Medicines in pregnancy: what is safe, what to avoid and when to ask
The moment you find out you are pregnant, the way you think about medicines changes. Suddenly every packet you pick up feels like a risk. Many people avoid taking anything at all — including treatments that would genuinely help them — out of fear that any medicine could harm their baby. That instinct is understandable, but the picture is more nuanced than that.
This article gives you clear, NHS-accurate guidance on what is generally considered safe, what to avoid, and when to ask someone who can give you advice tailored to your specific situation. It is guidance, not a prescription. Your midwife, GP or pharmacist is always the right person to speak to if you have any doubt.
The question most people get wrong
It is tempting to assume that taking no medicine is always the safest choice in pregnancy. In some situations that is right. In many, it is not.
Untreated pain, fever, infections and ongoing health conditions can all pose risks to you and your baby. A high fever in early pregnancy, for example, has been associated with neural tube defects. Untreated urinary tract infections can progress to kidney infections, which carry real risks in pregnancy. Poorly controlled asthma reduces the oxygen supply to your baby.
The general principle from the NHS and clinical pharmacologists is this: the risk of not treating an illness often outweighs the risk of a well-chosen medicine taken at the right dose. If you are unwell and unsure what to do, speak to your pharmacist, midwife or GP. They can help you weigh up the options for your situation.
Medicines that are generally considered safe
The following are broadly recognised as acceptable options during pregnancy when used at the recommended dose. Always read the packet and ask your pharmacist if you are unsure whether a specific product or dose is right for you.
Paracetamol
Paracetamol is the recommended first-choice painkiller and fever reducer throughout pregnancy. It is the medicine the NHS and MHRA point to when pregnant people need pain relief.
The key is to use it at the lowest dose that works, for the shortest time needed. Occasional use at the standard recommended dose (1g, up to four times a day for adults) is considered safe. In 2023, the MHRA updated its guidance to note that long-term or regular use of paracetamol in pregnancy is being studied more closely, and to reinforce the message about using the minimum effective dose. However, occasional use at recommended doses remains the NHS recommendation, and it is not a reason to avoid paracetamol when you genuinely need it.
Do not take paracetamol combined with other medicines (such as cold and flu remedies) without checking the label, as many of these already contain paracetamol, which could push you over the safe daily limit.
Antacids and heartburn remedies
Heartburn and indigestion are extremely common in pregnancy, particularly in the second and third trimesters. Most antacids are considered safe to use. Products such as Gaviscon and standard calcium carbonate antacids are widely used in pregnancy and are not expected to cause harm at normal doses.
One thing to watch: avoid antacids that are very high in sodium (salt) if you are monitoring your salt intake or if your midwife has flagged any concerns about fluid retention or blood pressure. Check the label, or ask your pharmacist to recommend a suitable product.
If heartburn is severe or persistent, speak to your GP, as they can prescribe treatments that are also considered appropriate in pregnancy.
Antihistamines
If you need an antihistamine for allergies, hay fever or itching, chlorphenamine (sold as Piriton) is the antihistamine most often recommended during pregnancy because it has a longer history of use and more available safety data. It can cause drowsiness, which may actually be helpful at night but is worth bearing in mind during the day.
Non-drowsy antihistamines such as loratadine and cetirizine are also considered by many clinicians to be reasonable options in pregnancy, though the safety data is more limited than for chlorphenamine. Neither has been shown to cause harm, but the evidence base is smaller.
Check with your pharmacist before choosing, and check the packet carefully, as some antihistamine-containing products also include decongestants, which are best avoided (see below).
Clotrimazole for thrush
Thrush is common in pregnancy because hormonal changes affect the vaginal environment. Clotrimazole cream or pessary (sold as Canesten and other brands) used topically is considered safe in pregnancy.
One important point: use the cream or pessary by hand rather than with the applicator when you are pregnant. And do not use oral fluconazole tablets (the single-dose capsule sometimes used for thrush) in pregnancy. Some studies have found an association between oral fluconazole and an increased risk of miscarriage, and the MHRA advises against its use in pregnancy. The topical treatment is effective for most cases and does not carry the same concern.
Iron supplements
Iron deficiency anaemia is common in pregnancy as your body produces more blood and your iron demands increase. If your blood tests show low iron or anaemia, your GP or midwife will often prescribe iron supplements. These are appropriate and important to take as directed.
Some people find iron supplements cause constipation or an upset stomach. Taking them with a small amount of food (rather than on an empty stomach) can help, though food can slightly reduce absorption. If side effects are a problem, speak to your midwife, as different formulations are sometimes better tolerated.
Folic acid
Folic acid is strongly recommended before conception and during at least the first 12 weeks of pregnancy to reduce the risk of neural tube defects such as spina bifida. The standard recommended dose is 400 micrograms (mcg) daily.
If you have a higher risk of having a baby with a neural tube defect (for example, if you have epilepsy, diabetes, a BMI over 30, or a family history), your GP will usually prescribe 5mg folic acid daily. Take the dose your GP or midwife recommends for your situation.
Vitamin D
The NHS recommends that pregnant and breastfeeding people take a daily supplement containing 10 micrograms (400 IU) of vitamin D throughout pregnancy. This is available as a pregnancy supplement or as a standalone supplement. Avoid very high-dose vitamin D supplements unless prescribed, as very large doses are not beneficial and could potentially cause harm.
Medicines to avoid in pregnancy
The following medicines carry known risks or have insufficient safety data in pregnancy, and are generally recommended to be avoided. This is not an exhaustive list. If a medicine is not on this list, that does not mean it is safe — it means it has not been mentioned here. When in doubt, ask.
Ibuprofen and other NSAIDs
Ibuprofen, naproxen, diclofenac and other non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided in pregnancy, particularly from 20 weeks onwards. The most serious concern is premature closure of the ductus arteriosus, a blood vessel that plays an important role in the baby's circulation before birth. NSAIDs taken after 20 weeks have also been associated with reduced amniotic fluid (oligohydramnios). The NHS recommends avoiding ibuprofen throughout pregnancy.
If you are in pain, use paracetamol instead. If paracetamol is not enough, speak to your GP about what is appropriate for your situation.
Aspirin at standard pain-relief doses
Standard-dose aspirin (for pain relief) is not recommended in pregnancy. However, it is important to know that low-dose aspirin (75 to 150mg daily) is actually prescribed in pregnancy for specific medical reasons, particularly to reduce the risk of pre-eclampsia in people with certain risk factors. This is a deliberate, supervised clinical decision, not the same as taking aspirin for a headache. Do not take aspirin for pain relief in pregnancy, but if your GP or midwife has prescribed low-dose aspirin for a specific reason, continue to take it as directed.
Codeine and codeine-containing products
Codeine is an opioid painkiller. It is found in some over-the-counter products such as co-codamol, Nurofen Plus (also contains ibuprofen, so also to be avoided) and some cough medicines. Codeine should be avoided in pregnancy if possible. If there is a genuine clinical need and it is used for a very short period under medical guidance, the risks are lower, but it is not something to take without discussing with your GP first. The main concern in late pregnancy is neonatal opioid withdrawal syndrome in the newborn if codeine is used regularly near term.
Oral retinoids (isotretinoin / Roaccutane and related medicines)
This is the clearest and most serious category on this list. Isotretinoin (sold as Roaccutane and other brand names) and other oral retinoids used for acne are severely teratogenic — meaning they cause major birth defects with near certainty if taken during pregnancy. These medicines must not be taken during pregnancy under any circumstances.
Because the risk is so high, isotretinoin in the UK is only prescribed as part of a formal pregnancy prevention programme that requires effective contraception before, during and after treatment. If you are on isotretinoin and think you may be pregnant, seek medical advice urgently.
Tetracycline antibiotics
Antibiotics such as tetracycline, doxycycline and minocycline should be avoided in pregnancy. They are taken up by developing bones and teeth and can cause permanent discolouration of the baby's teeth and affect bone development. Other antibiotic classes (for example, some penicillins and cephalosporins) are considered safer and are routinely prescribed in pregnancy when needed. If you need an antibiotic in pregnancy, your GP will prescribe an appropriate one.
Decongestants containing pseudoephedrine or phenylephrine
Many over-the-counter cold and flu remedies, sinus tablets and nasal sprays contain decongestants such as pseudoephedrine or phenylephrine. These are generally avoided in pregnancy, particularly in the first trimester, because they can cause constriction of blood vessels including those supplying the placenta. Some cold and flu products also contain other medicines (such as ibuprofen or aspirin) that are also to be avoided.
For a blocked nose or congestion, a plain saline nasal spray or steam inhalation is a safe alternative. If symptoms are severe, speak to your pharmacist or GP.
Herbal remedies and "natural" supplements
This is an area where a lot of misinformation circulates. "Natural" does not mean safe in pregnancy. Most herbal remedies have not been tested for safety in pregnancy at all, so the risks are simply unknown.
Some specific concerns:
- Raspberry leaf: marketed to help prepare for labour, but it is thought to stimulate uterine contractions. It is sometimes used by some midwives only in the very late third trimester and only with guidance. It should not be used earlier in pregnancy.
- Evening primrose oil: similarly thought to affect uterine tissue; avoid unless specifically guided by your midwife.
- High-dose vitamin A: large doses of vitamin A (above 700mcg daily from supplements) can cause birth defects. Liver and liver products are also very high in vitamin A and are recommended to be avoided in pregnancy for this reason. Normal dietary intake of vitamin A from vegetables is not a concern.
- St John's Wort: can interact with other medicines and has insufficient safety data in pregnancy.
- Herbal teas in large quantities: some herbal teas are not recommended in pregnancy, including those containing liquorice root, chamomile in large amounts, or other herbs. Plain ginger tea (in moderate amounts) is generally considered fine and may help with nausea.
Stick to the supplements recommended specifically for pregnancy (folic acid, vitamin D, iron if prescribed) and ask your midwife before adding anything else.
Prescription medicines: please do not stop without asking
If you take a medicine every day for an ongoing condition, finding out you are pregnant may make you wonder whether to keep taking it. The answer is almost always: do not stop without speaking to your doctor first.
Many conditions require continuous treatment in pregnancy, including:
- Epilepsy: seizures during pregnancy carry serious risks for both you and your baby. Your neurologist and obstetrician will work together to find the safest regimen for you — but stopping anti-epileptic medicine suddenly is dangerous.
- Thyroid conditions: both hypothyroidism and hyperthyroidism require careful management in pregnancy. Untreated thyroid disorders are associated with miscarriage, preterm birth and developmental effects on the baby.
- Asthma: poorly controlled asthma reduces oxygen to the baby. Most inhalers used for asthma are considered safe in pregnancy and should be continued.
- Mental health conditions: depression and anxiety in pregnancy are common and are associated with poor outcomes if untreated. Many antidepressants are considered acceptable in pregnancy, and the risk of stopping is often greater than the risk of continuing. Your GP or psychiatrist can advise on the safest option.
- High blood pressure: some blood pressure medicines are safe in pregnancy and others need to be swapped for alternatives. Your GP will review your treatment when you become pregnant.
The bottom line: book an appointment with your GP as soon as you find out you are pregnant so that any ongoing prescriptions can be reviewed. Do not make changes on your own.
What to do when you are unsure
You do not always need to book a GP appointment to get advice. These are your best options:
- Your pharmacist: pharmacists are highly trained in medicines safety and can advise you on specific products, including which formulation to choose and what to avoid. This is a free service and you do not need an appointment. For most over-the-counter questions, your pharmacist is the fastest and most convenient route.
- Your midwife: your community midwife is a good source of advice, particularly for questions about your ongoing pregnancy care or if you have a condition that is being managed during pregnancy.
- BUMPS (Best Use of Medicines in Pregnancy): bumps-drugsinpregnancy.org is a reliable, evidence-based resource produced for healthcare professionals and parents that gives specific information on individual medicines in pregnancy. It is well worth bookmarking.
- NHS 111: if you have already taken something and you are worried about it, call 111. They can provide reassurance or triage you to the right service. Do not sit and worry — call.
- Your GP: for anything that involves a change to a prescription, an ongoing condition, or symptoms that need diagnosis, see your GP.
A quick reference summary
| Medicine | Status in pregnancy |
|---|---|
| Paracetamol | Generally safe — lowest effective dose, shortest time |
| Ibuprofen and other NSAIDs | Avoid throughout pregnancy |
| Aspirin (pain-relief dose) | Avoid — low-dose aspirin 75-150mg for medical reasons only under supervision |
| Codeine | Avoid where possible; medical supervision only if essential |
| Most antacids (e.g. Gaviscon) | Generally safe — check sodium content; ask pharmacist |
| Chlorphenamine (Piriton) | Generally considered acceptable; first-choice antihistamine |
| Loratadine, cetirizine | Often used; less data than chlorphenamine; check with pharmacist |
| Clotrimazole cream/pessary (Canesten) | Safe topically for thrush |
| Oral fluconazole (Diflucan) | Avoid in pregnancy |
| Isotretinoin / Roaccutane | Do not take — severe teratogen |
| Tetracycline antibiotics | Avoid — affects baby's developing teeth and bones |
| Decongestants (pseudoephedrine, phenylephrine) | Avoid — use saline nasal spray instead |
| Iron supplements | Recommended if prescribed for anaemia |
| Folic acid 400mcg (or 5mg if higher risk) | Strongly recommended, especially first 12 weeks |
| Vitamin D 10mcg | Recommended throughout pregnancy |
| Herbal remedies (most) | Avoid — no safety data; "natural" does not mean safe |
Log your pregnancy symptoms and what helps
Cubby lets you track how you are feeling week by week and note what you are taking, so you have a clear picture for your midwife appointments.
Start freeFrequently asked questions
Can I take paracetamol in pregnancy?
Yes. Paracetamol is the recommended first-choice painkiller throughout pregnancy. Use the lowest dose that relieves your symptoms, for the shortest time. Occasional use at the standard adult dose (up to 1g, four times a day) is considered safe by the NHS. Avoid taking it regularly over long periods without discussing this with your midwife or GP.
Why can I not take ibuprofen in pregnancy?
Ibuprofen is an NSAID. NSAIDs can cause premature closure of the ductus arteriosus (a blood vessel in the baby's heart) and can reduce amniotic fluid levels, particularly after 20 weeks of pregnancy. The NHS advises avoiding ibuprofen throughout pregnancy. Use paracetamol instead. If paracetamol is not enough, speak to your GP.
Are antihistamines safe in pregnancy?
Chlorphenamine (Piriton) is the antihistamine most commonly used in pregnancy and has the most safety data. Loratadine and cetirizine are also used by many clinicians in pregnancy, but have a slightly smaller evidence base. Check with your pharmacist before choosing, and always check the product for any additional ingredients.
Is Canesten safe in pregnancy?
Clotrimazole cream or pessary (Canesten) used topically is considered safe in pregnancy. Insert the pessary by hand rather than using the applicator. Oral fluconazole tablets are not recommended in pregnancy.
Should I stop my prescribed medicine when I get pregnant?
No. Do not stop a prescribed medicine without speaking to your doctor or midwife first. Many conditions including epilepsy, thyroid disorders, asthma, mental health conditions and high blood pressure require continued treatment in pregnancy. Stopping suddenly can be more harmful than continuing. Book a review with your GP early in your pregnancy.
Are herbal medicines and supplements safe in pregnancy?
Most herbal remedies have not been tested for safety in pregnancy, so their risks are unknown. Natural does not mean safe. Raspberry leaf and evening primrose oil can stimulate uterine contractions. High-dose vitamin A supplements can harm the baby. Stick to folic acid, vitamin D and anything specifically recommended by your midwife or GP.