My dog only itches at certain times of year. Is that still an allergy?

Very likely. Environmental allergies to pollen are often seasonal, flaring in spring, summer or autumn. Keeping a simple diary of itchy periods helps your vet spot the pattern.

Can I give my dog an over-the-counter antihistamine?

Only with your vet's guidance. Doses differ from human doses, antihistamines help only some dogs, and some products contain added decongestants that are toxic to dogs.

Is there a test for food allergies in dogs?

Blood, saliva and hair tests aren't reliable for diagnosing food allergies. A strict elimination diet for 8 to 12 weeks, followed by reintroducing the old food, is the most reliable method.

Can I catch my dog's skin condition?

Most allergies and yeast infections aren't contagious. Sarcoptic mange is the exception: it spreads between dogs and can cause temporary itchy bumps on people, so tell your vet if anyone in the house is itchy too.

Itchy Dog? 8 Common Skin Allergies and Look-Alike Problems

This article is general information, not veterinary advice. If your pet seems unwell or you are worried, call your vet.

Every dog scratches now and then. But when scratching, licking, chewing and rubbing start disrupting sleep, or you notice red skin, hair loss or a funky smell, something is going on. Allergies are one of the most common reasons dogs visit the vet, and they often open the door to secondary skin infections that look similar and need their own treatment.

Here are the usual suspects, what they tend to look like, and what you can do while you work with your vet.

The allergies

1. Flea allergy dermatitis

What it is: An allergic reaction to flea saliva. For a sensitive dog, a few bites can set off days of intense itching.

What you’ll see: Itching and scabs concentrated over the lower back, base of the tail, rump and back of the thighs. You may never find a flea, because allergic dogs often groom them away.

What helps: Year-round, vet-recommended flea prevention for every dog and cat in the home, not just the itchy one. Wash bedding hot and vacuum often, since flea eggs and larvae live in the environment.

2. Environmental allergies (atopic dermatitis)

What it is: An allergic reaction to things in the environment such as pollen, mold spores and house dust mites, similar to hay fever in people. It usually starts in young adult dogs.

What you’ll see: Paw licking and chewing, face rubbing, itchy armpits, belly and groin, and recurring ear infections. Signs may be seasonal or year-round, depending on the trigger.

What helps: Wiping paws and belly after walks, regular bathing with a vet-recommended shampoo, and washing bedding. Atopic dermatitis is lifelong but manageable, and modern prescription anti-itch medications and allergy immunotherapy work well for many dogs.

3. Food allergy

What it is: An immune reaction to a protein in the diet. Common culprits include beef, dairy, chicken and wheat, usually after the dog has eaten them for a long time.

What you’ll see: Year-round itching, often of the ears, paws and rear end, recurring ear infections, and sometimes soft stools or more frequent bowel movements.

What helps: A strict elimination diet using a prescription hydrolyzed food or a novel protein your dog has never eaten, for 8 to 12 weeks. No treats, chews, table scraps or flavored medications during the trial unless your vet approves them. If itching improves and returns when the old food is reintroduced, you have your answer.

4. Contact dermatitis

What it is: A reaction to something the skin touches, such as certain plants, cleaning products, carpet fresheners or shampoos. It’s less common than the allergies above.

What you’ll see: Redness and itching on thinly furred areas that touch the ground: belly, groin, armpits, chin and between the toes.

What helps: Rinsing after outdoor play and switching to fragrance-free detergents and cleaners. Change one product at a time so you know what made the difference.

The look-alikes (often caused by allergies)

5. Yeast overgrowth (Malassezia)

What it is: Yeast that normally lives on the skin multiplies when skin is inflamed, greasy or damp.

What you’ll see: A musty smell, greasy or flaky skin, redness, darkened or thickened skin over time, and itchy ears with brown waxy discharge.

What helps: Your vet can confirm yeast with a quick skin or ear sample and prescribe medicated shampoo, wipes or ear treatment. Dry your dog thoroughly after baths and swims. Long term, controlling the underlying allergy prevents repeat flares.

6. Bacterial skin infection (pyoderma)

What it is: A bacterial infection, usually secondary to scratching or allergies.

What you’ll see: Pimple-like bumps, crusts, circular scaly rings, patchy hair loss and sometimes a smell.

What helps: A vet visit. Treatment may include medicated shampoos, sprays or antibiotics. Finish the full course even if the skin looks better.

7. Mites (mange)

What it is: Not an allergy, but a parasite that can mimic one. Sarcoptic mange is intensely itchy and contagious to other dogs. Demodectic mange is caused by mites that normally live on all dogs; it’s usually not itchy at first and is most common in puppies.

What you’ll see: Sudden, severe itching, often starting on the ear flaps, elbows and belly (sarcoptic), or patchy hair loss around the face and legs (demodectic).

What helps: Your vet will take skin scrapings. Several modern prescription parasite treatments are effective. Wash bedding and keep an itchy dog away from other dogs until your vet says otherwise.

8. Hot spots (acute moist dermatitis)

What it is: A painful, rapidly spreading patch of inflamed skin, triggered when a dog licks or scratches an itchy spot repeatedly.

What you’ll see: A red, wet, oozing patch, often with matted fur, commonly on the neck, cheeks, hips or thighs. Hot spots can grow noticeably within hours.

What helps: A vet visit to clip, clean and treat the area, plus a cone or other barrier to stop licking. Then find the trigger, which is often fleas or an allergy.

Your at-home checklist

Score the itch. Rate it from 0 to 10 each evening for two weeks and note where your dog scratches.
Note the pattern. Seasonal or year-round? Better or worse after walks, baths or a food change?
Check parasite prevention. Are all pets up to date?
Rinse and dry. Wipe paws and belly after walks, and dry thoroughly after baths and swims.
Go fragrance-free with laundry and cleaning products.
Take photos of affected skin so your vet can see how it changes.

Don’t try human creams, essential oils or home remedies on broken skin without asking your vet. Some are toxic if licked, and many make irritated skin worse.

When to call the vet

Book an appointment if itching hasn’t improved within a week or two, or sooner if it’s getting worse. See your vet promptly if your dog has:

Open sores, oozing patches or a hot spot
Head shaking, ear odor, discharge or a painful ear
Itching severe enough to disrupt sleep or eating
Spreading patches of hair loss, or people in the home who are itchy too

Seek emergency care for facial swelling, hives across the body, vomiting, collapse or trouble breathing, which can signal a serious allergic reaction.