Patient info

Half Securon SR 120 mg tablets – patient leaflet, side effects, dosage

Updated:
Key facts
Status:
Prescription only (POM)
Medicine strength:
120 mg
Other strengths and forms:
Contains active substance:
ATC code:

Patient leaflet - Half Securon SR 120 mg tablets

1. WHAT HALF SECURON SR IS AND WHAT IS IT USED FOR

Half Securon SR contains the active substance verapamil hydrochloride.

Half Securon SR belongs to a group of medicines called calcium channel blockers. Calcium channel blockers change the amount of calcium getting into the muscle cells in your heart and blood vessels. This can change the strength and speed with which your heart beats. It also opens up the blood vessels so blood can be pumped around the body more easily. This helps more oxygen to get to your heart muscle and can lower your blood pressure.

Half Securon SR is used to treat hypertension (high blood pressure) and to prevent angina (chest pain) attacks. The tablets may also be prescribed following a heart attack, to prevent another attack occurring.

2. WHAT YOU NEED TO KNOW BEFORE YOU TAKE HALF SECURON SR

Do not take Half Securon SR:

  • If you are allergic to verapamil hydrochloride or any of the other ingredients of this medicine (listed in section 6).
  • If you have had a heart attack with shock.
  • If you had a heart attack, particularly if a slow heartbeat, low blood pressure or a type of heart failure called ‘left ventricular failure’.
  • If you have an abnormally slow or irregular heartbeat. If you have second- or third-degree atrioventricular block or sino-atrial block. This is a disorder where parts of your heart may beat at the wrong time causing it not to pump blood around the body very well (unless a permanent pacemaker is in place).
  • If you have a problem where your heart beats very slowly (bradycardia), unless you have been fitted with a pacemaker.
  • Do you have or have you ever suffered from heart problems such as heart failure or the heart condition called Wolff-Parkinson-White?
  • If you are currently being treated with ivabradine (for heart conditions)?

Warnings and Precautions

Talk to your doctor or pharmacist before using Half Securon SR

  • If you are pregnant or planning to become pregnant, or you are breast feeding.
  • If you have liver or kidney problems.
  • If you have very low blood pressure.
  • If you are currently receiving lipid lowering agents (e.g., simvastatin, atorvastatin or lovastatin)
  • If you have a condition where the nerve to muscle transmission is affected e.g. myasthemia gravis, Lambert-Eaton syndrome, advanced Duchenne muscular dystrophy.

Take special care with Half Securon SR

Tell your surgeon or dentist that you are taking Half Securon SR if surgery is planned as it may affect the anaesthetic used.

Other medicines and Half Securon SR Tell your doctor or pharmacist if you are taking any medicines with or without a prescription or have recently taken any of the following medicines:

  • beta-blockers such as atenolol, propranolol and metoprolol (used to treat high blood pressure and heart conditions)
  • alpha blockers such as prazosin and terazosin (used to treat high blood pressure and heart conditions)
  • diuretics (also called ‘water pills’)
  • medicines known as "statins" such as atorvastatin, lovastatin, simvastatin (used to lower cholesterol levels)
  • quinidine, flecainide, disopyramide, digoxin and digitoxin (used to treat high blood pressure or an abnormal heart beat (arrhythmia))
  • Dabigatran (used to thin blood) and direct oral anticoagulants (DOACs)
  • Ivabradine (used to treat certain heart diseases)
  • medicines used to treat depression, anxiety or psychosis. These include the herbal product St John’s Wort or imipramine, buspirone and lithium
  • medicines known as immunosuppressants such as cyclosporine, sirolimus, everolimus and tacrolimus (used to prevent organ transplant rejection)
  • glyburide (glibenclamide), medicine used to treat certain types of diabetes
  • aspirin (a non-steroidal anti-inflammatory painkiller (NSAID) used to relieve pain and reduce fever)
  • almotriptan (used to treat migraine)
  • midazolam ( used as a sedative or anaesthetic)
  • theophylline (used to treat asthma)
  • doxorubicin (an anti-cancer medicine)
  • cimetidine (used to treat indigestion or stomach ulcers)
  • rifampicin (used to treat tuberculosis and other types of infection)
  • carbamazepine, phenytoin or phenobarbital (phenobarbitone), medicines used as anti-convulsants
  • ritonavir (used to treat HIV)
  • erythromycin, clarithromycin and telithromycin (used to treat types of infection)
  • colchicine or sulfinpyrazone (used to treat gout)
  • metformin. Verapamil may decrease the glucose-lowering effect of metformin.
  • antihypertensives (used to treat hypertension)
  • vasodilators (open (dilate) blood vessels)

Half Securon SR with drink and alcohol

  • Do NOT drink grapefruit juice whilst taking Half Securon SR as it can affect the absorption of this medicine. This does not occur with other fruit juices such as orange, apple or tomato juice.
  • Half Securon SR will increase the time your body takes to get rid of alcohol. This means that you may not have to drink as much for your blood alcohol levels to be above the legal limit to drive. It will also take you longer to sober up.

Pregnancy, breast-feeding and fertility

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

Sodium

Half Securon SR: This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.

Driving and using machines

Do NOT drive, operate machinery or do anything that requires you to be alert, until you know how the tablets affect you.

Half Securon SR can make some people feel dizzy, especially when they first start to take the tablets.

3. HOW TO TAKE HALF SECURON SR

ALWAYS take this medicine exactly as your doctor has told you. Check with your doctor if you are not sure.

TAKE YOUR TABLETS with a glass of water. You should swallow the tablets without chewing or crushing them. It does not matter if you have not eaten.

The number of tablets that you will need to take will depend on what you are being treated for:

ADULTS:

Hypertension (high blood pressure)

The recommended dose is one Securon SR 240 mg tablet a day. If you have not taken Securon SR 240 mg before, your doctor may prescribe a lower dose such as a Half Securon SR 120 mg tablet each day. The maximum dose to treat high blood pressure is 480 mg each day. This is usually taken as one Securon 240 mg tablet in the morning and one in the evening, leaving a gap of about 12 hours between each dose.

2705

26.09.25[15]

Angina (chest pain)

The usual starting dose for angina is one Securon SR 240 mg tablet taken twice a day. You should take one tablet in the morning and one in the evening, with a gap of about 12 hours in between them. Your doctor may prescribe a lower dose according to your symptoms.

Following a heart attack

The usual dose following a heart attack is 360 mg each day. This may be taken as one Securon SR 240 mg tablet in the morning and a Half Securon SR 120 mg tablet in the evening or as one Half Securon SR 120 mg tablet taken three times a day. The doctor will usually wait at least a week after your heart attack before prescribing these tablets.

CHILDREN:

Half Securon SR is NOT recommended for children under 12 years of age.

Elderly

The dose will be the same as that for adults. If you have kidney or liver problem, your doctor may lower your dose.

If you take more Half Securon SR than you should

If you take more tablets than prescribed (an overdose) you should contact a doctor or go to the nearest hospital casualty department IMMEDIATELY taking your tablets with you.

If you forget to take Half Securon SR

If you forget to take your tablets take them as soon as you remember, unless it is almost time for your next dose. If it is, do not take the missed dose at all. Do not take double dose to make up for a forgotten tablet.

If you stop taking Half Securon SR

If you stop taking your tablets your condition may get worse. It is important that you keep taking these tablets until your doctor tells you to stop. Do NOT stop just because you feel better.

Other things to remember about Half Securon SR

  • The tablets should NOT be crushed, chewed or sucked, as this will affect the modified-release formulation of the product.

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

4. POSSIBLE SIDE EFFECTS

As with all medicines, Half Securon SR can cause side effects, although not everyone will suffer from them. If you experience any other unusual symptoms whilst taking your tablets, tell your doctor or pharmacist.

Tell your doctor IMMEDIATELY if you experience any of the following side effects:

  • Yellowing of the skin or eyes, a fever or tenderness around the middle. These are signs that your liver may not be functioning as well as usual
  • Palpitations, chest pains for the first time or chest pains becoming more frequent, swollen ankles, hot and painful hands or feet
  • Swelling of the limbs
  • Unexpected wheezing, difficulty breathing, swelling of the mouth, lips or tongue or severe skin rash

The most common side effect is constipation. Other side effects include abnormal heart beat, flushing of the face or neck, headaches, feeling or being sick, abdominal pain or discomfort, dizziness, vertigo, tinnitus (ringing or buzzing in the ears), tiredness, tremor, movement disorders, muscle weakness, aches and pains in the joints and/or muscles, skin rash or itching, a tingling or prickling feeling on the skin, numbness and hair loss. Impotence may occur rarely.

Other side effects might occur if Half Securon SR is used for a long time. Tell your doctor if you develop swollen gums which start to spread over your teeth, or if your breasts swell (males) or start to produce milk (males and females). These effects are rare and are resolved upon stopping taking the tablets.

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 HALF SECURON SR

Keep out of the sight and reach of children.

Do not store above 25°C. Store in the original package.

Do not take your tablets after the expiry date shown on the carton.

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

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 protect the environment.

6. CONTENTS OF THE PACK AND OTHER INFORMATION

The active ingredient in Half Securon SR tablets is verapamil hydrochloride. Each tablet contains 120 mg of verapamil hydrochloride in a modified release formulation.

The inactive ingredients are microcrystalline cellulose, sodium alginate, povidone, magnesium stearate, purified water, hypromellose, macrogol 400, macrogol 6000, talc, titanium dioxide (E171) and Montan Glycol Wax.

What Half Securon SR Tablets look like:

Half Securon SR are round, white tablets marked 'KNOLL' on one side and '120 SR' on the other.

Half Securon SR tablets are available in blister packs of 28 and 98 tablets calendar blister strips.

MANUFACTURER AND PRODUCT LICENCE HOLDER

Manufactured by

Famar A.V.E., Anthoussa Avenue 7, Anthoussa Attiki 15349, Greece.

Procured from within the EU by Product Licence holder:

Star Pharmaceuticals Ltd, 5 Sandridge Close, Harrow, HA1 1XD. Repackaged by Servipharm Ltd.

Leaflet revision and issue date (Ref) 26.09.25[15]

Half Securon is a trademark of Mylan Healthcare GmbH.

Blind or partially sighted?

Is this leaflet hard to see or read?

Call 020 8423 2111 to obtain the leaflet in a format suitable for you.

POM

Half Securon SR 120mg Tablets - PL 20636/2705

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PLPI 20636/2705

Last revision stated in the text: 26 September 2025 · MHRA data as of 13 October 2026

Found a mistake? Tell us on the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Facts about Half Securon SR 120 mg tablets

Prescription needed? Yes, prescription-only medicine (POM)
Active substance Verapamil
Strength 120 mg
Pharmaceutical form Modified-release tablet
How is it taken Oral
Is it available? Listed as available (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Drug group (ATC)
  1. C Cardiovascular system drugs
    1. C08 Calcium channel blockers
      1. C08D Selective calcium channel blockers with direct cardiac effects
        1. C08DA Phenylalkylamine derivatives, selective calcium channel blockers with direct cardiac effects
          1. C08DA01 verapamil
Marketing authorisation PLPI 20636/2705
Codes BNF 02060200

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 10.2.0 of 19 October 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.