Medicines applied to the skin are often assumed to be safer than tablets because they act where you put them. That is broadly true, and it is not the whole story: some of what you apply is absorbed into the bloodstream, and how much depends on factors you control.
Absorption increases with a larger treated area, a longer period of use, broken or inflamed skin, thin skin such as the face, eyelids and genitals, skin folds where surfaces touch, and covering the area with a dressing or tight clothing.
Applied thinly to a small patch of intact skin for a few days, most topical medicines stay largely local. Applied liberally over a wide area for weeks under occlusion, the picture changes.
Common side effects of this pharmacy medicine or category
- Redness, stinging, burning or itching where applied
- Dryness or peeling
- A rash that can look like the condition being treated
- Increased sensitivity to sunlight with some products
- Skin thinning with prolonged steroid use
A rash that appears or worsens where you applied something is worth thinking about rather than treating harder. It may be irritation from the product, or an allergy to it, including to a preservative or fragrance rather than the active ingredient. Applying more of the same is a common and unhelpful response. See creams causing a rash.
Interactions and duplicate-ingredient risks
Topical medicines count towards your total of that medicine. An anti-inflammatory gel plus anti-inflammatory tablets means two NSAIDs. A steroid cream on a large area plus steroid tablets adds up. See NSAID side effects.
Do not apply several products to the same area without checking, and wash your hands after applying unless treating them.
Children, pregnancy, older adults and chronic medicine cautions
- Children. Absorb proportionally more than adults because of a larger skin area relative to body size, and their skin is thinner. Use only what has been advised for their age.
- Pregnancy and breastfeeding. Ask before using anything on a large area. If breastfeeding, avoid applying to the breast where a baby feeds.
- Older adults, whose thinner skin absorbs more and is more easily damaged.
- Broken, weeping or infected skin, where absorption rises sharply and some products are unsuitable.
Warning signs and overdose concerns
Get emergency help for difficulty breathing, or swelling of the face, lips or throat.
Stop and seek advice for a spreading or blistering rash, skin that becomes very sore or breaks down, signs of infection such as increasing pain with warmth, swelling or pus, or symptoms elsewhere in the body after using a product widely.
Also see someone if the condition has not improved in the time the label allows, since applying something indefinitely to an undiagnosed problem delays finding out what it is.
Questions to ask a pharmacist before using it
- How much should I use, how often, and for how long?
- Is it safe to use on my face, or in skin folds?
- Should I cover the area or leave it open?
- Does it count towards anything else I take?
- What should I do if the rash gets worse?
Related OTC and medicine-safety guides
- Topical medicine side effects
- Skin medicine side effects
- OTC medicine side effects
- When to see a doctor about an OTC medicine
- Report an OTC medicine side effect
See also steroid cream side effects and pain relief gel side effects.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.