Medical FAQs

Here's a list compiled over the years of commonly asked questions. The list was created by DAN MDs and represent specific, evidence-based recommendations our member should take into consideration.


What do I need to know about diving with a cold sore?
Here are a few issues you should consider
  • Sun exposure or mechanical trauma from the mask and/or regulator may worsen the wound, creating a larger scab and lengthening the healing process.
  • If the sore is bleeding, oozing or otherwise open, the risk of infection by pathogens in the water is significant. Cold sores can become complicated by bacterial infections, so it is important to wash them thoroughly with soap and water and keep them as clean and as dry as possible.
  • If a mask skirt will be placed over the sore in a way that rubs or irritates it, then diving should be postponed. The same is true of the regulator; if holding it would cause irritation, then diving would not be recommended.
  • Dive buddies should review procedures for buddy breathing in an out-of-air situation in light of the fact that cold sores are contagious. If gear is rented, ensure proper decontamination procedures are followed. Although it's unlikely, there is always a chance that resuscitation may be needed. Thus, precautions should be taken to prevent disease transmission. This is normally not an issue because barrier devices are readily available in most first aid kits.
  • Treatments such as penciclovir (Denavir) and docosanol (Abreva) can soften the skin and promote healing. Topical numbing agents such as phenol and menthol may be used for comfort. See your doctor and begin using an over-the-counter product at the first sign of a cold sore; beginning antiviral therapy within the first 48 hours can speed recovery. We recommend you to go back to diving once the treatments are over, there are no more signs and symptoms related to the cold sore and there is total recovery of the ideal psycho-physical conditions.

I’m a SCUBA and apnea instructor. One of my students suffers from an arthritic disorder called psoriatic arthritis and he is being treated with Metotrexate 15mg. I would like to know whether his case represents a contraindication for recreational diving.
The Psoriatic Arthritis is a musculo-skeletal inflammatory chronical disease and it is itself a contraindication for diving as it makes the body vulnerable to decompression stress.

Moreover, the Metotrexate intake could put your student at a further risk for its side effects which includes lung tocixity  and myelotoxicity. Hence you need to have your student’s fit to dive necessarily verified by a specialist in diving and hyperbaric medicine.

I have an allergy to latex. Is "any" part of the diver's equipment made with latex? I am interested in taking up the sport, but if there is any latex involved, I can't.
The overwhelming majority of diving equipment uses either silicone or neoprene rubber. Latex is most often used in what are known as dry suits. These exposure suits have water-tight seals at the neck and wrists.

 This where you would find the majority of latex, but this is not an entry-level issue. There are pieces of accessory equipment that are made of latex, but there are many alternatives that are made of other materials. You have a great deal of control with latex exposure with your own equipment. However, when you are diving from a resort, especially a dive boat, incidental encounters with latex are certainly possible. The severity of your allergic reactions needs to be considered as the best indicator of whether diving would be an appropriate pursuit. Please feel free to contact our medical division if you have any further questions. Also your local dive shops are a good resource for discussing specific equipment issues.

Our 12-year-old daughter has shown a great deal of interest in learning to dive and as a family, we have just experienced an introductory dive at our local dive shop. At our daughter’s recent physical exam, her pediatrician expressed some concern for her bone growth and scuba diving. It seems there are many youngsters involved in diving. Should we be concerned for our daughter’s growth and development if we decide to allow her to dive?
In general, the concern is focused on the possible formation of micro-bubbles in the bloodstream of all scuba divers. We often call these ‘silent bubbles’, which fail to produce any detectable symptoms, but are known to be present in the bloodstream of many divers.

No one knows to what extent these bubbles could form in younger divers.
Theoretically, these bubbles may obstruct blood flow in nutrient vessels to the epiphyseal plates, also called growth plates.
This process may cause focal areas of avascular necrosis or angular deformity to the developing weight bearing long bones, particularly the femoral head, distal femur, and proximal tibia. Young divers should stay within the guidelines of the junior divers program.
This will limit their exposure to nitrogen, by restricting depth, time and number of dives as well as allowing for maximum surface intervals to promote nitrogen off gassing.
Although the concern is theoretical, conservative dive practices are recommended for junior divers.

My wife and I love to travel to exotic destinations, and my previous doctor used to give me antibiotics in case I got sick in a remote location. I have a new primary care physician who is hesitant to do this. What does DAN recommend?
For some time now prescribing guidelines regarding antibiotic use for various conditions have favored a much more conservative approach due to increasing antibiotic resistance. Many illnesses are viral in nature, and antibiotics are of no benefit in these cases.

If you get sick while traveling, a local physician is your best resource; he or she will be aware of the common pathogens that cause problems in the area you are visiting.
When traveling, your best defenses against illness are handwashing, careful sourcing of water and food, getting relevant travel immunizations and taking appropriate precautions in areas where mosquitoes and other living organisms can transmit infectious diseases to humans. Talk to your doctor or visit a travel medicine clinic if you will be going to a region in which medical care is lacking.

The doctor can advise you about any medications you should take with you and when to use them.

My doctor recently put me on Coumadin. Could diving while taking this medication cause me any problems?
There is a well-recognized risk for uncontrolled bleeding in people who are being treated with anticoagulant medications such as Coumadin. However, many people who take anticoagulants — including divers — have carefully adjusted their prothrombin times and with appropriate behaviors may not be at undue risk.

Some physicians believe diving is an unnecessary risk for their patients who are taking anticoagulants and will advise against diving, but DAN is unaware of any data indicating that sport divers face an increased risk of complications. 

Some physicians trained in dive medicine may be willing to endorse recreational diving for these patients provided:

  • The underlying disorder or need for anticoagulants does not put the patient at increased risk of an accident, illness or injury while diving
  • The patient understands the risks and modifies his or her dive practices to reduce the risk of ear, sinus and lung barotrauma as well as physical injury. This includes avoiding forceful equalization — equalization must come easily for these people
  • The patient dives conservatively, planning short, shallow profiles to reduce the risk of decompression illness, which can involve bleeding in the inner ear or spinal cord
  • The patient avoids diving in circumstances in which access to appropriate medical care is limited
  • DAN medics are available for consultation with you or your doctor; don’t hesitate to give us a call

I've recently been diagnosed with Raynaud's Syndrome. I'm an avid diver. Can I continue diving?
Raynaud's Syndrome decreases effective blood flow to the extremities, most significantly fingers and toes; this results in cold, pale fingers and toes, followed by pain and redness in these areas as blood flow returns.

The underlying problem is constriction of the blood vessels in response to cold, stress or some other phenomenon supplying these areas.
Symptoms are often mild.
Raynaud's phenomenon may occur as an isolated problem, but it is more often associated with autoimmune and connective tissue disorders such as scleroderma, rheumatoid arthritis and lupus. Raynaud's Syndrome poses a threat to a diver who is so severely affected that he/she may lose function or dexterity in the hands and fingers during the dive. If coldness is a trigger that causes symptoms in the individual, immersion in cold water will likely do the same.

These individuals should avoid diving in water cold enough to elicit symptoms in an ungloved hand.
The pain may be sufficiently significant that, for all practical purposes, the diver will not be able to use his/her hands. Less severely affected individuals may be able to function adequately in the water. Calcium channel blockers may be prescribed for individuals with severe symptoms; lightheadedness when going from a sitting or supine position to standing may be a significant side effect.

Is it possible to dive after having suffered a stroke?
Stroke, or loss of blood supply to the brain, causes damage to part of the brain, or bleeding from a blood vessel in the brain, which results in similar injury. Strokes vary in severity and the resulting disability depends on the size and location of the event.
  1. Most strokes occur in older people. The stroke itself identifies the person as one who has advanced arterial disease, thus a higher expectation of further stroke or heart attack.
  2. The extent of disability caused by the stroke (e.g., paralysis, vision loss) may determine fitness to dive.
  3. Vigorous exercise, lifting heavy weights and using the Valsalva method for ear-clearing when diving all increase arterial pressure in the head and may increase the likelihood of a recurrent hemorrhage.
  4. While diving in itself entails exposure to elevated partial pressures and elevated hydrostatic pressure, it does not cause stroke.
  5. There is certainly increased risk in diving for someone who has experienced a stroke. Exceptional circumstances may exist, such as cerebral hemorrhage in a young person in whom the faulty artery has been repaired with little persisting damage.
    This type of recovery may permit a return to diving, with small risk. Each instance, however, requires a case-by-case decision, made with the advice of the treating physician, family and diving partners. Consulting a neurologist familiar with diving medicine is also advisable.
  6. There is a similar concern for significant residual symptoms, as with post brain tumor surgery.

I was diagnosed with an ailment called Arteritis Temporalis 10 months ago and was treated with a high dose of Prednisone (or cortisone) (60mg/day). The dosage of prednisone is being diminished each month. Now it is down to 15 mg/day and I am feeling OK. Is this a contraindication for recreational diving? Should I restrict my dives to 20-meter maximum?
For what concerns recreational scuba diving, not much is known about the interaction of cortisone, giant-cell arteritis (also known as temporal arteritis) and diving. In such cases it is wise to be prudent.

I do not think major problems are to be expected, but believe that limiting the depth and dive times are wise decisions.

Last year in October, I was hospitalized for acute coronary artery disease, treated with a coronary angioplasty and DES (Drug Eluting Stent) implant. The angiographic results were excellent, without any complications. My echocardiogram, which upon admission showed apical hypokinesia, upon dismissal showed normalization of all hypokinetic segments. I had my first routine check-up in the month of February with an ECG test, and a second check-up in May with CPET. The results were the following: the test was negative, and maximal exercise testing, after suspension of Metoprolol, was also negative for inducible myocardial ischemia. Are there any contraindications for diving activities?
The missing step to the clinical tests and check-ups that you have already performed, is an appointment for a medical with a hyperbaric trained physician, who can assess your fitness to dive.

In addition, concerning the type of dives that you will be able to perform from now on, you will surely have to avoid strong currents and cold water dives, and should limit yourself to purely recreational diving, which means a maximum depth of 30 m, and No-Deco.

I have to teach an OWD course to a student who has silicone breast implants. I would like to know if there are any contraindications to diving due to depth (pressure) and to nitrogen being absorbed by the silicone.
There is not a lot of information on the durability of silicone implants when diving. What is known basically refers to breast implants, and generally states that they are safe and reliable. The specific precautions to be taken are generic and mechanical.

The - actual and common - possibility that inert gas bubbles could form inside the implants, does not appear of considerable importance, since this phenomenon would remain limited to the inside of the implant, and therefore without causing any damage.
This applies both to implants made only of silicone, and to saline implants.

There is no information of statistic or scientific interest regarding soft tissue fillers, or injectable implants, even if theoretically, there could be the risk of a localized production of bubbles at a different rate from surrounding tissues.

However, considering that the filler is injected into the tissue and is free to move in the surrounding areas, it is possible that a gas exchange will take place, but with a non significant risk of damage.

I have breast implants. I would like to learn to dive but am afraid of what the pressure will do to the implants. Are there any studies on this?
Three types were tested: silicone-, saline-, and silicone-saline-filled. In this experiment, the researchers simulated various depth/time profiles of recreational scuba diving. There was an insignificant increase in bubble size (one to four percent) in both saline and silicone gel implants, depending on the depth and duration of the dive.

The silicone-saline-filled type showed the greatest volume change.

Bubble formation in implants led to a small volume increase, which is not likely to damage the implants or surrounding tissue. If gas bubbles do form in the implant, they resolve over time.

Once sufficient time has passed after surgery, when the diver has resumed normal activities and there is no danger of infection, she may begin scuba diving.

Breast implants do not pose a problem to diving from the standpoint of gas absorption or changes in size and are not a contraindication for participation in recreational scuba diving. Avoid buoyancy compensators with constrictive chest straps, which can put undue pressure on the seams and contribute to risk of rupture.

I'm concerned about diving as I get older. Will the bone loss from osteoporosis make a difference in my diving?
To date, we have not had significant pool of women who: are post menopausal and at risk of osteoporosis (menopause average at 50, osteopenia at 60-65, and fractures starting at 70-75) or have a significant diving experience including appropriate number of dives at profound depth which put them at risk for osteonecrosis

Therefore, we have no data on coincident osteoporosis and osteonecrosis in women at risk (or men for that matter).

The pathophysiologic mechanisms leading to osteoporosis and osteonecrosis are different.

Osteoporosis results from decreases in osteoblast activity and relative increase of osteoclast activity, resulting in bone resorption and demineralization.
The infarction of the microcirculation of bone is the triggering mechanism for osteonecrosis. Women are at increased risk for osteoporosis given that their overall lifetime peak bone mass is lower than men and that the loss of estrogen during menopause, greatly accelerates the rate of bone demineralization.

All we can say at this point is that women should dive as conservatively as possible, thereby trying to minimize their risks of osteonecrosis, so as not to impose this bone damaging disease on top of their already increased risk of fracture due to Type I estrogen dependent osteoporosis.

I have been invited to a diving weekend on El Hierro, Spain. The accommodation where the divers are staying however is at about 1000 mt altitude. There will be 2-3 dives per day, varying depths, all well within limits. What the minimum surface interval should be before ascending to the accommodation?
Be aware that a change of altitude post dive, in excess of approximately 700m is considered carrying the same risk as flying after diving. As your transition will be of 1000m then this applies to you.

The most prudent is to leave 24 hours before flying or going to high altitude, but the minimum guidelines established by DAN and the Undersea and Hyperbaric Medical Society for flying/altitude (Sheffield and Vann 2004) are:

  • A single dive within the no-decompression limits: 12 hours
  • Repetitive dives or multiple days of diving: 18 hours
  • Decompression dives (planned or unplanned): substantially greater than 18 hours


This means that, with 2-3 dives a day you would be required to wait at least 18 hours.
Since this seems impossible to do, you are strongly advised to either restrict your diving to a single dive daily, to permit yourself an adequate surface interval, or change accommodation.

During my last dive, I hit a sea urchin and the spines went in my thigh. I wasn't able to remove all of them so I just let it heal thinking they would just fall off but, until now, the spines are still inside and sometimes my thigh swells up. Can you please let me know what I can do?
If the spines are only small fragments then the body will eventually absorb them.

If they are large then it would be best to go to a doctor to remove them as otherwise they will cause a foreign body granuloma which, although not a problem of health concern, may leave a noticeable ‘bump’ in the skin.

Four days ago I came into contact with a jellyfish in the Mediterranean Sea. At the pharmacy I was advised to use Flubason 0.25%, desoximetasone skin cream, but it doens't seem to do much in terms of relieving irritation and itchiness. Is there something I can do to help the healing process?
The normal therapy, in such cases, is always and mainly based on the use of local cortisone-based ointments or creams, and in addition, on the use of antibiotic preparations if there's the risk of an infection, but this does not seem to exist in your case.

It is quite common for the itching and discomfort to last for a few days, in spite of the cure. If it is too annoying, you could ask your doctor to prescribe a cortisone-based ointment with a higher concentration, and for the itchiness, you might consider (obviously only on prescription) an anesthetic cream for local use (xylocaine or lidocaine based).

When trying to provide rescue breaths in the water to an injured diver, why can’t I use my spare regulator’s purge button? That seems easier to me than trying to manage a pocket mask
Using the purge button of a second-stage regulator has been proposed many times, but any advantage it may seem to offer does not outweigh the potential risks and complications. If the regulator mouthpiece is not already in the unconscious diver’s mouth, trying to replace it can be difficult and time consuming.

Without a good seal and a means to occlude the diver’s nostrils, any attempts to ventilate will be unsuccessful. Even if the mouthpiece can be successfully placed in the diver’s mouth there is a risk of it pushing the relaxed tongue to the back of the throat and blocking the airway.
If the regulator mouthpiece remained or was placed in the diver’s mouth without blocking the airway, the next challenge would be administering air.

Purge buttons do not have any true regulatory capability. They effectively override the second stage’s function of stepping down gas from intermediate pressure to ambient pressure and thereby deliver intermediate-pressure gas directly from the first stage.
Delivering breathing gas to the lungs at too high a pressure may overinflate them, potentially leading to serious injury.
If the diver’s airway is not maintained in an open position, the breathing gas delivered by the purge button could be forced into the stomach, causing gastric distention.
This places the diver at risk for regurgitation, which can further compromise the airway and lead to aspiration.

Delivering rescue breaths using a pocket mask or similar method provides tactile feedback via changes in pressure required to ventilate the lungs; supplying rescue breaths with the purge valve eliminates this important feedback. Using a regulator’s purge valve also precludes the option of supplementing the gas with 100 percent oxygen.
Rescue methods that are currently taught by dive-training agencies are the result of years of practical experience.
Purge valves were never designed to function as rescue equipment. When ventilating an injured diver, rely on established methods

I would like to know if deep stops are always recommended for recreational dives, if the depth of the deep stop must be half of the maximum depth reached or half of the maximum pressure reached, and if, for multi-day dives, it is always recommended to do this deep stop
The introduction of a deep stop at half of the maximum depth reached during recreational dives during the ascent phase seems to:
  • significantly decrease inert gas bubbles detected by a Doppler scan after a dive
  • reduce tension of inert gas in ‘fast’ tissues, which is an important fact to correlate with gas exchange happening in the spinal chord. 

Authors of scientific publications regarding this topic concluded that a deep stop can decrease the likelihood of suffering from decompression sickness.

I am writing to you to have some information about the compatibility of trombophilia and scuba diving. My partner, who is a diver like me, after running some routine tests, discovered that she has trombophilia (mutation C677T in the gene MTHFR in homozygosity). Provided that she is 41 years old, a non-smoker, leads a healthy life, practices sports, and has never had cardiovascular thrombotic events so far, I would like to know if she will be able to continue performing diving activities from now on.
In order to understand if there is an actual risk or only a potential risk of thromboembolic events connected to the mutation carried by your partner, we advise you to complete a thromboembolic risk evaluation carried out by an hematologist.

Theoretically, your partner may be more susceptible to decompression illness, and therefore, we advise you to reduce any risks by taking appropriate precautionary measures with regard to dive profiles.

The following are the characteristics of dive profiles with the lowest production of bubbles: 

  • do not plan dives with compulsory decompression stops
  • avoid, as much as possible, repetitive dives, or if you wish to dive repetitively, make sure your surface intervals are long enough (not less than 3 hours, and best if longer)
  • limit your bottom time to no more than 70% of the No-Deco time indicated by your computer upon reaching maximum depth, or as suggested by your dive tables
  • perform your dive by reaching maximum depth right at the start and then “ascending”, and avoid staying at shallow depths and then going deeper again
  • if your dive computer allows advanced settings, set the GF Low to less than 30 and the GF High to 70
  • if possible, use enriched air mixes and set your computer or use dive tables as if you were diving on air

I have recently had a defibrillator implanted by my doctor. After I recover, what are my chances of going back to diving? I am told that it works as a pacemaker too
These implantable devices have been found to benefit patients at a high risk of ventricular tachycardia, ventricular fibrillation, or other rhythm defects that can lead to sudden cardiac arrest. The pacemaker feature will increase the heart rate of the patient if it slows to an inefficient rate. With or without the pacemaker feature, these internal devices are used to treat potentially life-threatening rhythms.

It is the opinion of diving medicine professionals that due to this potential life threat, individuals with these implanted devices are disqualified from diving.

These devices are intended to prevent sudden cardiac arrest, but the heart itself may be in generally poor health which is not compatible with safe diving. As relaxing as diving is there is still an increased work-load placed on the heart.
The heart needs to be able to respond effectively to any increased exercise demand, especially in an emergency situation.

A heart that is prone to life-threatening rhythms has most likely sustained injury from coronary artery disease or other conditions that affect the muscle tissue of the heart, or its electrical pathways. Any exercise restrictions from the diver’s cardiologist would be a good indicator that diving would hardly be in their best interest.

Showing 1 to 20 of 60 entries.