My 22-year-old daughter has regular night sweats that disrupt her sleep. She has taken fluoxetine for a long time and also has low iron levels, but other blood tests seem OK. What can she do to stop them?

Name and address supplied.

Dr Martin Scurr replies: Night sweats are a common side effect of fluoxetine, and other SSRIs (selective serotonin-reuptake inhibitors), a group of medicines used to treat depression and anxiety. These can affect the way the brain regulates temperature.

However, the drug may not be entirely to blame. Sweats can be made worse by anxiety, alcohol or hormonal variations during the menstrual cycle.

There is also the possibility of an undiagnosed health problem, especially if the night sweats started recently and are accompanied by other symptoms such as unexpected weight loss or fever. Possible causes include an overactive thyroid, a viral infection and tuberculosis. 

I’d expect the blood tests she has already had have included checks on thyroid function, as well as C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) – both are markers that rise when there’s inflammation in the body, for example from infection or injury. From your letter, it sounds as if these results were normal.

I don’t think the low iron levels are a factor in the night sweats. Nevertheless, I think your daughter should have a physical examination by her GP to rule out any underlying illness.

If nothing is found, fluoxetine seems the most likely explanation for the night sweats. Reducing the dose might help ease them.

I struggle with allergies and insect bites, especially in summer. I use insect repellent when I go outside, particularly in the garden, and always wear long sleeves and trousers. Even so, I still get bitten and feel itchy, and I take fexofenadine (an antihistamine) for this. Is there a natural preventative you can recommend?

Irene Day, by email.

Dr Martin Scurr replies: You’re far from alone with this problem, so other readers will no doubt be interested in the various options worth trying.

The only genuinely natural product I can recommend is oil of lemon eucalyptus – not to be confused with ordinary lemon eucalyptus essential oil, which is quite different.

Although both come from the same tree – the lemon eucalyptus, native to Australia – there are differences in the way they are processed.

Oil of lemon eucalyptus contains a compound called PMD (para-menthane-3,8-diol) that multiple studies have shown gives good protection against biting flies. In my view it’s your best natural option.

If you are open to something that is derived from a natural source rather than being fully natural itself, then picaridin is another good option.

It’s a synthetic insect repellent modelled on piperine, a compound found naturally in black pepper plants. So while it isn’t strictly natural, it is synthesised from a natural substance. It’s highly effective against mosquitoes, ticks, biting flies, chiggers (harvest mites) and gnats.

Whichever you choose, the key is to apply it carefully and consistently. Put it on when you’re indoors as well – insects often find their way through open windows in hot weather.

Fexofenadine will help if you do get bitten. Another option is a steroid cream, 1 per cent hydrocortisone (no need for a prescription), or Anthisan cream, which is anti-itch.

Proton pump inhibitors (PPIs) such as omeprazole are taken by millions to ease heartburn and acid reflux.

Now research suggests they may be linked to a flare-up of conditions such as chronic bronchitis and emphysema, making patients more vulnerable to potentially dangerous infections. It’s the latest in a mounting list of concerns about the long-term use of PPIs.

These drugs suppress the production of stomach acid and were hailed as a breakthrough when introduced in the late 1980s as they were much more effective than the H2-receptor antagonists that preceded them.

For years PPIs were considered safe, yet we overlooked the key role stomach acid plays in digesting protein, aiding iron, calcium and vitamin absorption and boosting our defences against bacteria and viruses – the latest study showed that PPIs effectively allowed disease-causing bacteria to travel up through the stomach and ultimately into the lungs.

It’s important to only use PPIs at the lowest effective dose and for the shortest time possible. They’re certainly not the panacea we once thought.