Summer ailments: interactions with medication

 In Medications, Pharmacy Information

With summer in full swing and the various ailments it brings with it, there are a few additional factors that need to be kept in mind when prescribing for patients.

Hay fever

Hay fever affects about 25% of the population in the UK, and often requires medication to keep it under control. Be aware that antihistamines are often used: these can cause drowsiness (especially the older ones such as chlorphenamine and promethazine) and could have an additive effect with other medications’ a person is taking.


Sufferers of respiratory disorders such as asthma and COPD can often find their condition gets worse in the summer months, due either to the effects of hay fever or increased humidity. Be aware that patients with these diseases may need to have their inhaler therapy reviewed.


It is important that high-factor sun cream is used in the summer months to protect the skin and to help prevent premature aging. This is especially important for patients on certain medications (such as chlorpromazine and some antibiotics) as this can cause photosensitivity, which means they will get a very severe rash when they go out in the sun.

Vitamin D deficiency

Exposure to sun causes people to naturally synthesise vitamin D, which can mean that some people do not require supplementation. However, people with dark skin and those who do not spend much time outside will still require a vitamin D supplement in the summer months.


It is important for everyone to stay hydrated in the summer months, but this is particularly important for patients taking lithium. Dehydration concentrates the amount of lithium in the blood and leads to a higher plasma level with an increased risk of side effects.

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