
Vicks Vapo-Rub, Zinc Ointment, PreSun, Alpha Keri bath oil, Aloe Vera gel or other products containing Aloe Vera. A piece of the Aloe Vera plant leaf works very well on minor burns or insect bites.

To Heal Bites and Sores
Some products actually delay healing. Do not use iodine or hydrogen peroxide; these slow the healing.

Little Biting Animals

Centipedes: Live in houses and can get in clothes and bedding and bite. Check the bedding.


Scorpions (Alacran):  Scorpion bites really hurt; children are especially sensitive. Scorpions usually live in fields, in dead trees, under stones, and in hidden recesses and wood piles. However, scorpions sometimes get in houses. They come out after a rain. You may encounter them if you are camping. They may snuggle in your shoes for the night. Their bite is painful and the effects last about 4 hours. Some types of scorpions are dangerous and if a young child is bitten, it could be serious, so take him to a doctor.

Poisonous Toads: There is a dangerous Mexican toad that emerges during damp or humid weather. Their skin exudes a poison that can be fatal to babies and pets. Do no allow children to touch them. Symptoms include rapid, shallow breathing, contracted blood vessels (dogs will have a blue tongue), copious salivation and spasms in the limbs. See a doctor or vet immediately.

Dangerous Sea Creatures:

Sea Urchins


Do not flush the skin with fresh water ; that makes it worse. Sea-urchin spines should be quickly removed. Vinegar dissolves most superficial spines. Soaking the wound in vinegar several times per day and covering the area with a wet vinegar compress is usually sufficient; surgical removal is seldom necessary.
First aid . Treat with lime juice. Control pain. Cleanse the wound with an antiseptic, washing out remaining venom and pieces of spine. Some wounds will require medical attention and antibiotics.

Sting Rays (Manta Raya)

Do not confuse the sting ray with its larger cousin. In English, Manta Ray refers to the large (up to 20 feet) black and white ray, which swims freely, and is harmless. In San Carlos, the local people refer to the sting ray as "Manta Raya." The local sting ray is gray on top, white underneath, and seldom grows to be more than 2 feet across. It lives on the bottom, usually in shallow water. Even very small ones can inflict a painful injury.

Avoid isolated beaches. Playa del Sol, for example, is empty of swimmers and injuries from Sting Rays are common there.
Sting rays hide under a thin layer of sand in shallow water or in crevices, even in tide pools. When you are snorkeling, don’t put your hand in cracks or under rocks. A sting ray could be hiding there. When you enter the water from the beach, shuffle your feet to warn the rays off, and they will swim away.

First Aid
If a person is stung, wash out the injury gently, and remove any piece of the spine that may be visible. Then immerse the part in hot water (do not make it so hot it burns them). Get medical help immediately.
The pain can be severe and be accompanied by bleeding, weakness, vomiting, headache, fainting, shortness of breath. Occasionally the victim may show signs of paralysis or collapse. In addition to receiving medical attention for the pain and any symptoms of shock, it is essential to get medical treatment with antibiotics.
If you have not had a Tetanus shot within the last five years, it is strongly suggested that you get another one. The injury is almost certain to become infected. Mexican physicians are likely to prescribe penicillin, which will help in the short term but may not be sufficient. In All Stings Considered (University of Hawaii Press, Honolulu, 1997), Craig Thomas, MD, recommends injection of ceftriaxone, doxycycline, or coprofloxacin, for serious injuries, cephalexin, doxyclicine or ciprofloxacin administered orally for less severe injuries.

Jelly Fish (man o'war, mal agua)

Jelly fish float on the water or lie on the shore. When a person is brushed by the jellyfish’s thread-like tentacles, they leave a line of thin red welts on the skin and cause an intense burning sensation.

Prevention: People generally have had good luck with SeaSafe (available in dive shops, on the internet, and from the manufacturer, . SeaSafe combines protection from stinging marine animals with sun block. Some people coat their body with Vaseline. When you are swimming, be alert to pale blue bubble-like creatures floating on the water's surface or strewn on the beach and avoid touching them or stepping on them. Wear beach shoes. If you are afraid of jelly fish, do not swim in warm water. Don’t let little children play in the ocean or on the edge of the beach when jelly fish are coming on shore. It hurts them more than it hurts adults.

On some days the jellyfish are worse than other days. They are common during hot weather. Check the beach before you plunge in. The jelly fish are borne ashore by on-shore winds. When the wind shifts, a new colony of jellyfish might blow your way.

First Aid
If you run into a piece of tentacle, do not mash it into the skin by trying to rub it off. Some people can gingerly pick off the tentacle without feeling the stings, but it is better to pick it off with a stick or anything handy, and wash any remnants off with large amounts of water; sea water is fine. DO NOT USE Vinegar or other liquids to wash off the tentacle. A number of studies over the last decade indicate that vinegar, alcohol, urine, or other "folk" remedies may actually trigger nematocyst release, and make the injury more severe.
Our own experience with the Mexican man o'war has been that applying a paste of Adolph's meat tenderizer to the wound after it's been cleaned often helps, but the enzyme papain, which is the active ingredient in Adolph's, has been shown to give mixed results; sometimes the papain triggers the release of any nematocysts still on the skin, and may actually make the injury worse. Practically speaking, minor stings will usually subside within 15 minutes. Treating the injury with ice (10 minutes on, 10 minutes off, for up to an hour) may help ease the pain.
Important: If the person who has been stung shows any signs of respiratory distress, they may be showing the first signs of a severe (anaphylactic) reaction to the venom, and must get medical attention immediately.

Too Much Sun

1. Cool the Body
2. Give Fluids
3. Minimize Shock
Heat-related illnesses include sunburn, heat rash, heat cramps, heat exhaustion and heat stroke. Children are at higher risk for heat related illnesses since their body temperatures rise faster and they sweat less than adults.


Sunburn is caused by over-exposure to sunlight. The risk is increased on the beach and in the water.
Symptoms: redness, swelling and sometimes blistering and pain occur within 6 to 48 hours of exposure.
Prevention: wear loose, cotton long sleeved shirts, long pants and a wide brimmed hat. Thirty minutes before sun exposure apply sunscreen with an SPF of at least 15 or 20, even on cloudy days. When snorkeling, use a waterproof sunscreen. Water magnifies the risk.

Cold Sores

Sun exposure can re-activate herpes simplex cold sores. Acyclovir cream can prevent cold sores if applied early.

Sun Sensitivity

 Be aware of the side effects of some medications which increase your sensitivity to the sun. These medications include: antibiotics, ibuprofen, tranquilizers and anti-diabetes medicines.
Remedies: Aspirin helps calm the heat of sunburn. Calamine lotion or other non-oily lotions will soothe the skin. A very effective treatment is an “After Sun” or other products containing Aloe Vera from sun screen manufacturers.

Heat Rash

Heat rash (prickly heat) typically heat rash appears as a fine rash over the chest. It occurs when the sweat ducts become clogged. Sometimes a rash is an allergic reaction to sun tan lotion. Some medications produce an allergic rash on body parts exposed to the sun. This can also be caused by perfumed lotions and deodorant soaps.
Prevention: Keep the skin dry.
Management: frequent cool (not hot) showers without soap and calamine lotion help.

Heat Cramps

 Heat cramps occur when a person sweats heavily and loses a great amount of salt. It is generally thought that the loss of water and salt from heavy sweating causes the cramps. Heat cramps are muscular pains and spasms due to heavy exertion. They usually involve the abdominal muscles or legs.
First Aid: Get the person to a cooler place and have him or her rest in a comfortable position. Give a half glass of cool water every 15 minutes. Do not let him or her drink too quickly. Do not give liquids with alcohol or caffeine in them, as they can make conditions worse. Loosen clothing and apply cool, wet towels.

Heat Exhaustion

 Symptoms: cool, moist, pale or flushed skin; heavy sweating; headache; nausea or vomiting; dizziness; and exhaustion. Body temperature will be near normal. Heat exhaustion is less dangerous than heat stroke. It typically occurs when people exercise heavily or work in a warm, humid place where body fluids are lost through heavy sweating. Fluid loss causes blood flow to decrease in the vital organs, resulting in a form of shock.
Prevention: To prevent heat exhaustion, drink plenty of water before exercising and avoid working or exercising between the hours of 11 and 3.

Heat Stroke (Sun Stroke)

 Symptoms: include hot, red and dry skin; changes in consciousness, rapid, weak pulse, and rapid, shallow breathing. Body temperature can be very high--sometimes as high as 105 F.

Heat stroke is a life-threatening situation! Help is needed fast. Call your local emergency number. Go to Rescate, the Red Cross or your local doctor.
The victim's temperature control system, which produces sweating to cool the body, stops working. The body temperature can rise so high that brain damage and death may result if the body is not cooled quickly.
First Aid: Move the person to a cooler place. Keep the person lying down. Quickly cool the body. Wrap wet sheets around the body and fan it. If you have ice packs or cold packs, place them on each of the victim's wrists and ankles, in the armpits and on the neck to cool the large blood vessels. (Do not use rubbing alcohol because it closes the skin's pores and prevents heat loss. (American Red Cross)

Sea Sickness

 To avoid seasickness there is a medication that is a big improvement on the Dramamine we used to use. That drug, taken by pill or on a patch, makes a person so sleepy they miss the fun of the trip. The newer drug is called Bonine . It is an inexpensive chewable tablet. Here are some general tips:
Eat a light, non-greasy meal before you go
Get plenty of rest the night before
Snack on ginger snaps and ginger ale
Do not go below into the hold
Face forward, sit still, eyes on the sky
Don’t try to read, knit etc.

 A good health reference is: Wilson, Jane Howarth (1995). Bugs, Bites & Bowels. Connecticut: Globe Pequot Press, PO Box 833, Old Saybrook, CN 06475-0833.