Key takeaways

  • Plan sun protection for a doxycycline course. NHS Specialist Pharmacy Service lists it alongside ciprofloxacin, metronidazole and tetracycline as a medicine that can increase sensitivity to sunlight. SPS
  • Use broad-spectrum SPF 30 or higher, protective clothing and a hat. Avoid sun exposure where possible. SPS
  • A severe skin reaction needs review. Continuing with more careful sunscreen use is not enough. SPS
  • Check the storage instructions on your pack. Heat affects the medicine as well as the person taking it. SPS recommends cool, dry storage away from direct sunlight, subject to the manufacturer’s conditions. SPS
  • Use antibiotics for the infection they were prescribed for. Taking an antibiotic unnecessarily or using the wrong type contributes to resistance. WHO

Why does it matter so much in the sun?

Doxycycline can make a short spell in the sun produce an exaggerated sunburn reaction.

The label describes this reaction in some people taking tetracyclines. NHS Specialist Pharmacy Service lists doxycycline, ciprofloxacin, metronidazole and tetracycline in its photosensitivity advice. Its precautions are concrete: avoid the sun where possible, wear protective clothing and a hat, and use broad-spectrum sunscreen of SPF 30 or higher. Severe skin reactions need review. SPS

Practically, for the duration of the course and for a short period after:

  • Treat midday sun as off-limits rather than merely uncomfortable.
  • Use broad-spectrum sunscreen properly, and reapply it.
  • Cover up, including on the tops of the feet, the back of the neck and the ears, which people routinely forget.
  • Be careful around water and pale surfaces, which reflect a great deal.
  • Do not use tanning beds during the course.

Keep these precautions for a short chest-infection course too. Acne treatment or malaria prophylaxis can mean months of protection. SPS also asks clinicians to consider the person’s access to cooling and water, pregnancy, kidney disease and other medicines when assessing heat risk. The antibiotic is only part of that assessment. SPS

How should I actually take it?

With plenty of fluid, sitting or standing upright, and not immediately before lying down.

The label instruction is to drink fluids liberally along with doxycycline to reduce the risk of oesophageal irritation and ulceration. That risk is the reason for the posture rule as well: a capsule or tablet that lodges in the gullet rather than reaching the stomach can cause a painful ulcer there.

So in practice:

  • Take it with a full glass of water, not a sip.
  • Stay upright for a while afterwards rather than going straight to bed.
  • If a dose is due at bedtime, take it well before lying down.

Symptoms that suggest the gullet has been irritated are pain or difficulty on swallowing, or pain behind the breastbone. Those are worth reporting rather than enduring.

Whether to take it with food depends on the specific product, since some preparations differ, so follow the instructions you were given with yours. Alcohol is not the main concern described here, but ask the prescriber about your own situation, particularly during a long course.

Who should not take it?

Children whose teeth are still developing, and it needs care in pregnancy.

The tetracycline class, used during tooth development, may cause permanent discolouration of the teeth, yellow-grey-brown. The label defines that period as the last half of pregnancy, infancy and childhood to the age of 8 years.

On pregnancy specifically, the label notes that evidence of embryotoxicity has been seen in animals treated early in pregnancy, that there are no adequate and well-controlled studies in pregnant women, and that if a tetracycline is used in pregnancy or a patient becomes pregnant while taking it, she should be told of the potential hazard to the foetus. That is a conversation with a doctor, not a decision to make from a leaflet.

Other things to raise with your prescriber before starting: any previous reaction to a tetracycline, difficulty swallowing or a history of oesophageal problems, and any other medicines you take.

What is it actually used for?

Doxycycline treats several bacterial infections and also has longer-course uses in acne and malaria prevention.

Doxycycline is active against a broad set of bacteria, which is why it appears in so many different situations: chest infections, skin and soft tissue infections, some sexually transmitted infections, and several less common infections including tick-borne ones.

Two uses run much longer than a typical antibiotic course:

  • Acne, where it is used for its effect on inflammation as well as bacteria, over months rather than days.
  • Malaria prophylaxis, where it is taken before, during and after travel to a malaria area. That use is covered in malaria prophylaxis.

Both of those long courses intersect with the sun problem, which is why the photosensitivity precaution needs to become a habit rather than a one-week inconvenience.

The label also states the resistance principle directly: doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria, in order to reduce the development of drug-resistant bacteria and maintain the effectiveness of doxycycline and other antibacterial drugs. WHO reports that 1 in 3 reported infections in the Eastern Mediterranean and South-East Asia regions were resistant in its global antibiotic-resistance summary. That is a regional surveillance figure, not a doxycycline failure rate. WHO See antibiotics and resistance.

Do and don’t

Do:

  • Take it with a full glass of water and stay upright afterwards.
  • Use sun protection and avoid midday sun for the whole course.
  • Tell your prescriber if you are pregnant or might become pregnant.
  • Report painful or difficult swallowing.
  • Complete the course you were prescribed.

Don’t:

  • Don’t take it lying down or right before bed.
  • Don’t give it to a child under 8 unless a doctor has specifically decided to.
  • Don’t assume a short course means the sun precaution does not apply.
  • Don’t use it for a cold or flu; it does nothing against viruses.
  • Don’t keep leftovers for a future illness.

Match a prescribed course by its active ingredient and strength.

The antibiotics category lists what is stocked here, and the ingredients index maps active ingredients to the brands containing them. The wider argument about using antibiotics properly is in antibiotics and resistance, and the malaria-prophylaxis use is covered in malaria prophylaxis.

MedicForce option: our antibiotic listings show active ingredient and strength, so a course prescribed elsewhere can be matched precisely.

Label statements quoted above are from the approved product information for doxycycline.