Doxycycline 100 mg dispersible tablets – patient leaflet, side effects, dosage

1. What Doxycycline monohydrate is and what is it used for

Doxycycline 100 mg dispersible tablet contains the active substance doxycycline as doxycycline monohydrate. Doxycycline is an antibiotic belonging to a group of medicines called tetracyclines. It is used to treat many different types of infections including:

• Chest, lung or nasal infections e.g., bronchitis, pneumonia, sinusitis
• Urinary tract infections (the passage through which urine passes) e.g., cystitis, urethritis
• Acne (a skin condition)
• Eye infections
• Sexually transmitted diseases e.g., gonorrhoea, syphilis, chlamydia
• Fevers associated with louse or tick bites
• Malaria, when chloroquine is not effective

Doxycycline is also used to prevent certain infections developing, these are scrub typhus (a disease carried by small insects) Rocky Mountain spotted fever, travellers' diarrhoea, malaria and leptospirosis (a bacterial infection).

Your doctor may want you to take doxycycline to treat another infection not listed above. You may also be prescribed an additional medicine to take with doxycycline to treat your infection. You must talk to your doctor if you do not feel better or if you feel worse.

2. What you need to know before you take Doxycycline monohydrate

Do not take doxycycline:

• if you are allergic to doxycycline or any other tetracycline antibiotic or any of the other ingredients of this medicine (listed in section 6)
• if you are pregnant or trying to become pregnant
• if you are breast feeding

You should not use doxycycline during periods of tooth development (pregnancy, infancy or in children below 8 years old) as such use may lead to permanent discolouration (yellow-grey-brown).

There may be circumstances (e.g., severe or life-threatening conditions), where your physician may decide that the benefits outweigh this risk in children below 8 years and doxycycline should be prescribed.

Warnings and precautions

Talk to your doctor or pharmacist before taking doxycycline if any of the following apply to you:

• you are likely to be exposed to strong sunlight or uv light (e.g. on a sun bed). You should avoid exposure to strong sunlight while taking this medicine as your skin may be more sensitive to sunburn than normal.
• you have kidney or liver problems.
• you have myasthenia gravis (a disease which causes unusual tiredness and weakness of certain muscles, particularly in the eyelid).
• you have an immune system disease that causes joint pain, skin rashes and fever (systemic lupus erythematosus). The condition may be worsened by taking doxycycline.
• you have porphyria (a rare disease of blood pigments).
• you have (or have ever had) systemic lupus erythematosus (an allergic condition that causes joint pain, skin rashes and fever). This condition may be worsened by taking doxycycline.
• you are suspected as having syphilis. Your doctor will continue to monitor you after your treatment has stopped.
• you have diarrhoea or usually get diarrhoea when you take antibiotics or have suffered from problems with your stomach or intestines. If you develop severe or prolonged or bloody diarrhoea during or after using doxycycline tell your doctor immediately since it may be necessary to interrupt the treatment. This may be a sign of bowel inflammation (pseudomembranous colitis) which can occur following treatment with antibiotics.
• you are taking oral retinoids as there is a higher risk of suffering from increased pressure in your skull (severe headache with change in vision) when taken with doxycycline.

When used for a long duration, doxycycline may cause infections that cannot be treated with this antibiotic. Your doctor can explain the signs and symptoms of such types of infection.

Other medicines and doxycycline

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines

(including medicines you have obtained without a prescription). If you are taking any of the medicines listed below tell your doctor before taking doxycycline. Some medicines can reduce the effectiveness of doxycycline, these include:

• Antacids (indigestion remedies), iron preparations, oral zinc or bismuth. These should not be taken at the same time of day as doxycycline.
• Carbamazepine, phenytoin (medicines used to control epilepsy) and barbiturates (used to control epilepsy or as a sedative).

Doxycycline can affect the action of some other medicines, these include:

• Increased action of warfarin or coumarins (used to prevent blood clots)
• Reduced effectiveness of oral contraceptives (birth control pills)
• Reduced effectiveness of penicillin antibiotics (used to treat infections)
• Increased blood levels of ciclosporin (a medicine used to affect the body's immune response)

If you are going to have a general anaesthetic for an operation or dental surgery you must tell your anaesthetist or dentist that you are taking doxycycline as you may have more side effects.

Taking doxycycline with food, drink and alcohol

Please see section 3 How to take Doxycycline monohydrate. Alcohol may reduce the effect of doxycycline and should be avoided.

Pregnancy and breast-feeding

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby ask your doctor or pharmacist for advice before taking this medicine.

Doxycycline must not be taken if you are pregnant or breast-feeding.

Driving and using machines

This medicine should not affect your ability to drive or use machines.

Excipient warning

Doxycycline contains sodium

• This medicine contains less than

  1 mmol sodium (23 mg) per tablet,

  that is to say essentially 'sodium-free'

3. How to take Doxycycline monohydrate

Always take this medicine exactly as your doctor or pharmacist has told you to. Check with your doctor or pharmacist if you are not sure.

• Take Doxycycline dispersible tablets by letting the tablet break up in a small amount of water. Do not swallow the tablet without letting it break up in water first.
• It is best to take your tablets at the same time(s) each day, when sitting or while standing.

• It is important not to lie down for at least thirty minutes after taking Doxycycline tablets, so that the tablet can move as swiftly as possible into the stomach and prevent irritation of the throat or oesophagus

  (canal taking food from the

  mouth to the stomach).

• For the treatment of infections, Doxycycline tablets can be taken with or without food.
• For the treatment of acne, it is recommended to take Doxycycline tablets with food or a drink.
• If Doxycycline tablets upsets your stomach then taking it with food or milk is recommended.

The recommended doses are shown in the list below. These are the different doses that your doctor may prescribe depending on the infection being treated.

• Usual Dose (Chest, lung or nasal, urinary tract, eye and other infections) 2 tablets on the first day, then 1 tablet daily.

The length of treatment is dependent on the infection being treated.

Children aged 8 years to less than 12 years

Doxycycline for the treatment of acute infections in children aged 8 years to less than 12 years should be used in situations where other drugs are not available or are not likely to be effective. In such circumstances, the usual doses are:

For children 45 kg or less

First day: 4.4 mg for each kg of bodyweight (in single or 2 divided doses) then 2.2 mg for each kg of bodyweight (in single or 2 divided doses) from the second day. The length of treatment is dependent on the infection being treated.

In more severe infections, up to 4.4 mg for each kg of bodyweight should be given throughout treatment.

For children over 45 kg

Dose administered for adults should be used; 200mg on the first day, then 100 mg daily. The length of treatment is dependent on the infection being treated.

Adults and children aged 12 years to less than 18 years

200mg on the first day, then 100 mg daily. The length of treatment is dependent on the infection being treated.

• Acne

  Half a tablet daily for 6-12 weeks, with food or a drink.

• Sexually Transmitted Diseases

  1 tablet twice daily for 7 - 10 days.

• Primary and Secondary Syphilis

  2 tablets twice daily for 2 weeks. Your doctor will continue to monitor you after your treatment has stopped.

• Fevers associated with louse or tick bites Single dose of one or two tablets depending on severity.

011225

• Treatment of malaria, when chloroquine is not effective

  2 tablets daily for at least 7 days.

• Prevention of malaria

  1 tablet daily from 1-2 days before travelling to a malarial area until 4 weeks after returning.

• Prevention of scrub typhus

  Single dose of 2 tablets.

• Prevention of travellers' diarrhoea

  1 tablet twice daily on the first day of travel, followed by 1 tablet daily throughout the stay in the area. If you are planning to take these tablets for more than 21 days, please consult your doctor.

• Prevention of leptospirosis

  2 tablets once each week during the stay in the area; 2 tablets on completion of the trip. If you are planning to take these tablets for more than 21 days, please consult your doctor.

You should start to feel better within a few days. If you have been given doxycycline for acne it may be a few weeks before you start to see an improvement. If your infection gets worse or you do not start to feel better within a few days (except for acne), or a new infection develops, go back and see your doctor.

Treatment of Rocky Mountain spotted fever

Adults: 100 mg every 12 hours.

Children: weighing less than 45 kg: 2.2 mg/kg body weight given twice a day. Children weighing 45 kg or more should receive the adult dose.

Patients should be treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement. Minimum course of treatment is 5-7 days.

If you take more doxycycline than you should

If you take too much doxycycline contact your doctor or nearest hospital immediately. Always take the labelled medicine package with you, whether there is any doxycycline left or not.

If you forget to take doxycycline

If you forget to take a tablet take it as soon as you can. Take your next tablet at the right time. Do not take a double dose to make up for a forgotten dose.

If you stop taking doxycycline

If you stop taking the tablets too soon, the infection may return. Take the tablets for the full time of treatment, even when you begin to feel better.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, this medicine can cause side effects although not everybody gets them.

Stop taking this medicine and tell your doctor immediately if you experience any of the following serious side effects after taking this medicine. Although they are very rare, the symptoms can be severe.

• Sudden wheeziness, difficulty in breathing, chest pain, fever, swelling of eyelids, face or lips, rash or itching (especially affecting the whole body).
• Upset stomach, loss of appetite, severe, persistent or bloody diarrhoea (this may occur up to two or three months after the last dose and may be associated with stomach pain or fever). This may occur after treatment with antibiotics and can be a sign of serious bowel inflammation.
• Fever, swollen lymph nodes or skin rash. These may be symptoms of a condition known as DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) and can be severe and life- threatening.
• Very severe headache which may be associated with visual disturbances such as blurred vision, double vision or loss of vision. Permanent visual loss has been reported. The possible symptoms in benign intracranial hypertension include headache, vomiting, visual disturbances including blurred vision, a localised defect in the visual filed bordered by an area of normal vision (scotoma), double vision (diplopia), and possible vision loss, in some cases, even permanent.
• Serious illness with widespread severe blistering of the skin, mouth, eyes and genitals.

If any of the side effects listed below occur, contact your doctor as soon as possible.

• The Jarisch-Herxheimer reaction which causes fever, chills, headache, muscle pain, and skin rash that is usually self-limiting. This occurs shortly after starting doxycycline treatment for infections with spirochete such as Lyme disease.
• Skin that is more sensitive to sunlight than normal. You may get a skin rash, itching, redness or severe sunburn. If this happens stop taking the medicine and tell your doctor.
• Inflammation and/or ulcers of the gullet.
• Blood disorders. These are due to changes in numbers of different cell types in the blood. Symptoms may include tiredness, easy bruising or infections.
• Low blood pressure.
• Increased heart rate.
• Aches in the joints or muscles.
• Stomach pain and diarrhoea.

The side effects listed below may go away during treatment as your body adjusts to the medicine. Tell your doctor if any of these side effects continue to bother you:

Common: may affect up to 1 in 10 people

• feeling or being sick
• worsening of a disease called systemic lupus erythematous (SLE). This is an allergic condition which causes joint pain, skin rash AND fever headache
• pericarditis (inflammation affecting the heart)

Uncommon: may affect up to 1 in 100 people

• heartburn

• vaginal infection

  Rare: may affect up to 1 in 1,000 people

  • anxiety
  • difficulty in swallowing, sore or painful tongue or mouth
  • skin reddening (flushing)
  • a ringing or buzzing noise in the ear
  • soreness and itching of the rectal and/or genital area
  • inflammation of the bowel
  • bulging fontanelles (soft spot on head) of infants
  • increased pressure in the skull (severe headache with change in vision)
  • inflammation and damage to the liver
  • abnormal liver function tests
  • discolouration of the thyroid tissue when given for long periods. The medicine does not impair thyroid function
  • round or oval patches of redness and swelling of the skin which reappear at the same site each time the medicine is taken (fixed eruption)
  • darker patches on your skin.
  • loosening of the nail from the nail bed after exposure to the sun
  • increased levels of urea in the blood
  • yellow skin and eyes (jaundice), inflammation of the pancreas
  • upset stomach, loss of appetite, diarrhoea (this may occur up to two or three months after the last dose), stomach pain

Not known: frequency cannot be estimated from the available data

• discolouration and/or lack of growth of teeth

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Doxycycline monohydrate

Keep this medicines out of the sight and reach of children.

This medicinal product does not require any special temperature storage conditions.

Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help to protect the environment.

If your tablets become discoloured or show any other signs of deterioration, consult your pharmacist who will tell you what to do.

6. Contents of the pack and other information

What Doxycycline monohydrate contains

The active substance(s) is

Each Tablet contains Doxycycline monohydrate equivalent to 100mg of Doxycycline.

The other ingredients are: Microcrystalline Cellulose, Povidone (PVP K30), Sodium Starch glycollate (Type A), Purified Talc, Colloidal anhydrous silica, Magnesium Stearate

What Doxycycline monohydrate looks like and contents of the pack

Yellowish-green circular, biconvex tablets having Diameter 9.0 - 9.2 mm, with inscription '100 DOXY' on one side and 'DISP' with breakline on other side.

Dispersible Tablets are packaged in Blister containing clear smooth transparent rigid PVC film with the backing of Hard tempered printed Aluminium foil.

Pack Size(s): 8, 50 and 100 Tablets in a carton box. Not all pack sizes may be marketed.

Marketing Authorisation Holder and Manufacturer RIA Generics Limited

36 Ingleby Way,

Wallington,

SM6 9LR

United Kingdom

This leaflet was last revised in November 2025.

If you would like this leaflet in a different format or register a complaint, please contact the Marketing Authorisation holder listed above.